Diagnostic Technology: Trends of Use and Availability in a 10-Year Period (2011–2020) among Sixteen OECD Countries

Round 1

Reviewer 1 Report

Dear Author,

This is an interesting study that aims to assess a trend over a ten-year timeframe on imaging tests and radiology devices in 16 countries belonging to the Organisation for Economic Co-operation and Development. However, this work is already published in Popul. Med. 2023;5(Supplement): A1779 (2023-04-26) done by the same authors (Manuela Martella , Jacopo Lenzi , Maria Michela Gianino).

Accordingly, I think the policy of your Journal does not accept a work already done and published before in other journal.

 

Good luck

Moderate editing of English language required to improve the quality of English Language

Author Response

Dear Reviewer,

Thank you for your kind comment. We are glad to know you appreciated our work. As requested by the Academic Editor, we have rewritten the abstract to remove any overlapping with what is already in the conference proceedings of Population Medicine. 

Abstract.

Background. Overuse of imaging results in cost increases with little to no benefit to patients. The purpose of this study is to evaluate imaging tests and radiology equipment over a ten-year period in 16 Organisation for Economic Co-operation and Development (OECD) countries.
Methods. Twelve countries were included in a time-trend analysis based on OECD indicators on diagnostic imaging (computer tomography [CT], magnetic resonance imaging [MRI], and positron emission tomography [PET]). These annual indicators included the number of exams per 1000 population, the number of devices per million population, and the number of exams per device. Average annual percent change was used to measure country-specific trends.
Results. Most countries saw a rise in the exam-to-scanner ratio for CT, MRI, and PET, demonstrating a faster increase in exam volume than device volume. Italy exhibited an increase in CT, MRI and PET equipment units during the same period, but not in exams, most likely due to a reduction in medical procedures during the pandemic. Only in Luxemburg CT and PET examinations increased despite a reduction in scanners. Conclusion. Because there is a rise in the overuse of imaging worldwide, proper governance and resource allocation are necessary requirements for cost-efficient health systems.

 

For more details, please see the revised manuscript.

Reviewer 2 Report

Martella et al carried out an estimate of diagnostic imaging utilization trend, across a 10-year-long period, in 16 OECD countries. The study was performed by retrieving data from online database OECD Health Statistics 2022. The importance of proper health system management and the need to minimize imaging overuse is a relevant issue. In their survey, Authors clearly provide evidence that a trend towards overuse in 16 countries in the considered time-frame.

Some assertions need rephrasing, and some typo mistakes should be corrected.

 Minor comments

 ABSTRACT

 The trend exam-to-scanner ratio for CT, RMI and PET grew during the 16 study-period in most of countries.

 Change RMI to MRI

  During the same timeframe, Italy registered an increase of CT, MRI and PET units, although exams did not, likely because of the contraction of medical procedures during pandemic.

 Throughout the manuscript, Authors should better replace the word “unit” with “equipment unit” or an analogous word, since “unit” may be misleading as potentially referring to “work unit” (including setting and personnel) rather than to the “machinery unit”

 Introduction

 page 1, line 35-38

This overuse of tests, i.e., the delivery of tests with no clear benefit or when the potential harms outweigh the potential benefits, is not only a waste of finite healthcare expenditure by diverting resources from beneficial tests and treatments, but is also subjects patients to low-value care.

 Probably “……but IT also subjects patients to low-value care.”

 Materials and Methods

 Ok

 

Results, page 4, line 144

3.1.1. Computed Tomography

 As shown in Figure 1 and Table 1, the number and use of CT scans varied greatly across OECD countries…

 Throughout the paragraph, Authors should better replace “number and use of CT scans” with “CT scanners” or an equivalent term (as properly described in Table 1”, in order to improve readability.

 Discussion, line 320

Although there is no official guidance on the provision of imaging devices (RT, MRI, and PET)

Correct RT (CT)

 

 Minor revision needed. Some typo mistakes should be corrected.

Author Response

Dear Reviewer, 

Thank you for your suggestions. Please see our replies to your comments.

Response to REVIEWER #2:

Martella et al carried out an estimate of diagnostic imaging utilization trend, across a 10-year-long period, in 16 OECD countries. The study was performed by retrieving data from online database OECD Health Statistics 2022. The importance of proper health system management and the need to minimize imaging overuse is a relevant issue. In their survey, Authors clearly provide evidence that a trend towards overuse in 16 countries in the considered time-frame. Some assertions need rephrasing, and some typo mistakes should be corrected.

Response: Thank you for your kind comment. We are glad to know you appreciated our work.

 

Abstract: “The trend exam-to-scanner ratio for CT, RMI and PET grew during the 16 study-period in most of countries”. Change RMI to MRI.

Response: Thank you for noticing this inaccuracy. The text has been changed as suggested.

 

Abstract: “During the same timeframe, Italy registered an increase of CT, MRI and PET units, although exams did not, likely because of the contraction of medical procedures during pandemic”. Throughout the manuscript, Authors should better replace the word “unit” with “equipment unit” or an analogous word, since “unit” may be misleading as potentially referring to “work unit” (including setting and personnel) rather than to the “machinery unit”.

Response: Thank you for noticing this inaccuracy. We have now replaced “unit” with “equipment unit” throughout the text.

 

Introduction (page 1, line 35-38): “This overuse of tests, i.e., the delivery of tests with no clear benefit or when the potential harms outweigh the potential benefits, is not only a waste of finite healthcare expenditure by diverting resources from beneficial tests and treatments, but is also subjects patients to low-value care”. Probably “……but IT also subjects patients to low-value care.”

Response: Thank you for noticing this inaccuracy. The text has been changed as suggested.

 

Results (page 4, line 144): “As shown in Figure 1 and Table 1, the number and use of CT scans varied greatly across OECD countries…”. Throughout the paragraph, Authors should better replace “number and use of CT scans” with “CT scanners” or an equivalent term (as properly described in Table 1”, in order to improve readability.

Response: Thank you for your suggestion. We have now replaced “scan(s)” with “scanner(s)” throughout the text.

 

Discussion (line 320): “Although there is no official guidance on the provision of imaging devices (RT, MRI, and PET)”. Correct RT (CT).

Response: Thank you for noticing this inaccuracy. The text has been changed as suggested.

 

For more details, please see the revised manuscript.

Reviewer 3 Report

This manuscript examines the trends in diagnostic technology utilization and accessibility in sixteen OECD countries over a ten-year period, specifically focusing on imaging tests and radiology devices. The study analyzes the exam-to-scanner ratio for CT, MRI, and PET across different countries and explores the potential impact of excessive imaging on healthcare costs and patient outcomes. However, I have some concerns about certain aspects of the manuscript that I believe need to be addressed for it to be considered for publication:

1. Data Collection Methods: The manuscript lacks specific details regarding the data collection methods used by the OECD. It is unclear whether the collected national-level data encompassed all eligible hospitals performing imaging. Furthermore, there is no discussion about if there’s any changes in data collection methods during the ten-year period, raising questions about the comparability of data across different years.

2. Calculation and Comparison of Results: The manuscript relies on calculations from "Exams per scanner," "Exams per 1000 population," and "Scanners per million population," to compare results among different countries and imaging modalities. However, the presentation of the results and subsequent discussion lack proper organization, making it challenging to derive clear conclusions from the findings.

3. Consideration of Disease Types and Aging Population: The manuscript does not take into account the specific types of diseases for which imaging is utilized, nor does it consider the effect of changes in the aging population over the ten-year period. These factors can significantly influence the assessment of "inefficient use" and "oversupply" of imaging technology, as different diseases may have varying imaging requirements and healthcare demands may shift due to population aging.

4. Technological Advancements: The manuscript does not adequately acknowledge the significant advancements in imaging technology over the past decade. While older generations of scanners may still be available, their usage may have declined due to the increased efficacy of advanced machines. This aspect should be considered when evaluating the availability and utilization of imaging technology.

In summary, although the manuscript presents a substantial amount of data obtained from online databases, there is a need for improved organization and statistical analysis. Several key parameters that are crucial in assessing the use and availability of imaging technology have been overlooked. Consequently, I believe that further revisions are necessary for this paper to meet the publication standards.

N/A

Author Response

Dear Reviewer,

We really appreciated your suggestion and edited the manuscript as attached below.

Response to REVIEWER #3

This manuscript examines the trends in diagnostic technology utilization and accessibility in sixteen OECD countries over a ten-year period, specifically focusing on imaging tests and radiology devices. The study analyzes the exam-to-scanner ratio for CT, MRI, and PET across different countries and explores the potential impact of excessive imaging on healthcare costs and patient outcomes. However, I have some concerns about certain aspects of the manuscript that I believe need to be addressed for it to be considered for publication.

Response: Thank you for your thorough review. We hope we have addressed all the issues raised.

 

1. Data Collection Methods: The manuscript lacks specific details regarding the data collection methods used by the OECD. It is unclear whether the collected national-level data encompassed all eligible hospitals performing imaging. Furthermore, there is no discussion about if there’s any changes in data collection methods during the ten-year period, raising questions about the comparability of data across different years.

Response: Thank you for your comment. As stated on lines 91–94, the annual number of exams and scanners covers “both hospitals and ambulatory care providers”, which means that all hospitals performing imaging are monitored and counted in the OECD indicators. To make this clear, we have now stated that these indicators include exams and equipment “in ALL hospitals and ambulatory care providers”. However, some deviations from international definitions and other methodological issues are present and have been described as footnotes to charts and tables, as already stated at the very end of the Materials and Methods section (lines 143–145). Lastly, we have provided on lines 97–104 the links to OECD official documentation about specific definitions, sources and methods for all indicators, overall and for each member country.

 

2. Calculation and Comparison of Results: The manuscript relies on calculations from "Exams per scanner," "Exams per 1000 population," and "Scanners per million population," to compare results among different countries and imaging modalities. However, the presentation of the results and subsequent discussion lack proper organization, making it challenging to derive clear conclusions from the findings.

Response: Thank you for your comment. We think that, in their present form, subsections 3.1.1–3.1.3 are organized consistently e follow the same structure: (i) between-country variability; (ii) minimum and maximum number of exams and scanners in 2020 or last available year; (iii) countries with no significant trend in exams and scanners; (iv) countries with a significant increase in exams only; (v) countries with a significant increase in scanners only; (vi) countries with conflicting significant trends (i.e., exam increase vs. scanner decrease or vice versa); (vii) countries with a significant increase in both exams and scanners; (viii) among these countries (the majority), which one register a significant increase or decrease in exam-to-scanner-ratios; (ix) sensitivity analysis. For this reason, we would keep the Results section as it is; however, to make it clear that the text follows a clear pattern, we have now split each subsection (§§ 3.1.1–3.1.3) into four paragraphs.

3. Consideration of Disease Types and Aging Population: The manuscript does not take into account the specific types of diseases for which imaging is utilized, nor does it consider the effect of changes in the aging population over the ten-year period. These factors can significantly influence the assessment of "inefficient use" and "oversupply" of imaging technology, as different diseases may have varying imaging requirements and healthcare demands may shift due to population aging.
4. Technological Advancements: The manuscript does not adequately acknowledge the significant advancements in imaging technology over the past decade. While older generations of scanners may still be available, their usage may have declined due to the increased efficacy of advanced machines. This aspect should be considered when evaluating the availability and utilization of imaging technology.

Response: Dear reviewer, we really appreciated your suggestion. We modified our discussion as follows:

4. Discussion

This study evaluates the trends of exams/diagnostic technologies ratio, through the analysis of the trend in the number of examinations per population and the number of CT or PET scanners or MRI equipment units per population in the 2011-2020 period for 16 OECD countries.

Four distinct Behaviours  can be identified:

1. The ratio of exams to diagnostic technologies decreases with an increase in the number of diagnostic technologies per population and a reduction in the number of examinations per population;
2. The ratio decreases with a greater increase in diagnostic technologies per population compared to an increase in the number of examinations per population;
3. The ratio increases due to a smaller increase in diagnostic technologies per population compared to an increase in the number of examinations per population;
4. The ratio increases with a reduction of diagnostic technologies by population and an increase in the number of examinations per population.

Behaviours 1 and 2 seem to show an excess of supply, which results in an in-efficient use of diagnostic technologies. Behaviour 4, which has a reduced supply, suggests a better exploitation of the production capacity of diagnostic technologies. Finally, Behaviour 3 is difficult to interpret. Indeed, not having a benchmark for the ideal number of exams per equipment unit of diagnostic technologies makes it difficult to make a judgment on the actual need to increase the number of diagnostic technologies or whether it would be sufficient to optimize the use of existing technologies. Behaviours 1 and 2, which show a more rapid stockpiling of devices, may be affected by multiple factors.  A likely factor may lie in significant advancements in imaging technology. While older generations of scanners may still be available, their usage may have declined due to the increased efficacy of advanced machines. The extent to which new equipment substitutes for other technologies and the lack decommissioning of older diagnostic technology devices can lead to over-supply.

Another possible cause may be associated with disputable evaluation of financial investments that, correctly, should incorporate both the benefits and costs of new technologies. In this regard, although there is no official guidance on the provision of imaging devices (CT, MRI, and PET), setting priorities and recommendations for such technologies would be a step towards achieving operational efficiency, which is about meeting objectives at least cost and allocative efficiency and maximizing benefits with the resources available. Such recommendations seek to ensure that healthcare resources are fairly allocated (18). In this respect, to successfully implement priority setting, recently, the International Network of Agencies for Health Technology Assessment (INAHTA) launched a list of top ten challenges, including a few warnings about shifting political Behaviour, to encourage a prompt translation of HTA fundamentals into policy (19). To support the validity of this position, this study shows a virtuous example in Luxembourg where a reduction in PET and CT equipment units was possible despite the increasing demand for radiology examinations. It is reasonable to assume the adopted assessment and regulation of medical equipment as an explanation for this gain in efficiency. Be-cause it is the prerogative of the Ministry of Health and Permanent Hospital Commission promote HTA strategies for planning and managing with a politically centralized approach, the Luxembourgian Government fostered a cost-effective HTA plan in collaboration with health insurance agencies (20).

The analysis of the trend of the demand for diagnostic tests and of the trend of the offer of diagnostic technologies shows they do not always have the same slope or direction. This interesting result raises questions about the ability of supply to condition the demand for diagnostic services. For example, in the case of Behaviour 2, where there is an increase in diagnostic technologies that exceeds the demand for diagnostic tests, it would seem that supply does not have a great influence on demand. In Behaviour 1, demand seems to decline with an increase in supply, and in Behaviour 4, demand increases with a decrease in supply. Certainly, more targeted research to investigate the elasticity of demand with respect to supply is needed. Additionally, since demand in this study is measured as the number of diagnostic tests performed, it is possible that there is still an influence of supply on the demand for diagnostic tests not still performed, resulting in a waiting list.  Moreover, it is certainly possible that part of the diagnostic tests delivered is already the result of overutilization or inappropriate utilization conditioned by the supply. However, the different slopes or directions in the trends suggest the role of other significant factors in determining the demand for diagnostic exams. For instance, demographic and epidemiological variations over the decades could have notably impacted the level of assistance required, including diagnostics, and could have required varying imaging requirements.

A secondary but not less relevant the study’s result showed that until 2019, the pre-COVID-19 period, all countries recorded an increase in the number of exams per 1,000 population. Only Italy saw a reduction in the number of MRI exams. Various factors contributed to this, such as advances in imaging technology, aging populations, epidemiological transition leading many older patients with more comorbidities requiring diagnosis availability of technology, healthcare system characteristics, such as the payment system. Also work organization and availability of doctors and other health workers in a sufficient number can have affected number of exams. Indeed, it is plausible that insufficient recruitment of new per-sonnel may have further exacerbated the workload of radiologists that are already burdened by excess number of patients per scanner and so that can perform less efficient diagnosis many times thus requiring further diagnoses. Additionally, specialists’ behaviour and education can also have driven the prescription of radiology exams. Studies have highlighted that reassuring patients is a leading reason for prescription, exceeding even defensive medicine (21,22,23).Lastly, the social context may have driven the culture of overuse regarding health and healthcare issues. This suggestion gains some support by critical perspective from Canada, under which the increasing demand for diagnostic tests seems to be the consequence of a multifaceted context that shapes the health beliefs, values, and behaviours of both patients and providers (24)

In this field, the “patient-centered care” is a novel reform in the US that aims to engage patients in managing their own health and forge partnerships with their clinicians by obtaining real-time access to their own medical records and science-based comparative effectiveness information for a better personalization of medical care. In this context, the Choosing Wisely campaign was fostered by medical specialty societies, the American Board of Internal Medicine (ABIM) Foundation, and Consumer Reports (a nonprofit consumer organization), by selecting and listing five tests, treatments, or services to reconsider clinical usefulness and validity from both patients’ and clinicians’ points of view (25).

In conclusion, studies on the determinants of inefficient use and oversupply of imaging technologies are currently lacking. Hence, future analysis should focus on understanding the oversupply of devices without any evident and appropriate growth of demand or the underutilization of currently available radiology devices. Both professionals and policy-makers must be involved in the application of HTA strategies to manage the appropriate allocation of economic, personnel, and technology resources. Managers must be involved in the more efficient use of technologies. These issues are particularly relevant because the aging population strongly affects economic, social, and healthcare systems by modifying health needs in terms of integrated person-centered care and long-term care. In recent decades, the proportion of people older than 65 years has significantly increased (from less than 9% in 1960), and forecasts predict that this trend will continue. Indeed, projections highlight a growth from 17.3% in 2019 to 26.7% by 2050 across OECD countries, with even a few countries expected to see over one-third their population aged 65 and older and an acute increase in the number of people aged 80 and over. In Italy, this trend is even worse, where the population aged 65 will exceed one-third by 2050 and one in eight people will be 80 years old and over. Exceptional longevity of the population will likely lead to exceptional levels of both acute and chronic morbidities, requiring exceptional intensity of health assistance. Similarly, chronic diseases will challenge the traditional social welfare state and resource management. Cancer is showing improved survival rates in countries with high social settings (9,26,27). The implications of this include the need to assess emerging novel health needs such as greater demand for medical examinations and prescriptions. The main weakness of this study is that the analysis was conducted at the national level, and the statewide distribution was not analysed. An analysis carried out within the national context may highlight an uneven distribution of diagnostic technologies that could represent an excess of supply in certain geographical areas or lack of instrumentation in others, which may result in barrier to optimal utilization. Recently, a German study revealed a strong variation in imaging demand and use of PET and CT imaging units, partly due to regional variations in disease burden and supply factors primarily in ambulatory settings (28).

Similarly, the aggregated data for countries inevitably conceal large variations in terms of sociodemographic and epidemiological variables or other factors, such as the number of radiologists, which are able to play a role in the use of diagnostic technologies or in the efficiency of use of diagnostic technologies. A pilot study about the presence of radiologists and the implementation of PET-CT imaging stewardship resulted in a reduced volume of examinations due to monitoring low-value indications and appropriateness of imaging requests from clinicians through radiology consultation. (29). In addition, our analysis was performed at the country level, and countries with different financial and organizational factors of healthcare systems were both considered. Several previous studies have observed that the healthcare system or insurance system may affect the use or overuse of diagnostic exams (30, 31).

 

In summary, although the manuscript presents a substantial amount of data obtained from online databases, there is a need for improved organization and statistical analysis. Several key parameters that are crucial in assessing the use and availability of imaging technology have been overlooked. Consequently, I believe that further revisions are necessary for this paper to meet the publication standards.

Response: Thank you for your comprehensive point of view. We modified our discussion as suggested and we hope to have met the objective.

 

For more details, please see the revised manuscript.

Reviewer 4 Report

Martella et al. summarized data from real world on use of non invasive medical imaging to study how the usage of medical imaging has been over used thus putting pressure on economics. Overall presentation of the work is fine but I find it difficult to understand how imaging more patients overall or imaging less patients per scanner is putting pressure on economics. The reasons fro my concerns are 

(1) Health care professionals and radiologists are already burdened by excess number of patients per scanner and so that leads to less efficient diagnosis many times thus requiring further diagnoses or wrong diagnosis

(2) Scientists worldwide are calling for more scanners and routine scanning of more people especially older and middle-aged people to check for diseases such as breast tumor, skin cancer etc which sometimes develop symptoms in later stages. 

Apart from the above two concerns, I would advise the authors to concise the tables in the manuscript. It is difficult to read such big tables. Moreover, the figures need to be drawn more professionally and clear. Maybe put the most important results in the main manuscript and the rest in SI

None

Author Response

Dear Reviewer, 

Thank you for your kind suggestion.

Attached you can find our replies to your point and the revision of the discussion.

Response to REVIEWER #4

Martella et al. summarized data from real world on use of non invasive medical imaging to study how the usage of medical imaging has been over used thus putting pressure on economics. Overall presentation of the work is fine but I find it difficult to understand how imaging more patients overall or imaging less patients per scanner is putting pressure on economics. The reasons for my concerns are listed below.

Response: Thank you for your thorough review. We hope we have addressed all the issues raised.

 

(1) Health care professionals and radiologists are already burdened by excess number of patients per scanner and so that leads to less efficient diagnosis many times thus requiring further diagnoses or wrong diagnosis.

(2) Scientists worldwide are calling for more scanners and routine scanning of more people especially older and middle-aged people to check for diseases such as breast tumor, skin cancer etc which sometimes develop symptoms in later stages. 

Response to (1) and (2): Thank you for your suggestions; we appreciated your comments and enriched our discussion with further considerations. Hereafter the edited discussion:

Discussion

This study evaluates the trends of exams/diagnostic technologies ratio, through the analysis of the trend in the number of examinations per population and the number of CT or PET scanners or MRI equipment units per population in the 2011-2020 period for 16 OECD countries.

Four distinct Behaviours  can be identified:

1. The ratio of exams to diagnostic technologies decreases with an increase in the number of diagnostic technologies per population and a reduction in the number of examinations per population;
2. The ratio decreases with a greater increase in diagnostic technologies per population compared to an increase in the number of examinations per population;
3. The ratio increases due to a smaller increase in diagnostic technologies per population compared to an increase in the number of examinations per population;
4. The ratio increases with a reduction of diagnostic technologies by population and an increase in the number of examinations per population.

Behaviours 1 and 2 seem to show an excess of supply, which results in an in-efficient use of diagnostic technologies. Behaviour 4, which has a reduced supply, suggests a better exploitation of the production capacity of diagnostic technologies. Finally, Behaviour 3 is difficult to interpret. Indeed, not having a benchmark for the ideal number of exams per equipment unit of diagnostic technologies makes it difficult to make a judgment on the actual need to increase the number of diagnostic technologies or whether it would be sufficient to optimize the use of existing technologies. Behaviours 1 and 2, which show a more rapid stockpiling of devices, may be affected by multiple factors.  A likely factor may lie in significant advancements in imaging technology. While older generations of scanners may still be available, their usage may have declined due to the increased efficacy of advanced machines. The extent to which new equipment substitutes for other technologies and the lack decommissioning of older diagnostic technology devices can lead to over-supply.

Another possible cause may be associated with disputable evaluation of financial investments that, correctly, should incorporate both the benefits and costs of new technologies. In this regard, although there is no official guidance on the provision of imaging devices (CT, MRI, and PET), setting priorities and recommendations for such technologies would be a step towards achieving operational efficiency, which is about meeting objectives at least cost and allocative efficiency and maximizing benefits with the resources available. Such recommendations seek to ensure that healthcare resources are fairly allocated (18). In this respect, to successfully implement priority setting, recently, the International Network of Agencies for Health Technology Assessment (INAHTA) launched a list of top ten challenges, including a few warnings about shifting political Behaviour, to encourage a prompt translation of HTA fundamentals into policy (19). To support the validity of this position, this study shows a virtuous example in Luxembourg where a reduction in PET and CT equipment units was possible despite the increasing demand for radiology examinations. It is reasonable to assume the adopted assessment and regulation of medical equipment as an explanation for this gain in efficiency. Be-cause it is the prerogative of the Ministry of Health and Permanent Hospital Commission promote HTA strategies for planning and managing with a politically centralized approach, the Luxembourgian Government fostered a cost-effective HTA plan in collaboration with health insurance agencies (20).

The analysis of the trend of the demand for diagnostic tests and of the trend of the offer of diagnostic technologies shows they do not always have the same slope or direction. This interesting result raises questions about the ability of supply to condition the demand for diagnostic services. For example, in the case of Behaviour 2, where there is an increase in diagnostic technologies that exceeds the demand for diagnostic tests, it would seem that supply does not have a great influence on demand. In Behaviour 1, demand seems to decline with an increase in supply, and in Behaviour 4, demand increases with a decrease in supply. Certainly, more targeted research to investigate the elasticity of demand with respect to supply is needed. Additionally, since demand in this study is measured as the number of diagnostic tests performed, it is possible that there is still an influence of supply on the demand for diagnostic tests not still performed, resulting in a waiting list.  Moreover, it is certainly possible that part of the diagnostic tests delivered is already the result of overutilization or inappropriate utilization conditioned by the supply. However, the different slopes or directions in the trends suggest the role of other significant factors in determining the demand for diagnostic exams. For instance, demographic and epidemiological variations over the decades could have notably impacted the level of assistance required, including diagnostics, and could have required varying imaging requirements.

A secondary but not less relevant the study’s result showed that until 2019, the pre-COVID-19 period, all countries recorded an increase in the number of exams per 1,000 population. Only Italy saw a reduction in the number of MRI exams. Various factors contributed to this, such as advances in imaging technology, aging populations, epidemiological transition leading many older patients with more comorbidities requiring diagnosis availability of technology, healthcare system characteristics, such as the payment system. Also work organization and availability of doctors and other health workers in a sufficient number can have affected number of exams. Indeed, it is plausible that insufficient recruitment of new per-sonnel may have further exacerbated the workload of radiologists that are already burdened by excess number of patients per scanner and so that can perform less efficient diagnosis many times thus requiring further diagnoses. Additionally, specialists’ behaviour and education can also have driven the prescription of radiology exams. Studies have highlighted that reassuring patients is a leading reason for prescription, exceeding even defensive medicine (21,22,23).Lastly, the social context may have driven the culture of overuse regarding health and healthcare issues. This suggestion gains some support by critical perspective from Canada, under which the increasing demand for diagnostic tests seems to be the consequence of a multifaceted context that shapes the health beliefs, values, and behaviours of both patients and providers (24)

In this field, the “patient-centered care” is a novel reform in the US that aims to engage patients in managing their own health and forge partnerships with their clinicians by obtaining real-time access to their own medical records and science-based comparative effectiveness information for a better personalization of medical care. In this context, the Choosing Wisely campaign was fostered by medical specialty societies, the American Board of Internal Medicine (ABIM) Foundation, and Consumer Reports (a nonprofit consumer organization), by selecting and listing five tests, treatments, or services to reconsider clinical usefulness and validity from both patients’ and clinicians’ points of view (25).

In conclusion, studies on the determinants of inefficient use and oversupply of imaging technologies are currently lacking. Hence, future analysis should focus on understanding the oversupply of devices without any evident and appropriate growth of demand or the underutilization of currently available radiology devices. Both professionals and policy-makers must be involved in the application of HTA strategies to manage the appropriate allocation of economic, personnel, and technology resources. Managers must be involved in the more efficient use of technologies. These issues are particularly relevant because the aging population strongly affects economic, social, and healthcare systems by modifying health needs in terms of integrated person-centered care and long-term care. In recent decades, the proportion of people older than 65 years has significantly increased (from less than 9% in 1960), and forecasts predict that this trend will continue. Indeed, projections highlight a growth from 17.3% in 2019 to 26.7% by 2050 across OECD countries, with even a few countries expected to see over one-third their population aged 65 and older and an acute increase in the number of people aged 80 and over. In Italy, this trend is even worse, where the population aged 65 will exceed one-third by 2050 and one in eight people will be 80 years old and over. Exceptional longevity of the population will likely lead to exceptional levels of both acute and chronic morbidities, requiring exceptional intensity of health assistance. Similarly, chronic diseases will challenge the traditional social welfare state and resource management. Cancer is showing improved survival rates in countries with high social settings (9,26,27). The implications of this include the need to assess emerging novel health needs such as greater demand for medical examinations and prescriptions. The main weakness of this study is that the analysis was conducted at the national level, and the statewide distribution was not analysed. An analysis carried out within the national context may highlight an uneven distribution of diagnostic technologies that could represent an excess of supply in certain geographical areas or lack of instrumentation in others, which may result in barrier to optimal utilization. Recently, a German study revealed a strong variation in imaging demand and use of PET and CT imaging units, partly due to regional variations in disease burden and supply factors primarily in ambulatory settings (28).

Similarly, the aggregated data for countries inevitably conceal large variations in terms of sociodemographic and epidemiological variables or other factors, such as the number of radiologists, which are able to play a role in the use of diagnostic technologies or in the efficiency of use of diagnostic technologies. A pilot study about the presence of radiologists and the implementation of PET-CT imaging stewardship resulted in a reduced volume of examinations due to monitoring low-value indications and appropriateness of imaging requests from clinicians through radiology consultation. (29). In addition, our analysis was performed at the country level, and countries with different financial and organizational factors of healthcare systems were both considered. Several previous studies have observed that the healthcare system or insurance system may affect the use or overuse of diagnostic exams (30, 31).

 

Apart from the above two concerns, I would advise the authors to concise the tables in the manuscript. It is difficult to read such big tables. Moreover, the figures need to be drawn more professionally and clear. Maybe put the most important results in the main manuscript and the rest in SI

Response: Thank you for your suggestion. Tables 1–3 have been lightened by keeping only the first and last available years, since data points between 2012 and 2019 are already included in the supplements. Figures 1–3 have been redrawn by eliminating background colors, updating line colors to provide a colorblind-friendly palette, and by thinning line width to make data points more visible. We acknowledge that some panel are difficult to read (e.g., Finland in Figure 1), but priority was given to providing consistent axis range in order to make all countries comparable with each other. Also, because the interpretation of the exam-to-scanner ratio is strongly dependent on the other two rates, we would rather keep all the three indicators in a single graph.

 

For more details, please see the revised manuscript.

Round 2

Reviewer 1 Report

Dear Author,

The manuscript submitted for reviewed revealed a remarkable scientific work. The author in the current work is trying to assess a trend over a ten-year timeframe on imaging tests and radiology devices in 16 countries belonging to the Organisation for Economic Co-operation and Development. The author applied in his study A time-trend analysis based on OECD indicators on diagnostic imaging involved 12 European countries and four overseas countries.

However, some comments and recommendations which, when appropriately addressed, may enhance the quality of the paper.

First: What are the inclusion and exclusion criteria for that study?

Second: Author did not show the overall estimation prevalence of low-value diagnostic over testing?

Third: The author needs to distinguish primary from secondary care practices in different countries.

Fourth: Regarding quality assessment, what are the appropriate measures that taken to avoid the risk of bias?

Fifth: The Author didn’t define all outcomes for which data were sought.

Sixth: Analysis of figures should be performed in a proper and clear way and discussed well in relation to recent publications.

Seventh: There are some linguistic and grammatical errors that must be rephrased and written in a correct style.

 

Best regards 

 

 

 

 

 

There are some linguistic and grammatical errors that must be rephrased and written in a correct style

Author Response

Dear Reviewer,

Reviewer 1

First: What are the inclusion and exclusion criteria for that study?

Response: Dear reviewer, we appreciate your request about more details on inclusion and exclusion criteria. Data were collected from the OECD Health Statistics 2022 database from the section of Healthcare resources – Medical technologies.

Hereafter, you can see that we enriched the description of how and why we obtained and selected the data for our analysis:

This time-trend analysis was conducted using secondary data on diagnostic exams and medical technology from the online database OECD Health Statistics 2022 (https://stats.oecd.org/) during the ten-year period from 2011 to 2020. Data from before 2011 and after 2020 were discarded because of high proportions of missing values. In particular, the analysis was conducted on data referring to CT, MRI and PET. The choice to focus on CT, MRI, and PET technologies was based on their widespread availability in healthcare facilities and their utility in diagnosing a broad range of pathologies, both for complicated and uncomplicated clinical conditions. Moreover, the OECD dataset only provides data on healthcare utilization, specifically for CT, MRI, and PET exams. (Line 98-107)

In the OECD database, single-photon emission computed tomography is not counted among CT scanners. (Line 114-115)

Countries with more than three years of missing data for CT, MRI, or PET use over the study period were discarded, leaving 16 OECD members for analysis: 12 European countries (Belgium, Czechia, Finland, France, Greece, Italy, Lithuania, Luxembourg, the Netherlands, Poland, Slovakia, Spain) and four non-European countries (United States, Israel, South Korea, Australia). CT data for Belgium before 2013 corresponded to the number of hospitals with scanners rather than the actual number of scanners and thus were removed from the analysis. No imputation of missing country-years was performed. Hence, only complete yearly data from each country contributed to the analysis. Hence, only complete yearly data from each country contributed to the analysis. (Line 180-188)

 

Second: Author did not show the overall estimation prevalence of low-value diagnostic over testing?

Response: Dear reviewer, thank you for your suggestion.

Nevertheless, the current research does not aim to estimate the low-value nor of the diagnostic overtesting neither of the over-imaging, since our analysis does not consider proper data for the assessment of such issue. However, a preliminary background had been described as follows:

The OECD reported that 10-34% of health service spending is potentially inappropriate, and thus is considered ineffective and a waste of healthcare resources. Worldwide, it is estimated that inappropriate or low-value imaging account for 20-50% of radiological examinations. (Line 38-40)

 

Third: The author needs to distinguish primary from secondary care practices in different countries.

Response: Dear reviewer, thank you for your suggestion.

Although it was already explicated in the Materials and Methods section, we revised the manuscript for a clearer explanation.

The OECD indicators cover all exams and equipment units in hospitals and ambulatory care settings. Data stratified by setting (hospitals versus ambulatory care providers) were not analyzed due to the large number of missing values and inconsistencies in data collection and reporting across countries. (Line 176-179)

 

Fourth: Regarding quality assessment, what are the appropriate measures that taken to avoid the risk of bias?

Response: Dear reviewer, thank you for your question.

The quality assessment is not the objective of the current research. However, in relation to the risk of information bias due to inconsistencies in data reporting across countries, we have now stated at the very end of the Material and Methods section that no pooled estimate of the study indicators was performed by means of hierarchical regression analysis.

The presence of such inconsistencies across country-years is the reason why no pooled estimates of exams per scanner were calculated by means of hierarchical regression modelling. (Line 307-309)

 

Fifth: The Author didn’t define all outcomes for which data were sought.

Response: Dear reviewer, thank you for your suggestion. We revised the manuscript by distinguishing the primary outcome (exam-to-scanner ratio) from the secondary outcomes (exam and scanner rates).

The current study aims to study the evolution in the annual number of di-agnostic exams per equipment unit from 2011 to 2020 (ten years) in 16 OECD countries. In order to understand the reasons for country-specific trends in ex-am-to-scanner ratios, the annual number of exams per 1,000 population and the annual number of scanners per million population are also analyzed. (Line 92-96 )

Indicator (c) is the primary outcome of the study, while indicators (a) and (b) are secondary outcomes that constitute indicator (c) and help its interpretation. (Line 166-167)

 

Sixth: Analysis of figures should be performed in a proper and clear way and discussed well in relation to recent publications.

Response: Dear reviewer, thank you for your suggestion about the figures. To our knowledge, recent analysis of trends based on AAPC computation using OECD indicators have been not yet published; hence, it seems arduous to compare our results with previous research.

Nevertheless, we edited the manuscript to improve the presentation of our results (§ 3). Specifically, we clearly stated what is presented in tables and charts, and gave more prominence to the AAPC of exam-toscanner ratios, i.e., the primary outcome indicator of our study.

 

Seventh: There are some linguistic and grammatical errors that must be rephrased and written in a correct style.

Response: Dear reviewer, we appreciated your comments. We revised the entire manuscript improving the writing style, as suggested, with the help of a native English-speaker.

For more details, please see the revised manuscript.

Reviewer 3 Report

N/A

N/A

Author Response

Dear reviewer, thank you for your suggestions. 
Since no comments were provided, it was challenging to respond accurately to the specific points raised. 
However, we have considered the need for a revised version of the manuscript by rearranging each section 
accordingly.