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Article

Multi-Morbidity and Risk of Breast Cancer among Women in the UK Biobank Cohort

by
Afi Mawulawoe Sylvie Henyoh
1,*,
Rodrigue S. Allodji
1,
Florent de Vathaire
1,
Marie-Christine Boutron-Ruault
2,
Neige M. Y. Journy
1 and
Thi-Van-Trinh Tran
1,*
1
Radiation Epidemiology Group, Center for Research in Epidemiology and Population Health, INSERM U1018, Paris Sud-Paris Saclay University, Gustave Roussy, 94800 Villejuif, France
2
Health across Generations Team, Center for Research in Epidemiology and Population Health, INSERM U1018, Paris Sud-Paris Saclay University, Gustave Roussy, 94800 Villejuif, France
*
Authors to whom correspondence should be addressed.
Cancers 2023, 15(4), 1165; https://doi.org/10.3390/cancers15041165
Submission received: 30 December 2022 / Revised: 7 February 2023 / Accepted: 8 February 2023 / Published: 11 February 2023
(This article belongs to the Special Issue Breast Cancer: Risk Factors, Prevention and Early Detection)

Abstract

:

Simple Summary

(Multi-)Morbidity shares common biological mechanisms or risk factors with breast cancer. However, the risk of breast cancer among women with (multi-)morbidity remains unclear. In this study, using data of 239,436 female participants aged 40–69 of the UK Biobank cohort, we identified five chronic disease patterns: no-predominant morbidity, psychiatric morbidities, respiratory/immunological morbidities, cardiovascular/metabolic morbidities, and unspecific morbidities. After a median follow-up of 7 years, 5326 women developed breast cancer. We found no association between breast cancer risk and either the number of chronic diseases or chronic disease patterns, apart from an increased risk among women aged younger than 50 with a psychiatric pattern. Women with any multi-morbidity were more likely to die or to be diagnosed with other cancers. Our findings suggest that multi-morbidity may not be a key factor to help identify patients at an increased risk of breast cancer.

Abstract

(Multi-)Morbidity shares common biological mechanisms or risk factors with breast cancer. This study aimed to investigate the association between the number of morbidities and patterns of morbidity and the risk of female breast cancer. Among 239,436 women (40–69 years) enrolled in the UK Biobank cohort who had no cancer history at baseline, we identified 35 self-reported chronic diseases at baseline. We assigned individuals into morbidity patterns using agglomerative hierarchical clustering analysis. We fitted Cox models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for breast cancer risk. In total, 58.4% of women had at least one morbidity, and the prevalence of multi-morbidity was 25.8%. During a median 7-year follow-up, there was no association between breast cancer risk (5326 cases) and either the number of morbidities or the identified clinically relevant morbidity patterns: no-predominant morbidity (reference), psychiatric morbidities (HR = 1.04, 95%CI 0.94–1.16), respiratory/immunological morbidities (HR = 0.98, 95%CI 0.90–1.07), cardiovascular/metabolic morbidities (HR = 0.93, 95%CI 0.81–1.06), and unspecific morbidities (HR = 0.98, 95%CI 0.89–1.07), overall. Among women younger than 50 years of age only, however, there was a significant association with psychiatric morbidity patterns compared to the no-predominant morbidity pattern (HR = 1.25, 95%CI 1.02–1.52). The other associations did not vary when stratifying by age at baseline and adherence to mammography recommendations. In conclusion, multi-morbidity was not a key factor to help identify patients at an increased risk of breast cancer.

1. Introduction

Breast cancer is the most common female cancer, with 2,088,849 new cases worldwide in 2018, accounting for 11.6% of incident cancer cases [1]. Despite decades of intensive research effort, only about 70% of the disease occurrence is explained by well-established risk factors [2]. Most of the identified risk factors are not readily modifiable [2,3,4], leading to a need for additional research to better understand etiologic processes.
In developed countries, most breast cancer cases are diagnosed among women of middle age or older [5], coinciding with the occurrence of other long-term morbidities [6,7]. Previous studies have suggested associations between breast cancer risk and specific chronic diseases, such as endocrine disorders [8,9], inflammatory conditions [10], autoimmune diseases [11], and cardiovascular diseases (CVDs) [12], especially among postmenopausal women. The underlying mechanisms of these associations could involve shared common physiopathological pathways (e.g., estrogen-related pathways, inflammation pathways) [13,14,15,16], shared genetic predispositions, shared risk factors (e.g., obesity, physical inactivity) [17], and medications (e.g., aspirin) [18].
As people get older, they often develop two or more chronic diseases. With an aging population, the number of people experiencing several multi-morbidities is rising globally [6,7,19,20,21]. In the general population, co-existing morbidities could be classified into common clinically meaningful patterns [22,23]. Sharing underlying biological mechanisms and/or sets of risk factors, the morbidities in the same cluster often interact mutually, which complicates treatments and management and increases the risk of adverse events above and beyond the sum of the risk of individual disease [24]. Being diagnosed with multi-morbidity is also associated with an increased likelihood of being subjected to breast cancer screening [25,26,27], which may lead to increased surveillance of breast cancer incidence. Thus, it is necessary to consider patterns of morbidity, in addition to associations with single chronic diseases, with breast cancer risk.
However, to date, there is no epidemiological evidence as to whether and to what extent breast cancer risk varies according to different patterns of morbidity. In this context, our study aimed to investigate the association between the number of morbidities and patterns of morbidity and the risk of female breast cancer.

2. Materials and Methods

2.1. Data Source and Study Design

The UK Biobank is a prospective population-based cohort that recruited 273,375 women, aged 40 to 69 years, from March 2006 to July 2010 [28]. Individuals were invited to participate on a voluntary basis and provided electronic informed consent for data provision and linkage. The baseline data assessment included self-reported data on personal and family medical history, lifestyle, hormone-related factors, and sociodemographic characteristics. Additional anthropometric measurements were performed. The cohort additionally retrieved individual information from the national cancer and death registries.

2.2. Study Population

We excluded women with any cancer diagnosis prior to baseline except non-melanoma skin cancer (n = 29,332), women who underwent a mastectomy prior to baseline (n = 2457), and women with less than one year of follow-up (n = 2150), leaving 239,436 women in the final analysis (Figure 1).

2.3. Baseline Morbidity Identification

Based on an established list of morbidities, which was originally designed by Barnett et al. [19] to measure multi-morbidity in a large population-based dataset and subsequently validated in the UK Biobank cohort (Appendix A, Table A1) [29], we defined 35 morbidities based on baseline self-reported health conditions (Figure 2). For each woman, we computed the total number of morbidities and categorized them as none/one/multi-morbidity (at least two morbidities).

2.4. Breast Cancer Ascertainment

We defined breast cancer as a diagnosis of invasive or in situ breast cancer, using the international classification of diseases (ICD) versions 9 and 10 (ICD-10: C50 or D05; ICD-9: 174 or 2330). We considered only breast cancer cases that were the first cancer diagnosed.

2.5. Baseline Confounding Factors

All confounding factors (age at menarche, age at menopause, menopausal hormone therapy use, oral contraceptive use, parity and age at first birth, body mass index (BMI), ethnicity, Townsend score, level of physical activity, alcohol consumption) were measured/collected at baseline. We selected well-established breast cancer risk factors based on previous studies [30,31]. We also selected variables that were statistically significantly associated with both morbidity and breast cancer risk (p-value < 0.05) as confounders if their inclusion in the age-adjusted Cox models changed the hazard ratio by 5% or more [32]. See Appendix A, Table A2 for more details on the variables of interest, their definition, and information sources.

2.6. Statistical Analysis

2.6.1. Multiple Correspondence Analysis (MCA) and Cluster Analysis (See Appendix B)

Among 35 baseline self-report morbidities, we included only morbidities with a prevalence of more than 1% (Figure 2) to obtain stable clustering results [33]. We used MCA [34,35] and cluster analysis to identify morbidity patterns. MCA can produce the input data for the cluster analysis, while reducing noise by excluding unnecessary dimensions that do not contribute significantly to the cluster’s classification. We determined the optimal number of dimensions to extract based on the elbow rule in the Scree plot [34] and Horn’s parallel analysis for common factor analysis [36].
Using the numerical outputs of the MCA, we performed agglomerative hierarchical clustering (AHC) preceded by K-means clustering with 2000 initial cluster seeds [37], through the HCPC function of the Factominer package in R. This method allowed us to reduce the required memory allocations [38,39]. We considered the distance between points in Euclidean space as the distance metric [40], and Ward’s method was used to create homogeneous clusters by fusion [36]. We chose the optimal number of clusters, i.e., the identified morbidity patterns and assessed cluster quality, using the Davies–Bouldin [41] and the GAP indexes [42]. The optimal number of clusters was the one that corresponded to the minimum value of the Davies–Bouldin index and to the maximum Gap statistics index.
Within each cluster, we computed the observed/expected ratios (“O/E-ratios”) for each single morbidity, i.e., the ratio between the prevalence of a given condition in a cluster and its prevalence in the overall study population. Similarly, we computed the exclusivity of each single morbidity, i.e., the number of individuals that had a given morbidity in a cluster over the number of individuals with the same morbidity in the whole study population. A morbidity was considered part of a given morbidity cluster when its O/E-ratio was ≥2 and its exclusivity was ≥25% [23,43]. We named the morbidity patterns based on the predominant morbidities in the clusters.

2.6.2. Association among the Number of Morbidities, Morbidity Patterns, and Breast Cancer Risk

The follow-up time started at the date of first registration at a UK Biobank center and ended at the date of the first cancer diagnosis (any cancer diagnosis, except non-melanoma skin cancer) or mastectomy, death, loss to follow-up, or 31 March 2016, whichever came first. We fitted Cox proportional hazard models to estimate hazard ratios and 95% confidence intervals (95%CIs) of breast cancer risk associated with each single pre-existing baseline morbidity included in the cluster analysis, the number of morbidities, and the morbidity patterns. The timescale was the follow-up time.
We graphically assessed the proportional hazards assumption using scaled Schoenfeld residuals plots and log linearity assumption (for quantitative covariates) using Martingale residuals plots and deviance residuals plots. The final multivariable Cox models were adjusted for age at baseline, age at menarche, age at menopause, menopausal hormone therapy use, oral contraception use, parity and age at first birth, BMI, ethnicity, the Townsend score, level of physical activity, and alcohol consumption.
We tested the modifying effects of age at baseline, the adherence to the recommendations for breast cancer screening, the BMI, the socioeconomic status, the physical activity level, and the menopause status at baseline with the likelihood ratio test. We conducted several sensitivity analyses: (i) we restricted analyses to menopausal women; (ii) we considered only invasive breast cancer as the outcome; (iii) we used the attained age as the timescale; (iv) we considered death and diagnosis of non-breast cancer as competing risks, using sub-distribution hazards models [44]; (v) we extracted 11 MCA dimensions, which accounted for more than 70% of the total variability among the study population, as recommended by Higgs [45]; we also extracted all dimensions, assuming they were all significant, and kept different numbers of clusters (3 and 4 clusters) with both 11 and all dimensions extracted.
All statistical analyses were performed using R version 4.1.0.

3. Results

In the study population, the median age at baseline was 57.7 years (interquartile range [IQR]: 50.2, 63.2). At least one morbidity was present in 58.4% of women at baseline, and the prevalence of multi-morbidity was 25.8%. Hypertension was the most prevalent morbidity (23.1%), followed by painful conditions (17.2%) and asthma (12.3%). The prevalence of obesity was 23.5%, and 23.5% of women had menopause after the age of 51 at baseline. Most women were postmenopausal (73.5%) and were adherent to breast cancer screening recommendations (66.6%) at baseline, as assessed at recruitment (Table 1, Figure 2). During a median follow-up time of 7.1 years (IQR: 6.4, 7.8), 5,326 women developed breast cancer (2.0%).

3.1. Description of Morbidity Patterns

We considered the first five MCA dimensions (see Supplementary, Figures S1–S3), which explained 39% of the total variance, as input to the clustering algorithms. We identified five baseline morbidity patterns (see Supplementary, Figures S4 and S5 & Table S1), named as follows: Pattern 1—no-predominant morbidity, pattern 2—psychiatric morbidities, pattern 3—respiratory/immunological morbidities, pattern 4—cardiovascular/metabolic morbidities, pattern 5—unspecific morbidities (see Table 1).

3.1.1. Pattern 1: No-Predominant Morbidity [n = 159,083 (66.4%), 3534 Breast Cancer Cases (2.0% of Cases)]

The median age at baseline was 57.4 years (IQR: 49.9, 63.0), and the median follow-up time was 7.1 years (IQR: 6.4, 7.8). There was no morbidity with an O/E ratio ≥ 2. The main features of this pattern were the low rate of multi-morbidity (6.9%) and the high rate of the absence of morbidity (62.6%).

3.1.2. Pattern 2: Psychiatric Morbidities [n = 16,627 (7.0%), 381 Breast Cancer Cases (2.0% of Cases)]

The median age at baseline was 55.7 years (IQR: 48.7, 61.7), and the median follow-up time was 7.0 years (IQR: 6.3, 7.8). Women with this pattern were predominantly diagnosed with anxiety and depression disorders.

3.1.3. Pattern 3: Respiratory/Immunological Morbidities [n = 27,920 (11.7%), 611 Breast Cancer Cases (2.0% of cases)]

The median age at baseline was 56.7 years (IQR: 49.1, 62.8), and the median follow-up time was 7.1 years (IQR: 6.4, 7.8). Women with this pattern were predominantly diagnosed with psoriasis/eczema, COPD, and asthma.

3.1.4. Pattern 4: Cardiovascular/Metabolic Morbidities [n = 11,041 (4.6%), 246 Breast Cancer Cases (2.0% of cases)]

The median age at baseline was 62.6 years (IQR: 57.2, 66.4), and the median follow-up time was 7.0 years (IQR: 6.3, 7.8). Women with this pattern were predominantly diagnosed with diabetes, stroke, and coronary–heart disease. The main features of this pattern were the high proportions of elderly (about 65% were 65 years or older at baseline), multi-morbidity (96.6%), and deprived people (37.1% of women with this pattern were in the quintile with the highest levels of deprivation).

3.1.5. Pattern 5: Unspecific Morbidities [n = 24,765 (10.3%), 554 Breast Cancer Cases (2.0%)]

The median age at baseline was 59.2 years (IQR: 51.9, 64.0), and the median follow-up time was 7.1 years (IQR: 6.4, 7.8). Women with this pattern were predominantly diagnosed with migraine, diverticular intestine disease, inflammatory bowel disease, rheumatoid disease, and threated dyspepsia.

3.2. Breast Cancer Risk According to the Number of Morbidities and Morbidity Patterns

In both age-adjusted and fully adjusted models, no significant association was found between either the number of morbidities or any morbidity pattern and breast cancer risk, but there was a 12% increased risk associated with self-reported depression (Table 2 and Table 3). The results did not vary significantly with age at baseline (p-value interaction = 0.43 and 0.07, for the analyses on the number of morbidities and morbidity patterns, respectively) and adherence to recommendations for breast cancer screening among women aged 50 and older (p-value interaction = 0.44 and 0.84, for the analyses on the number of morbidities and morbidity patterns, respectively), although we found an increased risk among women aged of up to 50 years in the psychiatric morbidities pattern (HR= 1.25; 95%CI: 1.02–1.52) (Figure 3 and Figure 4). The results remained consistent after accounting for competing risks (Table 4), when considering attained age as the timescale in the Cox models (Supplementary, Table S2) and in other sensitivity analyses (see Supplementary, Tables S3 and S4).

4. Discussion

Among female participants in the UK Biobank cohort, 58.4% had at least one chronic disease, while 25.8% had two or more simultaneous morbidities. Hypertension was the most prevalent disease (23.1%) at baseline. We found five morbidity patterns: no-predominant morbidity, psychiatric morbidities, respiratory/immunological morbidities, cardiovascular/metabolic morbidities, and unspecific morbidities. There was a 1.12-fold increased risk among women who self-reported depression and a 25% increased risk of breast cancer associated with a psychiatric morbidity pattern compared to that with the no-predominant morbidity pattern, among women younger than 50 only. We did not observe other significant associations between either the number of morbidities or any morbidity pattern and the risk of breast cancer, which did not vary according to adherence to breast cancer screening recommendations, socioeconomic status, BMI, physical activity level, or menopausal status.
Despite heterogeneous findings in previous studies on morbidities across different populations and settings, several morbidity patterns often emerge in the literature, which were also observed in our study [22,23,46,47]. The pattern of cardiovascular/metabolic morbidities has been extensively described previously, as there are established etiologic associations among diabetes, stroke, heart failure, and heart disease, with an interlinked pathophysiology and common risk factors, such as obesity, physical inactivity, and smoking [48]. For the pattern of psychiatric morbidities, although little is known about the pathogenesis of depression and anxiety, these two frequent mental illnesses share a largely overlapping set of risk factors with breast cancer, including female sex, genetic predisposition, family history, and environmental influence (childhood adversity, low socioeconomic status) [49,50]. Depression and anxiety are also common coexisting conditions among patients with chronic comorbidities, including cancer [51,52]. Consistent with our findings, a recent nationwide population-based study has shown that mental disorders were associated with a subsequent higher risk of cancer, although the causal link remains a topic of debate [52]. The diseases included in the respiratory pattern, such as chronic obstructive pulmonary disease and asthma, involve a prolonged inflammatory response and the sharing of risk factors, such as smoking, an unhealthy diet, physical inactivity, and high alcohol consumption. However, combinations among asthma, COPD, and psoriasis and eczema are less common. Thus, these patterns found in our clustering analysis not only represent a clinically relevant morbidity status in women in the UK Biobank cohort but also reflect distinct profiles of (known or unknown), shared genetics, and behavioral and environmental risk factors, both of which might increase the risk of developing cancer.
Indeed, to our knowledge, our study is the first to investigate the association between morbidity patterns and breast cancer risk. We found no association between either the number of morbidities or morbidity patterns and breast cancer risk, regardless of the women’s age at baseline, and socioeconomic characteristics, apart from an increased risk among women aged less than 50 having multiple psychiatric diseases. Analyses stratified based on adherence to breast cancer screening recommendations did not modify our main results, suggesting that surveillance bias is not an important modifying factor in the association between breast cancer risk and morbidities. Previously, there was only a case-control study reporting results on the association between multi-morbidity and breast cancer risk. The findings indicated that an increasing number of morbidities measured with the Charlson comorbidity index (CCI) was associated with an increasing breast cancer risk (46,324 cases) after a 10-year follow-up of women aged 45–85, but no association was found for individual morbidities [53]. However, they were not able to control for confounding factors other than age at baseline and to account for surveillance bias. For comparison purposes, we applied the same methods in an additional analysis by using the CCI (Tables S5 and S6), and we did not find a significant association between the Charlson morbidity number and breast cancer risk after adjusting for well-known risk factors.
There are several hypotheses to explain the null results. First, women with morbidity could experience other serious long-term outcomes before a breast cancer diagnosis. Indeed, when accounting for death and malignancies other than breast cancer as competing risks, we found that compared to that in women with no predominant morbidity, women with other patterns were more likely to die and/or to be diagnosed with other cancers. This is particularly pronounced among women with cardiovascular/metabolic and respiratory/immunological morbidities. Second, given the different biologic characteristics of divergent breast cancer subtypes [54] and the complexity of multi-morbidity mechanisms and risk factors, the risk estimations could vary across individual associations, and the possible opposing effects could drive the combined estimates toward null. For instance, BMI, a common risk factor of various morbidities, is strongly associated with hormone receptor-positive tumors, but not a triple-negative or core basal phenotype [55]. A high BMI is a risk factor of postmenopausal breast cancer, but a protective factor of premenopausal breast cancer. Type 2 diabetes is an independent risk factor of breast cancer risk in postmenopausal women, but no increased risk was observed for premenopausal women [8]. In our study, when restricting analyses to postmenopausal women only, the null associations remained consistent. Previous large prospective cohorts reported that low socioeconomic positions, a contributing factor of psychiatric morbidities, were found to be associated with a lower risk of ER+ breast cancer but a higher risk of the ER- subtype [56,57]. Meanwhile, adverse life events, such as childhood abuse and divorce, were associated with a higher risk of ER+, but not ER-, breast cancer [57,58]. Third, our null results could also suggest that the underlying common biological pathways among morbidities in an individual pattern and their shared risk factors were not a key factor explaining breast cancer risk after accounting for established breast cancer risk factors.
Strength and limitations: The UK Biobank cohort is a large population-based cohort with a high follow-up rate and important number of breast cancer cases. The cohort includes a wide range of information on personal medical history, reproductive factors, lifestyle factors, socioeconomic status, and family medical history, with low levels of missing data. Nevertheless, there are several limitations that must be acknowledged. Assuming that the prevalence of having at least one morbidity in women in the UK Biobank cohort is slightly lower than what has been found (42.2%, 33.8%) in previous studies of Barnett and Gondek, respectively (since these studies have included data of both women and men in the analyses, which could lead to a potential underestimation of the morbidity prevalence), this suggests the occurrence of “healthy” volunteer bias (i.e., UK Biobank participants are more likely to be in good health conditions than the general population) [59,60]. However, since our study focuses on investigating breast cancer risk in relation to morbidity and not on estimating disease prevalence rates and many people with a wide range of morbidities and risk factors are included in the cohort, the risk estimations are unlikely to be biased [59,60]. We used self-reported health condition data, which were not externally validated, and the UK Biobank did not include information on morbidity severity. There was no longitudinal updated morbidity status and thus no possibility to study changes in morbidity patterns during follow-up. We also missed details on the breast cancer stage, grade, and receptor status. This did not allow us to further study the surveillance biases related to the disease stage and grade or to investigate potential pathways related to tumor receptor status.

5. Conclusions

Female participants in the UK Biobank cohort can be classified into five morbidity patterns: no-predominant morbidity, psychiatric morbidities, respiratory/immunological morbidities, cardiovascular/metabolic morbidities, and unspecific morbidities. We found a significant increased risk among women aged younger than 50 with a psychiatric diseases pattern, but there was no other significant association among the number of morbidities, the morbidity patterns, and the risk of breast cancer in this population. Our findings suggest that multimorbidity is not a decisive factor to help identify patients at increased risk of breast cancer.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/cancers15041165/s1, Figure S1: Individuals’ point cloud (a) on the first two and (b) on the first and third axes. Figure S2: Morbidity categories’ point cloud (a) on the first two and (b) on the first and third axes. Figure S3: suggested number of MCA dimensions: (a) Scree plot; (b) Horn’s parallel analysis. Figure S4: Suggested number of morbidity clusters: (a) Gap-statistic method; (b) elbow method. Figure S5: Dendrogram of five morbidity clusters solution. Table S1: Suggested number of morbidity patterns based on the Davies-Bouldin index. Table S2: Cox models using attained age as timescale. Table S3: Cox models using invasive breast cancer only as outcome. Table S4: Others modified effects. Table S5: Association between breast cancer risk and the preexisting Charlson single pre-existing diseases at baseline. Table S6: Association between Charlson comorbidity index at baseline and breast cancer risk.

Author Contributions

Conceptualization, T.-V.-T.T.; methodology, T.-V.-T.T. and A.M.S.H.; statistical analysis, T.-V.-T.T. and A.M.S.H.; supervision, T.-V.-T.T. and N.M.Y.J.; original drafting of the paper, A.M.S.H., T.-V.-T.T.; writing-review-and editing, A.M.S.H., R.S.A., F.d.V., M.-C.B.-R., N.M.Y.J. and T.-V.-T.T.; interpretation of the results, A.M.S.H., R.S.A., F.d.V., M.-C.B.-R., N.M.Y.J. and T.-V.-T.T. All authors have read and agreed to the published version of the manuscript.

Funding

Afi HENYOH received an internship stipend from INSERM. Thi-Van-Trinh TRAN received a doctoral grant from the Paris Sud-Paris Saclay University.

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki and was performed under generic ethical approval obtained by the UK Biobank from the National Health Service National Research Ethics Service (approval letter ref 16/NW/0274, 13 May 2016).

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

This work has been conducted using the UK Biobank Resource under Application Number 35032. Bona-fide researchers can apply to use the UK Biobank dataset by registering and applying at http://www.ukbiobank.ac.uk/register-apply accessed on 1 March 2022.

Conflicts of Interest

The authors declare no conflict of interest.

Appendix A

Table A1. Baseline long-term health condition groupings.
Table A1. Baseline long-term health condition groupings.
Morbidity ^Conditions Included
1. Painful conditions *Back pain
Joint pain
Headaches (not migraine)
Sciatica
Plantar fasciitis
Carpal tunnel syndrome
Fibromyalgia
Arthritis
Shingles
Disc problem
Prolapsed disc/slipped disc
Spine arthritis/spondylitis
Ankylosing spondylitis
Back problem
Osteoarthritis
Gout
Cervical spondylosis
Trigeminal neuralgia
Disc degeneration
Trapped nerve/compressed nerve
2. HypertensionHypertension
Essential hypertension
3. Depression *Depression
Postnatal depression
4. AsthmaAsthma
5. Coronary heart diseaseHeart attack/MI
Angina
6. Treated dyspepsiaGastro-esophageal reflux (GORD)/gastric reflux
Esophagitis/Barrett’s esophagus
Gastric stomach ulcers
Gastric erosions/gastritis
Duodenal ulcer
Dyspepsia/indigestion
Hiatus hernia
Helicobacter pylori
7. DiabetesDiabetic nephropathy
Diabetic neuropathy/ulcers
Diabetes
Type 1 diabetes
Type 2 diabetes
Diabetic eye disease
8. Thyroid disordersThyroid problem (not cancer)
Hyperthyroidism/thyrotoxicosis
Hypothyroidism/myxedema
Graves’ disease
Thyroid goitre
Thyroiditis
9. Rheumatoid arthritis, other inflammatory polyarthropathies, systemic connective tissue disorders and systemic autoimmune disordersMyositis/myopathy
Systemic lupus erythematosus
Connective tissue disorder
Sjogren’s syndrome/sicca syndrome
Dermatopolymyositis
Scleroderma/systemic sclerosis
Rheumatoid arthritis
Psoriatic arthropathy
Dermatomyositis
Polymyositis
Polymyalgia rheumatica
Malabsorption/celiac disease
10. Chronic obstructive pulmonary disease (COPD)COPD/chronic obstructive airways disease
Emphysema/chronic bronchitis
Emphysema
11. Anxiety, other neurotic, stress-related, and somatoform disorders *Anxiety/panic attacks
Nervous breakdown
Post-traumatic stress disorder
Obsessive compulsive disorder
Stress
Insomnia
Psychological/psychiatric problem
12. Irritable bowel syndromeIrritable bowel syndrome
13. Alcohol problems *Alcohol dependency
Alcoholic liver disease/alcoholic cirrhosis
14. Other psychoactive substance abuse *Opioid dependency
Other substance abuse/dependency
15. Treated constipationConstipation
16. Stroke and transient ischemic attack (TIA)Stroke
TIA
Subarachnoid hemorrhage
Brain hemorrhage
Ischemic stroke
17. Chronic kidney diseasePolycystic kidney
Diabetic nephropathy
Renal/kidney failure
Renal failure requiring dialysis
Renal failure not requiring dialysis
Kidney nephropathy
Immunoglobulin A (IgA) nephropathy
18. Diverticular disease of intestineDiverticular disease/diverticulitis
19. Atrial fibrillationAtrial fibrillation
20. Peripheral vascular diseasePeripheral vascular disease
Leg claudication/intermittent claudication
21. Heart failureCardiomyopathy
Hypertrophic cardiomyopathy
Heart failure/pulmonary edema
22. Prostate disordersProstate problem (not cancer)
Enlarged prostate
Benign prostatic hypertrophy
23. GlaucomaGlaucoma
24. EpilepsyEpilepsy
25. DementiaDementia/Alzheimer/cognitive impairment
26. Schizophrenia (and related non-organic psychosis) and bipolar disorder *Schizophrenia
Mania/bipolar disorder/manic depression
27. Psoriasis or eczemaEczema/dermatitis
Psoriasis
28. Inflammatory bowel diseaseInflammatory bowel disease
Crohn’s disease
Ulcerative colitis
29. MigraineMigraine
30. Chronic sinusitisChronic sinusitis
31. Anorexia or bulimia *Anorexia, bulimia/other eating disorder
32. BronchiectasisBronchiectasis
33. Parkinson’s diseaseParkinson’s disease
34. Multiple sclerosisMultiple sclerosis
35. Viral HepatitisInfective/viral hepatitis
Hepatitis B
Hepatitis C
Hepatitis D
Hepatitis E
36. Chronic liver diseaseEsophageal varices
Non infective hepatitis
Liver failure/cirrhosis
Primary biliary cirrhosis
37. Osteoporosis ~Osteoporosis
38. Chronic fatigue syndrome ~Chronic fatigue syndrome
39. Endometriosis ~Endometriosis
40. Meniere disease ~Meniere disease
41. Pernicious Anemia ~Pernicious anemia
42. Polycystic ovaries ~Polycystic ovaries
43. CancerLifetime diagnosis
^ Self-report lifetime diagnosis by doctor recorded by nurse-led interview (UK Biobank data field 20002), except cancer diagnosis that was reported by touch-screen questionnaire (UK Biobank data field 2453). The list of disease groupings was based on Barnett K, Mercer SW, Norbury M, Watt G, Wyke S, Guthrie B: Epidemiology of multimorbidity and implications for health care, research, and medical education: a cross-sectional study. Lancet 2012, 380(9836):37–43 [19]. ~ Plus other conditions considered long-term, requiring medication, and that had a prevalence of ≥0.1% in the whole UK Biobank cohort. * Painful and psychiatric conditions were not included in the morbidity count for this study; this resulted in a total of 36 morbidities included.
Table A2. Definition of confounding factors and effect modifiers.
Table A2. Definition of confounding factors and effect modifiers.
Risk FactorsCodingInformation SourceTesting for
Confounding Effect
Testing for
Modification Effect
Socio-demographic and economic characteristics
Age at baselineContinuousSR-QYesYes
OccupationAdministrative and Secretarial Occupations
Associate Professional and Technical Occupations Elementary Occupations
Managers and Senior Officials
Personal Service Occupations
Process, Plant, and Machine Operatives
Professional Occupations
Sales and Customer Service Occupations
Skilled Trades Occupations
Unknown
SR-QYesNo
RaceAsian
Black and Caribbean
White
Other/Unknown
SR-QYesNo
Townsend scoreContinuousUK data serviceYesYes
Hormone-related factors
Age at menarcheContinuousSR-QYesNo
Age at menopauseStill had periods
Had menopause before the age of 45 years
Had menopause between the age of 45 and 54
Had menopause after the age of 55
SR-QYesYes
Menopausal hormone therapy useNever
Ever, less than 5-year duration
Ever, 5 years and longer
Ever, unknown duration
Reporting menopause (periods stopped) (SR-Q)OR
Reporting use of menopausal hormone therapy (SR-Q)OR
Undergoing a bilateral oophorectomy (SR-I)OR
≥51 years of age at baseline
YesNo
Oral contraception useNever
Ever, less than 10-year duration;
Ever, at least 10-year duration;
Ever, unknown duration;
Unknown status
SR-QYesNo
Parity and age at first birthNo live birth
At least one birth before age 30
At least one birth after age 30
SR-QYesNo
Health and health care-related factors
BMIContinuousPMYesYes
Level of physical activityLow
Moderate
High
SR-QYesYes
Alcohol consumptionNever
Twice a week or less
Three times a week or more
Unknown status
SR-QYesNo
Adherence to mammography guidelinesNever
Ever, last use since more than 3 years ago
Ever, in the last 3 years
Ever, unknown time of last use
SR-QYesYes
SR-Q: self-reported data from questionnaire, SR-I: self-reported data from trained nurses lead interviews, lead BM: body mass index, PM: physical measurement.

Appendix B

Appendix B.1. Multiple Correspondence Analysis (MCA)

MCA is a data analysis technique used to detect and represent underlying structures in sets of nominal categorical data. It allows identifying groups with similar characteristics and shows, in a multidimensional space, relationships between dichotomous or categorical variables (in our case, morbidities) that would be difficult to observe in a contingency table [34,35]. So far, MCA allows individuals to be directly represented as points (coordinates) in a geometric space through the transformation of original binary data to continuous ones. We performed MCA based on the indicator matrix, also called a complete disjunctive table, which is an individual’s × variables matrix, where the rows represent individual, and the columns are dummy variables representing categories of morbidity variables.

Appendix B.2. Cluster Analysis

  • Agglomerative hierarchical clustering (AHC)
AHC is a commonly used method for cluster analysis in big data research and data mining aiming to establish a hierarchy of clusters [38,39]. As such, HCA attempts to group, inside a heterogeneous population, subjects with similar features into clusters based on similarity or dissimilarity measures. Initially, each observation belongs to one of N disjoint single patterns. The algorithm then sequentially joined the two closest, in terms of the Euclidean distance, until after (N − 1) steps, all observations belong to a single pattern of size N [40].
  • Ward’s method for cluster analysis
This approach is based on a classical sum-square criterion and produces clusters that minimize the decrease in between-cluster inertia, therefore minimizing the within-cluster inertia at each merging step [61]. The hierarchical grouping process can be graphically summarized by a tree-like graphical representation called a dendrogram. Similar objects are linked, and their position in the diagram is determined by the level of similarity/dissimilarity between the objects [62]. Thus, clusters were identified by taking into account the similarity distances between the morbidities among the study population, which subsequently allowed the patterns to be formed.

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Figure 1. Flow chart of the study population.
Figure 1. Flow chart of the study population.
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Figure 2. Morbidities identified among cancer-free UK Biobank women at recruitment.
Figure 2. Morbidities identified among cancer-free UK Biobank women at recruitment.
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Figure 3. Associations between morbidity clusters and breast cancer risk, according to age-groups and the adherence to breast cancer screening recommendations. HR: hazard ratio; CI: confidence interval. The adherence to mammography included only women older than 50 years. The model was adjusted for age at menarche (continuous), age at menopause (still had periods; had menopause before the age of 45 years; had menopause between the age of 45 and 54; had menopause after the age of 55), menopausal hormone therapy use (never; ever, less than 5-year duration; ever, 5 years and longer; ever, unknown duration), oral contraceptive use (never; ever, less than 10-year duration; ever, at least 10-year duration; ever, unknown duration; unknown status), parity and age at first birth (no live birth; at least one birth before age 30; at least one birth after age 30), BMI (continuous), ethnicity (Asian; Black/Caribbean; White; others/unknown), Townsend score (continuous); level of physical activity (low; moderate; high), alcohol consumption (never; twice a week or less; three times a week or more; unknown status).
Figure 3. Associations between morbidity clusters and breast cancer risk, according to age-groups and the adherence to breast cancer screening recommendations. HR: hazard ratio; CI: confidence interval. The adherence to mammography included only women older than 50 years. The model was adjusted for age at menarche (continuous), age at menopause (still had periods; had menopause before the age of 45 years; had menopause between the age of 45 and 54; had menopause after the age of 55), menopausal hormone therapy use (never; ever, less than 5-year duration; ever, 5 years and longer; ever, unknown duration), oral contraceptive use (never; ever, less than 10-year duration; ever, at least 10-year duration; ever, unknown duration; unknown status), parity and age at first birth (no live birth; at least one birth before age 30; at least one birth after age 30), BMI (continuous), ethnicity (Asian; Black/Caribbean; White; others/unknown), Townsend score (continuous); level of physical activity (low; moderate; high), alcohol consumption (never; twice a week or less; three times a week or more; unknown status).
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Figure 4. Associations between morbidity clusters and breast cancer risk, according to age groups and the adherence to breast cancer screening recommendations. HR: hazard ratio; CI: confidence interval. The adherence to mammography included only women older than 50 years. The model was adjusted for age at menarche (continuous), age at menopause (still had periods; had menopause before the age of 45 years; had menopause between the age of 45 and 54; had menopause after the age of 55), menopausal hormone therapy use (never; ever, less than 5-year duration; ever, 5 years and longer; ever, unknown duration), oral contraceptive use (never; ever, less than 10-year duration; ever, at least 10-year duration; ever, unknown duration; unknown status), parity and age at first birth (no live birth; at least one birth before age 30; at least one birth after age 30), BMI (continuous), ethnicity (Asian; Black/Caribbean; White; others/unknown), Townsend score (continuous); level of physical activity (low; moderate; high), alcohol consumption (never; twice a week or less; three times a week or more; unknown status).
Figure 4. Associations between morbidity clusters and breast cancer risk, according to age groups and the adherence to breast cancer screening recommendations. HR: hazard ratio; CI: confidence interval. The adherence to mammography included only women older than 50 years. The model was adjusted for age at menarche (continuous), age at menopause (still had periods; had menopause before the age of 45 years; had menopause between the age of 45 and 54; had menopause after the age of 55), menopausal hormone therapy use (never; ever, less than 5-year duration; ever, 5 years and longer; ever, unknown duration), oral contraceptive use (never; ever, less than 10-year duration; ever, at least 10-year duration; ever, unknown duration; unknown status), parity and age at first birth (no live birth; at least one birth before age 30; at least one birth after age 30), BMI (continuous), ethnicity (Asian; Black/Caribbean; White; others/unknown), Townsend score (continuous); level of physical activity (low; moderate; high), alcohol consumption (never; twice a week or less; three times a week or more; unknown status).
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Table 1. Characteristics of the overall study population and the identified baseline morbidity patterns.
Table 1. Characteristics of the overall study population and the identified baseline morbidity patterns.
CharacteristicsOverall Study Population
N = 239,436
Pattern 1: No-Predominant Morbidity
N = 159,083
Pattern 2: Psychiatric Morbidities
N = 16,627
Pattern 3: Respiratory/Immunological Morbidities
N = 27,920
Pattern 4:
Cardiovascular/Metabolic Morbidities
N = 11,041
Pattern 5: Unspecific Morbidities
N = 24,765
p-Value *
Year of follow-up, median (IQR)7.1 (6.4, 7.8)7.1 (6.4, 7.8)7.0 (6.3, 7.8)7.1 (6.4, 7.8)7.0 (6.3, 7.8)7.1 (6.4, 7.8)<0.001
Breast cancer cases, n (%)5326 (2)3534 (2)381 (2)611 (2)246 (2)554 (2)0.97
Number of comorbid conditions, n (%) <0.001
None99,614 (41.6)99,614 (62.6)0 (0.0)0 (0.0)0 (0.0)0 (0.0)
One77,994 (32.6)48,489 (30.5)6260 (37.6)14,283 (51.2)379 (3.4)8583 (34.7)
Two38,424 (16.0)10,145 (6.4)5974 (35.9)9156 (32.8)4717 (42.7)8432 (34.0)
Three and more23,404 (9.8)835 (0.5)4393 (26.4)4481 (16.0)5945 (53.8)7750 (31.3)
Morbidity, n (%)
Stroke and transient ischemic attack (TIA)3149 (1.3)833 (0.5)90 (0.5)181 (0.6)1761 (15.9)284 (1.1)<0.001
Diabetes8122 (3.4)1429 (0.9)63 (0.4)282 (1.0)5924 (53.7)424 (1.7)<0.001
Coronary heart disease5566 (2.3)796 (0.5)53 (0.3)329 (1.2)3978 (36.0)410 (1.7)<0.001
Migraine9947 (4.2)247 (0.2)940 (5.7)686 (2.5)102 (0.9)7972 (32.2)<0.001
Diverticular disease of intestine3048 (1.3)0 (0.0)10 (0.1)109 (0.4)247 (2.2)2682 (10.8)<0.001
Irritable bowel syndrome7622 (3.2)32 (0.0)642 (3.9)195 (0.7)276 (2.5)6477 (26.2)<0.001
Rheumatoid arthritis6778 (2.8)0 (0.0)81 (0.5)201 (0.7)4 (0.0)6492 (26.2)<0.001
Treated dyspepsia17,733 (7.4)6427 (4.0)1704 (10.2)2053 (7.4)1807 (16.4)5742 (23.2)<0.001
Psoriasis or eczema8344 (3.5)0 (0.0)773 (4.6)5823 (20.9)190 (1.7)1558 (6.3)<0.001
Chronic obstructive respiratory disease (COPD)3355 (1.4)0 (0.0)7 (0.0)3333 (11.9)2 (0.0)13 (0.1)<0.001
Asthma29,541 (12.3)0 (0.0)2311 (13.9)21,708 (77.8)2473 (22.4)3049 (12.3)<0.001
Anxiety4964 (2.1)0 (0.0)4460 (26.8)113 (0.4)216 (2.0)175 (0.7)<0.001
Depression16,368 (6.8)0 (0.0)13,362 (80.4)424 (1.5)1157 (10.5)1425 (5.8)<0.001
Thyroid disorders22,718 (9.5)13,277 (8.3)1776 (10.7)2213 (7.9)2806 (25.4)2646 (10.7)<0.001
Hypertension55,223 (23.1)31,013 (19.5)3647 (21.9)6112 (21.9)8505 (77.0)5946 (24.0)<0.001
Pain conditions41,258 (17.2)21,363 (13.4)3665 (22.0)4767 (17.1)3132 (28.4)8331 (33.6)<0.001
Age at baseline, median (IQR)57.7 (50.2, 63.2)57.4 (49.9, 63.0)55.7 (48.7, 61.7)56.7 (49.1, 62.8)62.6 (57.2, 66.4)59.2 (51.9, 64.0)<0.001
Family history of breast cancer, n (%)25,330 (10.6)16,858 (10.6)1765 (10.6)2885 (10.3)1102 (10.0)2720 (11.0)0.035
BMI, n (%) <0.001
<18.51803 (0.8)1215 (0.8)115 (0.7)225 (0.8)23 (0.2)225 (0.9)
18.5–2592,857 (38.8)66,570 (41.8)5644 (33.9)10,139 (36.3)1547 (14.0)8957 (36.2)
25–3087,381 (36.5)58,431 (36.7)6067 (36.5)10,161 (36.4)3581 (32.4)9141 (36.9)
>3056,150 (23.5)31,992 (20.1)4725 (28.4)7282 (26.1)5799 (52.5)6352 (25.6)
Unknown1245 (0.5)875 (0.6)76 (0.5)113 (0.4)91 (0.8)90 (0.4)
Adherence to breast cancer screening, n (%) <0.001
<50 years of age58,722 (24.5)40,371 (25.4)4902 (29.5)7745 (27.7)873 (7.9)4831 (19.5)
>50 years of age, >3 years ago7929 (3.3)5072 (3.2)554 (3.3)889 (3.2)545 (4.9)869 (3.5)
>50 years of age, in the last 3 years159,407 (66.6)104,789 (65.9)10,158 (61.1)17,761 (63.6)8937 (80.9)17,762 (71.7)
>50 years of age, never8013 (3.3)5384 (3.4)631 (3.8)943 (3.4)348 (3.2)707 (2.9)
>50 years of age, unknown5365 (2.2)3467 (2.2)382 (2.3)582 (2.1)338 (3.1)596 (2.4)
Age at menarche, median (IQR)13.0 (12.0, 14.0)13 (12.0, 14.0)13 (12.0, 14.0)13.0 (12.0, 14.0)13 (12.0, 14.0)13 (12.0, 14.0)<0.001
Age at menopause µ, median (IQR)50.0 (47.0, 52.0)50.0 (47.0, 52.0)50.0 (45.5, 52.0)50.0 (46.0, 52.0)50.0 (45.0, 52.0)50.0 (46.0, 52.0)<0.001
Menopause status at baseline, n (%) <0.001
Still had periods63,488 (26.5)44,275 (27.8)4979 (29.9)8152 (29.2)951 (8.6)5131 (20.7)
Had menopause before the age of 4525,659 (10.7)14,768 (9.3)2095 (12.6)3356 (12.0)2024 (18.3)3416 (13.8)
Had menopause between the age of 45 and 54129,114 (53.9)85,911 (54.0)8332 (50.1)14,084 (50.4)6796 (61.6)13,991 (56.5)
Had menopause after the age of 5421,175 (8.8)14,129 (8.9)1221 (7.3)2328 (8.3)1270 (11.5)2227 (9.1)
Menopausal hormone therapy use µ, n (%) <0.001
Never85,613 (48.7)59,734 (52.0)4572 (39.3)8935 (45.2)4485 (44.4)7887 (40.2)
Ever, less than 5 years duration 31,000 (17.6)19,322 (16.8)2553 (21.9)3683 (18.6)1620 (16.1)3822 (19.5)
Ever, 5 years and longer duration47,233 (26.8)28,799 (25.1)3496 (30.0)5759 (29.1)2898 (28.7)6281 (32.0)
Ever, unknown duration11,229 (6.4)6386 (5.6)975 (8.4)1314 (6.6)1004 (9.9)1550 (7.9)
Unknown status874 (0.5)567 (0.5)52 (0.4)77 (0.4)84 (0.8)94 (0.5)
Oral contraception use, n (%) <0.001
Never44,767 (18.7)29,175 (18.3)2795 (16.8)4818 (17.3)3147 (28.5)4832 (19.5)
Ever, less than 10 years duration87,270 (36.4)57,671 (36.3)5929 (35.7)10,134 (36.3)4074 (36.9)9462 (38.2)
Ever, 10 years and longer duration84,462 (35.3)57,626 (36.2)6117 (36.8)10,315 (36.9)2505 (22.7)7899 (31.9)
Ever, unknown duration22,542 (9.4)14,354 (9.0)1758 (10.6)2628 (9.4)1270 (11.5)2532 (10.2)
Unknown status395 (0.2)257 (0.2)28 (0.2)25 (0.1)45 (0.4)40 (0.2)
Parity and age at first birth, n (%) <0.001
None of live birth44,601 (18.6)29,572 (18.6)3575 (21.5)5497 (19.7)1614 (14.6)4343 (17.5)
At least one birth before 30150,386 (62.8)98,115 (61.7)10,088 (60.7)17,341 (62.1)8183 (74.1)16,659 (67.3)
At least one birth after age 3043,302 (18.1)30,569 (19.2)2910 (17.5)5003 (17.9)1154 (10.5)3666 (14.8)
Unknown1147 (0.5)827 (0.5)54 (0.3)79 (0.3)90 (0.8)97 (0.4)
Levels of physical activities, n (%) <0.001
Low76,618 (32.0)47,554 (29.9)5964 (35.9)9211 (33.0)4867 (44.1)9022 (36.4)
Moderate85,403 (35.7)57,868 (36.4)5758 (34.6)9893 (35.4)3341 (30.3)8543 (34.5)
High77,415 (32.3)53,661 (33.7)4905 (29.5)8816 (31.6)2833 (25.7)7200 (29.1)
Alcohol consumption, n (%) <0.001
Never22,751 (9.5)12,842 (8.1)1952 (11.7)2650 (9.5)2201 (19.9)3106 (12.5)
Once or twice a week or less128,606 (53.7)84,178 (52.9)8816 (53.0)14,979 (53.6)6553 (59.4)14,080 (56.9)
Three times a week or more87,417 (36.5)61,568 (38.7)5819 (35.0)10,247 (36.7)2255 (20.4)7528 (30.4)
Unknown662 (0.3)495 (0.3)40 (0.2)44 (0.2)32 (0.3)51 (0.2)
Ethnicity, n (%) <0.001
White224,792 (93.9)149,010 (93.7)15,960 (96.0)26,260 (94.1)9802 (88.8)23,760 (95.9)
Asia5200 (2.2)3615 (2.3)192 (1.2)558 (2.0)508 (4.6)327 (1.3)
Black and Caribbean4286 (1.8)2975 (1.9)146 (0.9)491 (1.8)427 (3.9)247 (1.0)
Other/unknown5158 (2.2)3483 (2.2)329 (2.0)611 (2.2)304 (2.8)431 (1.7)
Region, n (%) <0.001
England212,190 (88.6)140,684 (88.4)15,006 (90.3)24,840 (89.0)9744 (88.3)21,916 (88.5)
Scotland17,382 (7.3)11,914 (7.5)1022 (6.1)1786 (6.4)837 (7.6)1823 (7.4)
Wales9864 (4.1)6485 (4.1)599 (3.6)1294 (4.6)460 (4.2)1026 (4.1)
Socioeconomic status based on Townsend
Score, n (%)
<0.001
Interquartile 159,168 (24.7)40,773 (25.6)3653 (22.0)6715 (24.1)1904 (17.2)6123 (24.7)
Interquartile 258,909 (24.6)40,010 (25.2)3918 (23.6)6477 (23.2)2333 (21.1)6171 (24.9)
Interquartile 359,853 (25.0)39,856 (25.1)4195 (25.2)6949 (24.9)2708 (24.5)6145 (24.8)
Interquartile 461,506 (25.7)38,444 (24.2)4861 (29.2)7779 (27.9)4096 (37.1)6326 (25.5)
IQR: Interquartile range. * p-value expresses the presence of statistically significant differences among the five morbidity patterns identified (Kruskal–Wallis test for continuous variables, Pearson’s χ2 test for categorical). µ Post-menopausal women only.
Table 2. Association between preexisting single diseases at baseline and breast cancer risk.
Table 2. Association between preexisting single diseases at baseline and breast cancer risk.
Pre-Existing Disease at Baseline Number of Breast Cancer Cases/Person YearsAge-Adjusted Model HR (95%CI)Multivariable Model HR (95%CI)
Hypertension
No3979/1,287,9671.00 (Reference)1.00 (Reference)
Yes1347/383,4171.06 (0.99–1.13)1.03 (0.97–1.11)
Pain condition
No4336/1,386,5651.00 (Reference)1.00 (Reference)
Yes990/284,8201.06 (0.98–1.13)1.04 (0.97–1.12)
Asthma
No4692/1,465,1341.00 (Reference)1.00 (Reference)
Yes634/206,2500.97 (0.89–1.05)0.96 (0.88–1.04)
Thyroid disorders
No4836/1,513,7681.00 (Reference)1.00 (Reference)
Yes490/157,6170.94 (0.85–1.03)0.93 (0.85–1.02)
Treated dyspepsia
No4898/1,548,5511.00 (Reference)1.00 (Reference)
Yes428/122,8341.04 (0.95–1.15)1.04 (0.94–1.15)
Depression
No4927/1,557,5621.00 (Reference)1.00 (Reference)
Yes399/113,8211.13 (1.02–1.26)1.12 (1.01–1.24)
Migraine
No5099/1,601,2761.00 (Reference)1.00 (Reference)
Yes227/70,1091.04 (0.91–1.18)1.05 (0.91–1.19)
Psoriasis
No5131/1,612,5461.00 (Reference)1.00 (Reference)
Yes195/58,8391.06 (0.92–1.22)1.04 (0.90–1.2)
Diabetes
No5138/1,616,0011.00 (Reference)1.00 (Reference)
Yes188/55,3841.02 (0.88–1.18)0.99 (0.85–1.15)
Irritable bowel syndrome
No5157/1,617,6081.00 (Reference)1.00 (Reference)
Yes169/53,7760.98 (0.84–1.15)0.99 (0.85–1.15)
Rheumatoid arthritis
No5181/1,624,0151.00 (Reference)1.00 (Reference)
Yes145/473,6980.92 (0.78–1.09)0.92 (0.78–1.09)
Coronary heart disease
No5227/1,632,7961.00 (Reference)1.00 (Reference)
Yes99/38,5890.72 (0.59–0.88)0.73 (0.60–0.89)
Anxiety
No5221/1,637,2021.00 (Reference)1.00 (Reference)
Yes105/34,1830.97 (0.80–1.18)0.96 (0.79–1.17)
COPD
No5245/1,648,4551.00 (Reference)1.00 (Reference)
Yes81/22,9301.05 (0.84–1.30)1.07 (0.86–1.33)
Stroke
No5260/1,649,8171.00 (Reference)1.00 (Reference)
Yes66/21,5680.89 (0.70–1.14)0.91 (0.71–1.16)
Diverticular disease of intestine
No5258/1,650,1141.00 (Reference)1.00 (Reference)
Yes68/21,2710.92 (0.72–1.17)0.9 (0.71–1.15)
HR: hazard ratio; CI: confidence interval; the fully adjusted model was adjusted for age at baseline (continuous), age at menarche (continuous), age at menopause (still had periods; had menopause before the age of 45 years; had menopause between the age of 45 and 54; had menopause after the age of 55), menopausal hormone therapy use (never; ever, less than 5-year duration; ever, 5 years and longer; ever, unknown duration), oral contraceptive use (never; ever, less than 10-year duration; ever, at least 10-year duration; ever, unknown duration; unknown status), parity and age at first birth (no live birth; at least one birth before age 30; at least one birth after age 30), BMI (continuous), ethnicity (Asian; Black/Caribbean; White; others/unknown), Townsend score (continuous); level of physical activity (low; moderate; high), alcohol consumption (never; twice a week or less; three times a week or more; unknown status).
Table 3. Associations among number of morbidities, morbidity patterns, and breast cancer risk.
Table 3. Associations among number of morbidities, morbidity patterns, and breast cancer risk.
Study Population (n = 239,436)Postmenopausal Women Only (n = 175,949)
CharacteristicsBreast Cancer Cases/Person-
Years
Age-Adjusted Models
HR (95%CI)
Fully Adjusted Models
HR (95%CI)
Breast Cancer Cases/Person YearsAge-Adjusted Models
HR (95%CI)
Fully Adjusted Models
HR (95%CI)
Number of morbidities
No morbidity2131/69,87761.00 (Reference)1.00 (Reference)1451/454,5661.00 (Reference)1.00 (Reference)
One morbidity1736/54,39741.01 (0.95–1.08)1.00 (0.94–1.07)1361/408,9431.02 (0.95–1.10)1 (0.93–1.08)
Multi-morbidities1459/428,6351.04 (0.97–1.02)1.03 (0.96–1.11)1268/359,8441.06 (0.98–1.14)1.02 (0.94–1.1)
Two morbidities911/266,8311.05 (0.97–1.14)1.04 (0.96–1.13)786/218,7801.08 (0.99–1.18)1.04 (0.95–1.14)
3+ morbidities548/161,8041.03 (0.93–1.13)1.01 (0.92–1.12)482/141,0651.02 (092–1.14)0.97 (0.87–1.08)
Morbidity patterns
No-predominant morbidity3534/1,110,9791.00 (Reference)1.00 (Reference)2670/798,5721.00 (Reference)1.00 (Reference)
Psychiatric morbidities381/115,4761.06 (0.95–1.18)1.04 (0.94–1.16)264/80,5751.00 (0.88–1.14)0.98 (0.86–1.11)
Respiratory/immunological morbidities611/195,1290.99 (0.91–1.08)0.98 (0.9–1.07)467/137,5261.02 (0.92–1.12)1.01 (0.91–1.11)
Cardiovascular/metabolic morbidities246/75,8430.94 (0.83–1.07)0.93 (0.81–1.06)232/69,2520.96 (0.84–1.10)0.91 (0.79–1.05)
Unspecific morbidities554/173,9570.98 (0.89–1.07)0.98 (0.89–1.07)447/137,4290.96 (0.87–1.06)0.95 (0.86–1.05)
HR: hazard ratio; CI: confidence interval; the fully adjusted model was adjusted for age at baseline (continuous), age at menarche (continuous), age at menopause (still had periods; had menopause before the age of 45 years; had menopause between the age of 45 and 54; had menopause after the age of 55; others/unknown), Townsend score (continuous); level of physical activity (low; moderate; high), alcohol consumption (never; once or twice a week or less; three times a week or more; unknown status), menopausal hormone therapy use (never; ever, less than 5-year duration; ever, 5 years and longer; ever, unknown duration), oral contraceptive use (never; ever, less than 10-year duration; ever, at least 10-year duration; ever, unknown duration; unknown status), parity and age at first birth (no live birth; at least one birth before age 30; at least one birth after age 30), BMI (continuous), ethnicity (Asian; Black/Caribbean; White).
Table 4. Association between morbidity patterns and breast cancer risk, counting death and first diagnosed non-breast cancer cases as a competing risk.
Table 4. Association between morbidity patterns and breast cancer risk, counting death and first diagnosed non-breast cancer cases as a competing risk.
EventMorbidity PatternCases/Person-YearsHazard Ratio (95%CI)
Breast cancer as first diagnosed cancer
No-predominant morbidity3534/1,110,9791.00 (Reference)
Psychiatric morbidities 381/115,4761.04 (0.94–1.16)
Respiratory/immunological morbidities 611/195,1290.98 (0.90–1.07)
Cardiovascular/metabolic morbidities 246/758,4230.93 (0.81–1.06)
Unspecific morbidities 554/173,9570.98 (0.89–1.07)
Non-breast cancer as first diagnosed cancer
No-predominant morbidity4964/1,110,9791.00 (Reference)
Psychiatric morbidities 485/115,4760.96 (0.88–1.06)
Respiratory/immunological morbidities 1041/195,1291.18 (1.11–1.27)
Cardiovascular/metabolic morbidities 561/758,4231.19 (1.09–1.30)
Unspecific morbidities 862/173,9571.00 (0.93–1.07)
Death
No-predominant morbidity645/1,110,9791.00 (Reference)
Psychiatric morbidities 126/115,4761.82 (1.50–2.21)
Respiratory/immunological morbidities 203/195,1291.68 (1.44–1.97)
Cardiovascular/metabolic morbidities 242/758,4233.06 (2.61–3.58)
Unspecific morbidities 205/173,9571.65 (1.41–1.94)
HR: hazard ratio; CI: confidence interval. The model was adjusted for age at baseline (continuous), age at menarche (continuous), age at menopause (still had periods; had menopause before the age of 45 years; had menopause between the age of 45 and 54; had menopause after the age of 55), menopausal hormone therapy use (never; ever, less than 5-year duration; ever, 5 years and longer; ever, unknown duration), oral contraceptive use (never; ever, less than 10-year duration; ever, at least 10-year duration; ever, unknown duration; unknown status), parity and age at first birth (no live birth; at least one birth before age 30; at least one birth after age 30), BMI (continuous), ethnicity (Asian; Black/Caribbean; White; others/unknown), Townsend score (continuous); level of physical activity (low; moderate; high), alcohol consumption (never; twice a week or less; three times a week or more; unknown status).
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Henyoh, A.M.S.; Allodji, R.S.; de Vathaire, F.; Boutron-Ruault, M.-C.; Journy, N.M.Y.; Tran, T.-V.-T. Multi-Morbidity and Risk of Breast Cancer among Women in the UK Biobank Cohort. Cancers 2023, 15, 1165. https://doi.org/10.3390/cancers15041165

AMA Style

Henyoh AMS, Allodji RS, de Vathaire F, Boutron-Ruault M-C, Journy NMY, Tran T-V-T. Multi-Morbidity and Risk of Breast Cancer among Women in the UK Biobank Cohort. Cancers. 2023; 15(4):1165. https://doi.org/10.3390/cancers15041165

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Henyoh, Afi Mawulawoe Sylvie, Rodrigue S. Allodji, Florent de Vathaire, Marie-Christine Boutron-Ruault, Neige M. Y. Journy, and Thi-Van-Trinh Tran. 2023. "Multi-Morbidity and Risk of Breast Cancer among Women in the UK Biobank Cohort" Cancers 15, no. 4: 1165. https://doi.org/10.3390/cancers15041165

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