*3.1. Demographics*

#### 3.1.1. Sample Characteristics

Of the total sample, 372 (74.5%) participants were female, 125 (25.1%) male, and two indicated "other" as their gender (0.4%). The age ranged between 18 and 76 years (*M* = 46.67, *SD* = 12.20). The majority of participants had German nationality (97%) and indicated Germany as their country of residence (99%). Participants had various levels of education, but a substantial part of the sample had higher (university) education (no degree: *n* = 5, 1.0%, Volks-/Hauptschulabschluss (primary school/secondary school): *n* = 22, 4.4%, Realschulabschluss/Mittlere Reife (secondary school leaving certificate): *n* = 118, 23.6%, Fachabitur/Fachhochschulreife (secondary school with qualification for technical university entrance): *n* = 60, 12.0%, Abitur/Allgemeine Hochschulreife (secondary school with qualification for university entrance): *n* = 80, 16.0%, university degree: *n* = 203, 40.7%, other: *n* = 10, 2.0%, one missing). Fifty-nine percent of participants reported being on disability, whereas 17% were working part-time, 12% were unemployed, 8% retired, 6% working full-time, 6% students, and 5% homemakers (multiple answers possible).

#### 3.1.2. Health-Related Demographics

Ninety percent of participants (*n* = 450) reported that they have been diagnosed with ME/CFS. All participants indicated that their problem with fatigue/energy lasted at least 6 months, with the majority of participants reporting a duration of 2 years or longer ("How long ago did your problem with fatigue/energy begin?", 6–12 months (*n* = 8, 1.6%), 1–2 years (*n* = 16, 3.2%), longer than 2 years (*n* = 377, 75.6%), had a problem with fatigue/energy since childhood or adolescence (*n* = 98, 19.6%)). In line with Salit [26], three quarters of the sample (*n* = 378) reported that their fatigue/energy-related illness started after they experienced an infectious illness.

#### *3.2. Access to and Satisfaction with Medical Care*

Results on service utilization ("Did you utilize any of these services in the past 6 months in regard to ME/CFS?", multiple answers possible) showed that participants predominantly visited their primary care physician, used ME/CFS self-help services, and alternative medicine. To a lesser extent, they visited specialized physicians, used mental health services or visited the hospital with regards to ME/CFS (Table 1).

**Table 1.** Frequencies of service utilization within the past 6 months with regards to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).


Concerning barriers to service access ("Are there any services that you would like to use but are not accessible to you for one or more of the following reasons?"), all items except "ME/CFS specialist has a full waiting list" were affirmed by more than half of participants. The main factors participants perceived as barriers to service access were geographical reasons (i.e., lack of ME/CFS specialists in the area and lack of transportation), financial or insurance reasons, as well as lack of information about services (Table 2).

The nine items measuring patient satisfaction with medical care were averaged to a scale (α = 0.92). On average, participants indicated that they were rather not satisfied with medical care by the doctor they most frequently visited due to ME/CFS (*M* = 2.36, 95% CI [2.29; 2.43], *SE* = 0.04) which was significantly below the scale midpoint of 2.5 (*t*(469) = 4.08, *SE* = 0.03, *p* < 0.001). Half of the sample (*n* = 252, 50.5%) indicated that they visited their GP most frequently due to ME/CFS, whereas 32.9% (*n* = 164) visited a specialized physician, and 16.2% (*n* = 81) indicated that they were currently not in treatment due to ME/CFS. The physicians' areas of specialty most frequently stated by patients were neurology/psychiatry, general medicine, internal medicine, hygiene and environmental medicine, as well as hematology and oncology (a detailed frequency table can be found on the OSF). Furthermore, 123 participants (24.6%) indicated that they were in treatment by a physician specialized in ME/CFS. These participants completed the satisfaction items again with regards to the specialist (α = 0.92). Results showed that satisfaction with medical care by a ME/CFS specialist was higher than the scale midpoint

(*M* = 3.16, 95% CI [3.05; 3.26], *SE* = 0.06; *t*(122) = 11.70, *p* < 0.001). Furthermore, participants in this subsample reported higher satisfaction with medical care by a ME/CFS specialist compared to care by a physician not specialized in ME/CFS ( *M* = 2.87, 95% CI [2.74; 3.00], *SE* = 0.07, *t*(121) = 4.64, *p* < 0.001).

**Table 2.** Frequencies of perceived barriers to medical care access.


ME/CFS: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

#### *3.3. German Version of the DePaul Symptom Questionnaire Short Form*

For the DSQ-SF, we created composite scores per item by averaging frequency and severity ratings and then multiplying them by 25 to create a scale ranging from 0 to 100 for ease of interpretation [30]. Table 3 displays descriptive statistics of the DSQ-SF items (frequency and severity displayed separately in their original metric ranging from 0 to 4).

**Table 3.** Descriptive statistics of German-language DePaul Symptom Questionnaire Short Form (DSQ-SF) items.


*Notes.* Results are displayed in the original metric before transformations. Frequency was assessed on a scale from 0 = none of the time to 4 = all of the time. Severity was assessed on a scale from 0 = symptom not present to 4 = very severe. Chronbach's αs indicate internal consistencies of the scale when the item is removed (complete scale before transformations: α = 0.899).

> The confirmatory factor analysis on the composite scores (Cronbach's α = 0.83) showed that the fit of a single-factor model was acceptable ( *χ<sup>2</sup>*(73) = 222.70, *p* < 0.001; RMSEA = 0.06, CFI = 0.92, TLI = 0.90, SRMR = 0.05) when correlated error terms of the following items were allowed: "bloating" and "irritable bowel problems", "problems remembering things" and "difficulty paying attention for a long period of time", "cold limbs" and "feeling hot or cold for no reason", as well as "unrefreshed sleep" and "muscle pain". Detailed results of the CFA can be found on the Open Science Framework.

> To investigate the construct validity of the German translation of the DSQ-SF, we computed bivariate correlations of the scale with the functional status (as measured by the SF-36). Higher frequency and severity of ME/CFS symptoms was significantly associated with lower functional status on all subscales. High correlations (*r* > 0.58) were found with the subscales of physical functioning and bodily pain, whereas correlations with social

functioning, general health, vitality, and mental health were moderate (0.41 > *r* > 0.25). Small correlations were found with role physical and role emotional (*r* < 0.18; Table 4).

**Table 4.** Bivariate correlations of the German-language DSQ-SF with the functional status.


*Notes.* \* *p* < 0.05, \*\* *p* < 0.01, \*\*\* *p* < 0.001. Gender was coded 0 = male, 1 = female. Displayed coefficients are Pearson correlations. Higher scores on the DSQ-SF represent more frequent/severe ME/CFS symptoms. Higher scores on the SF-36 subscales represent higher functioning.

## **4. Discussion**

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a severe and chronic illness for which currently no cure or biomarker exists. ME/CFS is associated with losses of income and economic productivity [4,16,20,38]. Based on a prevalence of 0.4% [12,13], it is estimated that 332,000 people (including 54,000 children and adolescents) in Germany are affected by ME/CFS. Evidence from the United States indicates that people with ME/CFS are medically underserved [20,24,25]. The current research shows that this is likely also the case in Germany. An online questionnaire was distributed by the four largest German ME/CFS patient organizations. The final sample consisted of 499 participants with self-reported ME/CFS who fulfilled the Canadian Consensus Criteria [32] and indicated experiencing post-exertional malaise of 14 h or longer [33]. All participants included in the final sample also fulfilled diagnostic criteria by the Institute of Medicine [4].

#### *4.1. Patients with ME/CFS in Germany Are Medically Underserved*

Results point in the direction that people with ME/CFS in Germany are severely impaired in terms of health and social, as well as economic functioning. Despite high levels of education, only less than one quarter of the sample reported working part-time or full-time, whereas more than half of the participants were on disability. This pattern shows that similar to other countries, Germany also suffers financial and economic losses due to people living with ME/CFS not being able to contribute to the labor market [12,16,20,38]. Due to the chronic nature of the illness, this is unlikely to change, as more than 95% of the sample reported having had problems with fatigue/energy for 2 years or longer.

Results on access to and satisfaction with medical care present further evidence that patients with ME/CFS are medically underserved in Germany. Most patients reported being treated by their primary care physician and only one third reported having seen a physician specialized in ME/CFS in the last 6 months. This is consistent with evidence from the United States, where the number of ME/CFS specialists was reported to be low [20,23,24]. Moreover, the majority of participants indicated using self-help and alternative medicine, but only 40% or less reported being in treatment by a neurologist or other specialized physician. This pattern might indicate that patients use alternative services in search of treatment, as they might feel that primary care and specialized physicians are not able to provide them with satisfactory medical care. This is underlined by a recent literature review and expert survey on GP knowledge and understanding of ME/CFS. Results showed that in different European countries, between one third and half of GPs did not accept ME/CFS as a genuine clinical entity and even when they did, they lacked confidence in diagnosing or managing it [39,40]. Furthermore, in line with results from Sunnquist, Nicholson, Jason, and Friedman [20] as well as Thanawala and Taylor [22], patients with ME/CFS in Germany also predominantly reported both geographical/logistic as well as financial/insurance

reasons for not being able to use medical services more frequently. This pattern reflects that the number of physicians specializing in ME/CFS in Germany is too low and as a consequence, patients are required to travel long distances to visit ME/CFS specialists, which might be prevented by or even exacerbate their ME/CFS symptoms. Insurance barriers include that the current official diagnostic guidelines on fatigue in Germany [41] recommend cognitive-behavioral therapy and graded exercise therapy as treatment. Other medical care might not be covered by health insurance. Furthermore, not being able to work and suffering associated income losses might also contribute to financial barriers to service utilization.

Findings are further corroborated by results on satisfaction with medical care. Overall, satisfaction with medical care by the physician patients visited most frequently due to ME/CFS (in most cases, the primary care physician) was reported to be low. Only one third of participants reported having seen a physician specialized in ME/CFS in the last 6 months. However, this subsample was significantly more satisfied with the medical care they received from the ME/CFS specialist compared to the non-specialist care. This is in line with studies showing that the medical personnel is not knowledgeable about ME/CFS and often attributes ME/CFS symptoms to psychological causes, which leads to patients being dissatisfied with the medical care they receive [20,24,25,39,40]. To provide patients with ME/CFS in Germany with improved medical care, we conclude that a more frequent and detailed education of medical students, physicians, and other medical personnel in Germany about ME/CFS symptoms, diagnostic criteria, and treatment approaches is necessary [39].

Research has shown a link between severe viral infection and ME/CFS [42] and 75% of the current sample reported that they developed ME/CFS after an infectious illness. In light of the current COVID-19 pandemic, it is to be expected that people recovering from SARS-CoV-2 are at risk of developing ME/CFS [43,44]. For example, a recent study from Germany showed that half of the participants with chronic COVID-19 syndrome fulfilled the Canadian Consensus Criteria for ME/CFS 6 months post infection with SARS-CoV-2 [45]. The expected increase in ME/CFS cases in Germany and around the world due to the COVID-19 pandemic creates an urgency to improve the medical care situation of patients with ME/CFS by providing better care and adequate diagnostic instruments.

#### *4.2. The German-Language DSQ-SF: A Reliable and Valid Instrument for Research and Clinical Practice*

In the absence of diagnostic tests or biomarkers for ME/CFS [27,28], the DSQ has been developed based on the Canadian Consensus Criteria [32] to assess ME/CFS symptoms. The instrument is available in several versions and has been translated into a variety of languages [30]. The DSQ has demonstrated excellent psychometric properties including high reliability and validity, as well as high sensitivity and specificity to classify patients with ME/CFS [30,31]. The current research provides a German-language translation of the brief DSQ-SF, which encompasses only 14 items and is thus well-suited for time-sensitive research protocols and clinical practice to diagnose ME/CFS [31]. The German translation of the DSQ-SF showed high reliability, the expected single-factor structure, as well as construct validity. Higher scores on the frequency and severity of ME/CFS symptoms correlated negatively with all subscales of the SF-36 [35,36], an established instrument to assess the functional status. This means that stronger ME/CFS symptoms assessed by the German version of the DSQ-SF were associated with the patients' lower functional status. The pattern of interrelations of the DSQ-SF with the subscales of the SF-36 reflects the most common symptoms of ME/CFS. The strongest correlations were found with the subscales of physical functioning and bodily pain, reflecting the hallmark symptoms of post-exertional malaise, fatigability, as well as muscle weakness and pain. Moderate correlations were found with social functioning, general health, vitality and mental health, reflecting that patients with ME/CFS are severely impaired in terms of societal and social participation (see [34] for a detailed analysis on the relation of perceived stigma due to ME/CFS and lower functional status). As an indicator of discriminant validity, only small correlations of the DSQ-SF were found with the subscales of role physical and role emotional. This result reflects that due to the chronic nature of the illness, participants might have found ways to cope with the impairment they experience due to their symptoms and the associated difficulties for social relationships. Taken together, the current research provides a novel German translation of the DSQ-SF to be used for research and clinical practice in German-speaking countries.

#### *4.3. Limitations and Future Directions*

A first limitation is that the current research investigated the medical care situation of people who responded to an online questionnaire measuring only self-reported ME/CFS. This convenience sample might not be representative for the general population of patients with ME/CFS in Germany. However, we took several measures to ensure that our sample reflects the situation of patients with ME/CFS in Germany as accurately as possible. First, the questionnaire was distributed via the four largest German patient organizations, their mailing lists, and social media, increasing the likelihood of reaching patients with ME/CFS. Second, we excluded participants who did not fulfill the Canadian Consensus Criteria and did not report post-exertional malaise of at least 14 h after exertion [32,33]. Relatedly, the educational level of the sample was very high (40% reported having a university degree). It might be possible that highly educated patients with ME/CFS were particularly able or likely to participate in the online study due to higher familiarity with online questionnaires or better technical equipment/digital literacy. A combination of online recruitment and face-to-face recruitment in hospitals/doctor offices would be ideal to avoid systematic recruitment bias. However, as data were collected during the first wave of the COVID-19 pandemic (May/June 2020), such a combined recruitment approach was not possible. Future research could include a sample with a physician-confirmed diagnosis, collect data via paper-pencil questionnaires, and compare the situation of patients with ME/CFS to that of healthy controls and/or patients with other fatigue-related illnesses (e.g., multiple sclerosis).

A second limitation is that the questionnaire study was correlational and crosssectional. Therefore, we could not investigate the medical care situation and relationships of ME/CFS symptoms with the functional status over time. Third, the current study did not include a comparison group of healthy controls or patients with other chronic illnesses to differentiate patients with ME/CFS from others. Thus, we could not investigate the Receiver Operating Characteristic analysis to set thresholds for subscores to assist with the diagnosis of ME/CFS in Germany. Future studies should include longitudinal study designs, ME/CFS screening questions in population-representative samples, studies with comparison groups, as well as cross-national surveys to shed a more encompassing light on the medical care situation of people with ME/CFS in Germany and other countries.

Finally, due to a programming error the DSQ-PEM was not fully assessed in the current research. The two items "next day soreness or fatigue after non-strenuous, everyday activities" and "minimum exercise makes you physically tired" are identical in the DSQ-SF and the DSQ-PEM, but were assessed only once in the current study. We provided the German translation for the DSQ-PEM in Appendix A, but could not investigate its psychometric properties. In our analyses, we only used one item to determine the cutoff value of >14 h of PEM duration as an inclusion criterion for our sample. Future studies should investigate the validity and reliability of the German version of the DSQ-PEM, as well as its interrelations with the DSQ-SF and functional status.

## **5. Conclusions**

Results of the current research raise concerns about the medical care situation of people with ME/CFS in Germany, showing the need for adequate education of physicians about ME/CFS, as well as a more specialized treatment of patients with ME/CFS. Furthermore, there is a need for instruments to diagnose ME/CFS to be used in research and clinical practice. The current research provides a German version of the well-established DSQ-SF

in order to provide an instrument to assess ME/CFS symptoms reliably and validly in German-speaking countries.

**Author Contributions:** Conceptualization, L.F., D.B.R.H., L.A.J., C.S. and U.B.; methodology, L.F., D.B.R.H. and L.A.J.; software, formal analysis, L.F. and M.T.; writing—original draft preparation, L.F., D.B.R.H. and M.T.; writing—review and editing, L.A.J., C.S. and U.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Weidenhammer Zöbele Foundation.

**Institutional Review Board Statement:** The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Institutional Review Board (or Ethics Committee) of FernUniversität in Hagen (number EA\_217\_2019, date of approval: 25 March 2020).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** Materials, data, and analysis scripts are available on the Open Science Framework [https://osf.io/5d8vu/ (use: 22 June 2021)].

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
