Pub Date : 2025-09-21eCollection Date: 2025-01-01DOI: 10.1136/bmjmed-2025-001623
Trisha Greenhalgh
Case study is a widely used but poorly understood research method, conducted differently in different disciplines. This paper explores philosophical, theoretical and methodological issues in case study research and outlines how to conduct one. It offers preliminary guidance for policy makers on how to select and use case studies for learning and decision making. In social science research, a case study is a detailed, contextualised account of a clearly delineated, real world phenomenon, prepared prospectively using mostly qualitative methods. Social science case studies can be of various kinds (eg, theoretical or naturalistic, single or multiple, typical or extreme). A public health case study is a historical account of a health threat and how it was managed. An implementation science case study evaluates the implementation of an intervention (usually retrospectively), combining quantitative assessment against predefined objectives with a narrative of how the project unfolded. Educational case studies present real world topics as stories illustrated by data and prompt students to discuss these from different angles. Impact case studies summarise the societal impact of a research programme. Many accounts described as case studies are overly brief and superficial. The paper concludes with a call to improve the quality and consistency (and hence the usefulness) of case studies.
{"title":"Case studies: a guide for researchers, educators, and implementers.","authors":"Trisha Greenhalgh","doi":"10.1136/bmjmed-2025-001623","DOIUrl":"10.1136/bmjmed-2025-001623","url":null,"abstract":"<p><p>Case study is a widely used but poorly understood research method, conducted differently in different disciplines. This paper explores philosophical, theoretical and methodological issues in case study research and outlines how to conduct one. It offers preliminary guidance for policy makers on how to select and use case studies for learning and decision making. In social science research, a case study is a detailed, contextualised account of a clearly delineated, real world phenomenon, prepared prospectively using mostly qualitative methods. Social science case studies can be of various kinds (eg, theoretical or naturalistic, single or multiple, typical or extreme). A public health case study is a historical account of a health threat and how it was managed. An implementation science case study evaluates the implementation of an intervention (usually retrospectively), combining quantitative assessment against predefined objectives with a narrative of how the project unfolded. Educational case studies present real world topics as stories illustrated by data and prompt students to discuss these from different angles. Impact case studies summarise the societal impact of a research programme. Many accounts described as case studies are overly brief and superficial. The paper concludes with a call to improve the quality and consistency (and hence the usefulness) of case studies.</p>","PeriodicalId":72433,"journal":{"name":"BMJ medicine","volume":"4 1","pages":"e001623"},"PeriodicalIF":10.0,"publicationDate":"2025-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12458855/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145151963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-21eCollection Date: 2025-01-01DOI: 10.1136/bmjmed-2025-001986
Penelope Hawe
{"title":"The critical importance of design decisions in case studies.","authors":"Penelope Hawe","doi":"10.1136/bmjmed-2025-001986","DOIUrl":"10.1136/bmjmed-2025-001986","url":null,"abstract":"","PeriodicalId":72433,"journal":{"name":"BMJ medicine","volume":"4 1","pages":"e001986"},"PeriodicalIF":10.0,"publicationDate":"2025-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12458779/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145151991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-16eCollection Date: 2025-01-01DOI: 10.1136/bmjmed-2024-000954
Victor Sartorius, Héloïse Torchin, Luc Gaulard, Marianne Philibert, Victoria Butler, Monica Saucedo, Catherine Deneux-Tharaux, Jeanne Fresson, Jennifer Zeitlin
Abstract:
Objective: To investigate the magnitude and evolution of inequalities in neonatal mortality rates by using area based socioeconomic indices in France.
Design: National population based study.
Setting: For 2015-20, data from the French National Health Data System (Système National des Données de Santé, SNDS). For 2001-08, neonatal death certificates and aggregate vital statistics data by municipality of residence.
Participants: Live births with a gestational age ≥22 completed weeks to a mother residing in metropolitan France, 2015-20 (4 293 403 live births and 10 869 neonatal deaths), compared with a 2001-08 study (6 202 918 live births and 14 851 neonatal deaths).
Main outcome measures: Differences in neonatal mortality rate (death before day 28 of life) according to the socioeconomic characteristics of the mother's municipality of residence. Comparison with data from a 2001-08 study to assess changes in socioeconomic inequalities and their contribution to the increase in neonatal mortality rate.
Results: The neonatal mortality rate was 2.53 per 1000 live births in 2015-20. Five indicators, previously associated with perinatal mortality, were combined into a perinatal French deprivation index (P-FDep) for the main analysis. P-FDep was categorised into five equal groups (deprivation groups 1-5) for comparison with other research and into 10 equal groups (deprivation groups 1-10) for more granular analyses, with group 1 being the least and group 5 (or group 10) the most deprived group. The rate in the most deprived compared with the least deprived group for P-FDep was 1.71 (95% confidence interval 1.60 to 1.83) times higher, based on the analysis of deprivation groups 1-5. A mortality gradient existed across the groups, translating into 2496 excess deaths (23.3%) when the rate in the least deprived group was applied to all areas. The gradient was more marked when deprivation groups 1-10 were used (relative risk 1.88, 95% CI 1.71 to 2.07 for the highest to the lowest deprived group). Compared with 2001-08 (neonatal mortality rate 2.39 per 1000), the rate remained constant in the least deprived areas, but worsened in the most deprived areas (+10.1% and +11.7% for groups 4 and 5, respectively), increasing the relative risks between the highest and lowest groups, which were 1.54 (95% CI 1.46 to 1.62) for deprivation groups 1-5 and 1.67 (1.55 to 1.79) for deprivation groups 1-10, in 2001-08.
Conclusions: In this study, the socioeconomic level of the mother's place of residence was strongly associated with the neonatal mortality rate. The data showed that inequalities have widened, contributing to the increase in the neonatal mortality rate.
{"title":"Evaluation of area based socioeconomic inequalities and neonatal mortality rates in France: national population based study.","authors":"Victor Sartorius, Héloïse Torchin, Luc Gaulard, Marianne Philibert, Victoria Butler, Monica Saucedo, Catherine Deneux-Tharaux, Jeanne Fresson, Jennifer Zeitlin","doi":"10.1136/bmjmed-2024-000954","DOIUrl":"10.1136/bmjmed-2024-000954","url":null,"abstract":"<p><strong>Abstract: </strong></p><p><strong>Objective: </strong>To investigate the magnitude and evolution of inequalities in neonatal mortality rates by using area based socioeconomic indices in France.</p><p><strong>Design: </strong>National population based study.</p><p><strong>Setting: </strong>For 2015-20, data from the French National Health Data System (Système National des Données de Santé, SNDS). For 2001-08, neonatal death certificates and aggregate vital statistics data by municipality of residence.</p><p><strong>Participants: </strong>Live births with a gestational age ≥22 completed weeks to a mother residing in metropolitan France, 2015-20 (4 293 403 live births and 10 869 neonatal deaths), compared with a 2001-08 study (6 202 918 live births and 14 851 neonatal deaths).</p><p><strong>Main outcome measures: </strong>Differences in neonatal mortality rate (death before day 28 of life) according to the socioeconomic characteristics of the mother's municipality of residence. Comparison with data from a 2001-08 study to assess changes in socioeconomic inequalities and their contribution to the increase in neonatal mortality rate.</p><p><strong>Results: </strong>The neonatal mortality rate was 2.53 per 1000 live births in 2015-20. Five indicators, previously associated with perinatal mortality, were combined into a perinatal French deprivation index (P-FDep) for the main analysis. P-FDep was categorised into five equal groups (deprivation groups 1-5) for comparison with other research and into 10 equal groups (deprivation groups 1-10) for more granular analyses, with group 1 being the least and group 5 (or group 10) the most deprived group. The rate in the most deprived compared with the least deprived group for P-FDep was 1.71 (95% confidence interval 1.60 to 1.83) times higher, based on the analysis of deprivation groups 1-5. A mortality gradient existed across the groups, translating into 2496 excess deaths (23.3%) when the rate in the least deprived group was applied to all areas. The gradient was more marked when deprivation groups 1-10 were used (relative risk 1.88, 95% CI 1.71 to 2.07 for the highest to the lowest deprived group). Compared with 2001-08 (neonatal mortality rate 2.39 per 1000), the rate remained constant in the least deprived areas, but worsened in the most deprived areas (+10.1% and +11.7% for groups 4 and 5, respectively), increasing the relative risks between the highest and lowest groups, which were 1.54 (95% CI 1.46 to 1.62) for deprivation groups 1-5 and 1.67 (1.55 to 1.79) for deprivation groups 1-10, in 2001-08.</p><p><strong>Conclusions: </strong>In this study, the socioeconomic level of the mother's place of residence was strongly associated with the neonatal mortality rate. The data showed that inequalities have widened, contributing to the increase in the neonatal mortality rate.</p>","PeriodicalId":72433,"journal":{"name":"BMJ medicine","volume":"4 1","pages":"e000954"},"PeriodicalIF":10.0,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12439131/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145082486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-09eCollection Date: 2025-01-01DOI: 10.1136/bmjmed-2025-001343
Aleksi Raudasoja, Sameer Parpia, Jussi M J Mustonen, Robin Vernooij, Petra Falkenbach, Yoshitaka Aoki, Anton Barchuk, Marco H Blanker, Rufus Cartwright, Kathryn Crowder, Herney Andres Garcia-Perdomo, Rachel Gutschon, Alex L E Halme, Tuomas P Kilpeläinen, Ilari Kuitunen, Tiina Lamberg, Eddy Lang, Jenifer Matos, Olli P O Nevalainen, Niko K Nordlund, Negar Pourjamal, Eero Raittio, Patrick O Richard, Philippe D Violette, Jorma T Komulainen, Raija Sipilä, Kari A O Tikkinen
Objective: To evaluate the effectiveness of various de-implementation interventions in primary care, targeting care (treatments or tests) that provides no or limited value for patients (low value care).
Design: Systematic review and meta-analysis.
Data sources: Medline and Scopus databases, from inception to 10 July 2024.
Eligibility criteria for selecting studies: Randomised trials comparing de-implementation interventions with placebo or sham intervention, no intervention, or other de-implementation intervention strategies in primary care. Eligible trials provided information on the use of low value care, total volume of care, appropriate care, and health outcomes.
Data extraction and synthesis: Titles, abstracts, and full texts were screened, data were extracted, and risk of bias was assessed independently and in duplicate. Random effects meta-analyses were conducted, and the certainty of evidence was assessed with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.
Results: 13 008 abstracts were screened and 140 were eligible for inclusion in the study. Median follow-up was 287 days (interquartile range 180-365). In 75 (54%) trials the aim was to reduce the use of antibiotics, in 42 (30%) to reduce other drug treatments, in 17 (12%) to reduce imaging, and in 15 (11%) to reduce laboratory testing. The certainty of the evidence was moderate that provider education combined with audit and feedback reduced the use of targeted low value care (odds ratio 0.73, 95% confidence interval (95% CI) 0.63 to 0.84). Provider education (0.86, 95% CI 0.72 to 1.03), audit and feedback (0.82, 0.67 to 1.00), and patient education (0.70, 0.30 to 1.66), and a combination of these strategies (point estimates for odds ratios ranging from 0.57 to 0.64) may reduce the use of targeted low value care (low certainty of evidence for all).
Conclusions: The results suggested with moderate certainty of evidence that provider education combined with audit and feedback reduced the use of targeted low value care. Individual strategies may slightly reduce the use of targeted low value care, but achieving a meaningful impact on low value care may require the use of multiple strategies. The results may be useful for patients, clinicians, policy makers, and guideline developers when deciding on future de-implementation strategies and research priorities.
{"title":"Effectiveness of different de-implementation strategies in primary care: systematic review and meta-analysis.","authors":"Aleksi Raudasoja, Sameer Parpia, Jussi M J Mustonen, Robin Vernooij, Petra Falkenbach, Yoshitaka Aoki, Anton Barchuk, Marco H Blanker, Rufus Cartwright, Kathryn Crowder, Herney Andres Garcia-Perdomo, Rachel Gutschon, Alex L E Halme, Tuomas P Kilpeläinen, Ilari Kuitunen, Tiina Lamberg, Eddy Lang, Jenifer Matos, Olli P O Nevalainen, Niko K Nordlund, Negar Pourjamal, Eero Raittio, Patrick O Richard, Philippe D Violette, Jorma T Komulainen, Raija Sipilä, Kari A O Tikkinen","doi":"10.1136/bmjmed-2025-001343","DOIUrl":"10.1136/bmjmed-2025-001343","url":null,"abstract":"<p><strong>Objective: </strong>To evaluate the effectiveness of various de-implementation interventions in primary care, targeting care (treatments or tests) that provides no or limited value for patients (low value care).</p><p><strong>Design: </strong>Systematic review and meta-analysis.</p><p><strong>Data sources: </strong>Medline and Scopus databases, from inception to 10 July 2024.</p><p><strong>Eligibility criteria for selecting studies: </strong>Randomised trials comparing de-implementation interventions with placebo or sham intervention, no intervention, or other de-implementation intervention strategies in primary care. Eligible trials provided information on the use of low value care, total volume of care, appropriate care, and health outcomes.</p><p><strong>Data extraction and synthesis: </strong>Titles, abstracts, and full texts were screened, data were extracted, and risk of bias was assessed independently and in duplicate. Random effects meta-analyses were conducted, and the certainty of evidence was assessed with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.</p><p><strong>Results: </strong>13 008 abstracts were screened and 140 were eligible for inclusion in the study. Median follow-up was 287 days (interquartile range 180-365). In 75 (54%) trials the aim was to reduce the use of antibiotics, in 42 (30%) to reduce other drug treatments, in 17 (12%) to reduce imaging, and in 15 (11%) to reduce laboratory testing. The certainty of the evidence was moderate that provider education combined with audit and feedback reduced the use of targeted low value care (odds ratio 0.73, 95% confidence interval (95% CI) 0.63 to 0.84). Provider education (0.86, 95% CI 0.72 to 1.03), audit and feedback (0.82, 0.67 to 1.00), and patient education (0.70, 0.30 to 1.66), and a combination of these strategies (point estimates for odds ratios ranging from 0.57 to 0.64) may reduce the use of targeted low value care (low certainty of evidence for all).</p><p><strong>Conclusions: </strong>The results suggested with moderate certainty of evidence that provider education combined with audit and feedback reduced the use of targeted low value care. Individual strategies may slightly reduce the use of targeted low value care, but achieving a meaningful impact on low value care may require the use of multiple strategies. The results may be useful for patients, clinicians, policy makers, and guideline developers when deciding on future de-implementation strategies and research priorities.</p><p><strong>Systematic review registration: </strong>PROSPERO CRD42023411768.</p>","PeriodicalId":72433,"journal":{"name":"BMJ medicine","volume":"4 1","pages":"e001343"},"PeriodicalIF":10.0,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12421606/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145042259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-04eCollection Date: 2025-01-01DOI: 10.1136/bmjmed-2024-000992
Lena Marie Paschke, Kerstin Klimke, Maike Below
Objectives: To identify and quantify prescriptions after a covid-19 infection compared with other acute respiratory infections in previously healthy patients and those with chronic disease.
Design: Comparative observational study based on German routine data.
Setting: Ambulatory care of all residents in Germany with statutory health insurance (88% of the German population).
Participants: Adults receiving a diagnosis of covid-19 or an acute respiratory infection between the fourth quarter of 2020 and the second quarter of 2021 who had rarely (70 797 and 173 822 with covid-19 and acute respiratory infection, respectively) or frequently (900 593 and 1 755 691, respectively) accessed outpatient medical care in the past.
Main outcome measures: Difference in differences in the proportion of prescriptions of relevant drugs before and one year after infection.
Results: In patients who used the healthcare system less frequently before their covid-19 infection than afterwards, increases in prescription rates for antidiabetics (difference in differences 0.23%, P=0.007), antithrombotics (0.71%, P=0.02), and cardiovascular drugs like beta blockers (0.25%, P=0.03) were observed compared with patients with other acute respiratory infections. One year after infection, the difference in antidiabetic prescription rates was highest. Although a peak in antihypertensive prescription rates was observed six months after infection, antithrombotics were predominantly prescribed during the acute phase. Conversely, patients who had already used the healthcare system on a regular basis before their infection showed no significant long term increases in prescription rates across the drug groups analysed.
Conclusions: This study supports findings that diseases such as diabetes and cardiovascular disease are more prevalent after covid-19 than after other acute respiratory infections. Because the effect is apparent in real world data, future societal implications should be considered, including increased disease burden and growing demand for medical care owing to the increasing need for drugs.
{"title":"Prescription rates in different groups of outpatients with covid-19 and other acute respiratory infections: comparative observational study based on German routine data.","authors":"Lena Marie Paschke, Kerstin Klimke, Maike Below","doi":"10.1136/bmjmed-2024-000992","DOIUrl":"10.1136/bmjmed-2024-000992","url":null,"abstract":"<p><strong>Objectives: </strong>To identify and quantify prescriptions after a covid-19 infection compared with other acute respiratory infections in previously healthy patients and those with chronic disease.</p><p><strong>Design: </strong>Comparative observational study based on German routine data.</p><p><strong>Setting: </strong>Ambulatory care of all residents in Germany with statutory health insurance (88% of the German population).</p><p><strong>Participants: </strong>Adults receiving a diagnosis of covid-19 or an acute respiratory infection between the fourth quarter of 2020 and the second quarter of 2021 who had rarely (70 797 and 173 822 with covid-19 and acute respiratory infection, respectively) or frequently (900 593 and 1 755 691, respectively) accessed outpatient medical care in the past.</p><p><strong>Main outcome measures: </strong>Difference in differences in the proportion of prescriptions of relevant drugs before and one year after infection.</p><p><strong>Results: </strong>In patients who used the healthcare system less frequently before their covid-19 infection than afterwards, increases in prescription rates for antidiabetics (difference in differences 0.23%, P=0.007), antithrombotics (0.71%, P=0.02), and cardiovascular drugs like beta blockers (0.25%, P=0.03) were observed compared with patients with other acute respiratory infections. One year after infection, the difference in antidiabetic prescription rates was highest. Although a peak in antihypertensive prescription rates was observed six months after infection, antithrombotics were predominantly prescribed during the acute phase. Conversely, patients who had already used the healthcare system on a regular basis before their infection showed no significant long term increases in prescription rates across the drug groups analysed.</p><p><strong>Conclusions: </strong>This study supports findings that diseases such as diabetes and cardiovascular disease are more prevalent after covid-19 than after other acute respiratory infections. Because the effect is apparent in real world data, future societal implications should be considered, including increased disease burden and growing demand for medical care owing to the increasing need for drugs.</p>","PeriodicalId":72433,"journal":{"name":"BMJ medicine","volume":"4 1","pages":"e000992"},"PeriodicalIF":10.0,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12414209/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145024891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-14eCollection Date: 2025-01-01DOI: 10.1136/bmjmed-2025-001369
Daniel G Rayner, Darsh Shah, Si-Cheng Dai, David Gou, Jason Z X Chen, Arnav Agarwal, Reem A Mustafa, Veena Manja, Per Olav Vandvik, Thomas Agoritsas, Farid Foroutan
<p><strong>Objective: </strong>To summarise available evidence regarding the performance metrics of validated prognostic models on cardiovascular and kidney outcomes in adults with type 2 diabetes mellitus.</p><p><strong>Design: </strong>Living systematic review and meta-analysis of observational studies.</p><p><strong>Data sources: </strong>Medline, Embase, Central, and the Cochrane Database of Systematic Reviews from 1 January 2020 to 17 January 2024.</p><p><strong>Eligibility criteria for selecting studies: </strong>Studies validating prognostic models that predicted all cause and cardiovascular mortality, admission to hospital for heart failure, kidney failure, myocardial infarction, or ischaemic stroke in adults with type 2 diabetes mellitus, including people with established cardiovascular disease or chronic kidney disease, or both. Risk models evaluating composite outcomes were not eligible.</p><p><strong>Data synthesis: </strong>For each model and outcome, using a random effects model, the reported discrimination measures were pooled, reported as c statistics. Furthermore, when available, calibration plots were reconstructed and interpreted narratively. The Prediction Model Risk of Bias Assessment (PROBAST) tool was used to assess the risk of bias of each analysed study cohort and the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach to evaluate our certainty in the evidence.</p><p><strong>Results: </strong>6529 publications were identified, of which 35 studies reporting on 13 models were included, all of which were developed for general populations with type 2 diabetes but no established cardiovascular disease or chronic kidney disease. Among the identified models, the Risk Equations for Complications of Type 2 Diabetes (RECODe) and the UK Prospective Diabetes Study Outcomes Model 2 (UKPDS-OM2) evaluated all outcomes except for admission to hospital for heart failure. Relative to a threshold c statistic of 0.7, RECODe had an acceptable discrimination for cardiovascular mortality (0.79, high certainty), probably has an acceptable discrimination for myocardial infarction (0.72, moderate certainty) and stroke (0.71, moderate certainty), and may have an acceptable discrimination for kidney failure (0.76, low certainty). High certainty evidence suggests that UKPDS-OM2 has unacceptable discrimination for myocardial infarction (0.64) and stroke (0.65). RECODe showed acceptable calibration for cardiovascular mortality (high certainty), myocardial infarction (high certainty), and kidney failure (moderate certainty) but had unacceptable calibration for stroke (moderate certainty). UKPDS-OM2 showed acceptable calibration for cardiovascular mortality (moderate certainty), stroke (moderate certainty), and kidney failure (low certainty), but may have unacceptable calibration for myocardial infarction (moderate certainty).</p><p><strong>Conclusion: </strong>13 unique models were identified that evaluated cardiovascul
{"title":"Prognostic models for cardiovascular and kidney outcomes in people with type 2 diabetes: living systematic review and meta-analysis of observational studies.","authors":"Daniel G Rayner, Darsh Shah, Si-Cheng Dai, David Gou, Jason Z X Chen, Arnav Agarwal, Reem A Mustafa, Veena Manja, Per Olav Vandvik, Thomas Agoritsas, Farid Foroutan","doi":"10.1136/bmjmed-2025-001369","DOIUrl":"10.1136/bmjmed-2025-001369","url":null,"abstract":"<p><strong>Objective: </strong>To summarise available evidence regarding the performance metrics of validated prognostic models on cardiovascular and kidney outcomes in adults with type 2 diabetes mellitus.</p><p><strong>Design: </strong>Living systematic review and meta-analysis of observational studies.</p><p><strong>Data sources: </strong>Medline, Embase, Central, and the Cochrane Database of Systematic Reviews from 1 January 2020 to 17 January 2024.</p><p><strong>Eligibility criteria for selecting studies: </strong>Studies validating prognostic models that predicted all cause and cardiovascular mortality, admission to hospital for heart failure, kidney failure, myocardial infarction, or ischaemic stroke in adults with type 2 diabetes mellitus, including people with established cardiovascular disease or chronic kidney disease, or both. Risk models evaluating composite outcomes were not eligible.</p><p><strong>Data synthesis: </strong>For each model and outcome, using a random effects model, the reported discrimination measures were pooled, reported as c statistics. Furthermore, when available, calibration plots were reconstructed and interpreted narratively. The Prediction Model Risk of Bias Assessment (PROBAST) tool was used to assess the risk of bias of each analysed study cohort and the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach to evaluate our certainty in the evidence.</p><p><strong>Results: </strong>6529 publications were identified, of which 35 studies reporting on 13 models were included, all of which were developed for general populations with type 2 diabetes but no established cardiovascular disease or chronic kidney disease. Among the identified models, the Risk Equations for Complications of Type 2 Diabetes (RECODe) and the UK Prospective Diabetes Study Outcomes Model 2 (UKPDS-OM2) evaluated all outcomes except for admission to hospital for heart failure. Relative to a threshold c statistic of 0.7, RECODe had an acceptable discrimination for cardiovascular mortality (0.79, high certainty), probably has an acceptable discrimination for myocardial infarction (0.72, moderate certainty) and stroke (0.71, moderate certainty), and may have an acceptable discrimination for kidney failure (0.76, low certainty). High certainty evidence suggests that UKPDS-OM2 has unacceptable discrimination for myocardial infarction (0.64) and stroke (0.65). RECODe showed acceptable calibration for cardiovascular mortality (high certainty), myocardial infarction (high certainty), and kidney failure (moderate certainty) but had unacceptable calibration for stroke (moderate certainty). UKPDS-OM2 showed acceptable calibration for cardiovascular mortality (moderate certainty), stroke (moderate certainty), and kidney failure (low certainty), but may have unacceptable calibration for myocardial infarction (moderate certainty).</p><p><strong>Conclusion: </strong>13 unique models were identified that evaluated cardiovascul","PeriodicalId":72433,"journal":{"name":"BMJ medicine","volume":"4 1","pages":"e001369"},"PeriodicalIF":10.0,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12359462/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144884411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-10eCollection Date: 2025-01-01DOI: 10.1136/bmjmed-2024-001283
Epaminondas Markos Valsamis, Adrian Sayers, Jie Ma, Paula Dhiman, Stephen E Gwilym, Jonathan L Rees
Objective: To determine the importance of comorbidity measures when predicting mortality and revision surgery after elective primary shoulder replacement surgery.
Design: Population based cohort study.
Setting: Linked data from the National Joint Registry and NHS Hospital Episode Statistics were used to identify all elective primary shoulder replacements in England, 6 January 2012 to 30 March 2022.
Participants: 37 176 consenting patients, aged 18-100 years, who had elective primary shoulder replacement surgery.
Main outcome measures: Risk of mortality at 90 and 365 days, and risk of long term revision surgery after the primary surgery.
Results: 37 176 primary shoulder replacement procedures were included; 102 patients died within 90 days and 445 within 365 days of the primary surgery. 1219 patients had revision surgery over a maximum follow-up period of >10 years. The addition of comorbidity measures derived from Hospital Episode Statistics (Charlson comorbidity index with summary hospital mortality index weights, Elixhauser comorbidity index, and hospital frailty risk score) to simpler models resulted in little improvement in predictive performance. Optimism adjusted performance (C index) of the models that included age, sex, American Society of Anesthesiologists (ASA) grade, and main surgical indication was 0.76 (95% confidence interval (CI) 0.72 to 0.81) for 90 day mortality, 0.74 (0.71 to 0.76) for 365 day mortality, and 0.64 (0.63 to 0.66) for revision surgery. The best performing models that included a comorbidity measure had an optimism adjusted C index of 0.77 (95% CI 0.73 to 0.81) for 90 day mortality, 0.76 (0.74 to 0.78) for 365 day mortality, and 0.65 (0.63 to 0.66) for revision surgery. Heterogeneity in model performance across regions of England was low, and decision curve analysis showed minimal improvement in net benefit when including comorbidity measures.
Conclusions: In this study, patient comorbidity scores added little improvement to simpler models that included age, sex, ASA grade, and main surgical indication for predicting mortality and revision surgery after elective primary shoulder replacement surgery. This improvement needs to be balanced against the additional challenges of routine data linkage to obtain these scores.
{"title":"Evaluation of comorbidity measures for predicting mortality and revision surgery after elective primary shoulder replacement surgery based on data from the National Joint Registry and Hospital Episode Statistics for England: population based cohort study.","authors":"Epaminondas Markos Valsamis, Adrian Sayers, Jie Ma, Paula Dhiman, Stephen E Gwilym, Jonathan L Rees","doi":"10.1136/bmjmed-2024-001283","DOIUrl":"10.1136/bmjmed-2024-001283","url":null,"abstract":"<p><strong>Objective: </strong>To determine the importance of comorbidity measures when predicting mortality and revision surgery after elective primary shoulder replacement surgery.</p><p><strong>Design: </strong>Population based cohort study.</p><p><strong>Setting: </strong>Linked data from the National Joint Registry and NHS Hospital Episode Statistics were used to identify all elective primary shoulder replacements in England, 6 January 2012 to 30 March 2022.</p><p><strong>Participants: </strong>37 176 consenting patients, aged 18-100 years, who had elective primary shoulder replacement surgery.</p><p><strong>Main outcome measures: </strong>Risk of mortality at 90 and 365 days, and risk of long term revision surgery after the primary surgery.</p><p><strong>Results: </strong>37 176 primary shoulder replacement procedures were included; 102 patients died within 90 days and 445 within 365 days of the primary surgery. 1219 patients had revision surgery over a maximum follow-up period of >10 years. The addition of comorbidity measures derived from Hospital Episode Statistics (Charlson comorbidity index with summary hospital mortality index weights, Elixhauser comorbidity index, and hospital frailty risk score) to simpler models resulted in little improvement in predictive performance. Optimism adjusted performance (C index) of the models that included age, sex, American Society of Anesthesiologists (ASA) grade, and main surgical indication was 0.76 (95% confidence interval (CI) 0.72 to 0.81) for 90 day mortality, 0.74 (0.71 to 0.76) for 365 day mortality, and 0.64 (0.63 to 0.66) for revision surgery. The best performing models that included a comorbidity measure had an optimism adjusted C index of 0.77 (95% CI 0.73 to 0.81) for 90 day mortality, 0.76 (0.74 to 0.78) for 365 day mortality, and 0.65 (0.63 to 0.66) for revision surgery. Heterogeneity in model performance across regions of England was low, and decision curve analysis showed minimal improvement in net benefit when including comorbidity measures.</p><p><strong>Conclusions: </strong>In this study, patient comorbidity scores added little improvement to simpler models that included age, sex, ASA grade, and main surgical indication for predicting mortality and revision surgery after elective primary shoulder replacement surgery. This improvement needs to be balanced against the additional challenges of routine data linkage to obtain these scores.</p>","PeriodicalId":72433,"journal":{"name":"BMJ medicine","volume":"4 1","pages":"e001283"},"PeriodicalIF":10.0,"publicationDate":"2025-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12336573/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144823320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-07eCollection Date: 2025-01-01DOI: 10.1136/bmjmed-2024-001313
Marcel Ballin, Viktor H Ahlqvist, Daniel Berglind, Mattias Brunström, Angel Herraiz-Adillo, Pontus Henriksson, Martin Neovius, Francisco B Ortega, Anna Nordström, Peter Nordström
<p><strong>Objective: </strong>To examine the association between adolescent cardiorespiratory fitness and risk of type 2 diabetes in late adulthood, including the potential influence of unobserved familial confounding on the association.</p><p><strong>Design: </strong>Nationwide sibling controlled cohort study.</p><p><strong>Setting: </strong>Swedish Military Service Conscription Register, Sweden, 1972-95, with Multi-Generation Register for identifying full siblings. National Patient Register and Prescribed Drug Register for data on diagnoses of type 2 diabetes, deaths from National Cause of Death Register, and Statistics Sweden for emigration and socioeconomic data.</p><p><strong>Participants: </strong>1 124 049 Swedish men who participated in mandatory military conscription examinations with completed standardised cardiorespiratory fitness testing. Participants were followed up until 31 December 2023.</p><p><strong>Main outcome measures: </strong>Type 2 diabetes, defined as a composite endpoint of diagnosis in inpatient or specialist outpatient care and dispensation of antidiabetic drug treatment, until 31 December 2023.</p><p><strong>Results: </strong>1 124 049 men, including 477 453 full siblings, with a mean age of 18.3 (standard deviation 0.7) years at baseline were included. During follow-up, 115 958 men (10.3%) and 48 089 full siblings (10.1%) had a first type 2 diabetes event at a median age of 53.4 (interquartile range 47.6-59.3) years. Cardiorespiratory fitness was categorised into deciles (referred to as groups, with group 1 being the lowest fitness level and group 10 the highest). In a cohort analysis, the adjusted hazard ratio in fitness group 2 versus fitness group 1 was 0.83 (95% confidence interval (CI) 0.81 to 0.85), with a difference in the standardised cumulative incidence at age 65 years of 4.3 (95% CI 3.8 to 4.8) percentage points, decreasing to a hazard ratio of 0.38 (0.36 to 0.39; incidence difference 17.8 (17.3 to 18.3) percentage points) in fitness group 10. When comparing full siblings, and thus controlling for all unobserved shared behavioural, environmental, and genetic confounders, the association was replicated, but with a reduction in magnitude. The hazard ratio in fitness group 2 was 0.89 (95% CI 0.85 to 0.94; incidence difference 2.3 (1.3 to 3.3) percentage points) and 0.53 (0.50 to 0.57; incidence difference 10.9 (9.7 to 12.1) percentage points) in fitness group 10. Hypothetically moving all participants in fitness group 1 to fitness group 2 was estimated to prevent 7.2% (95% CI 6.4% to 8.0%) of events at age 65 years in the cohort analysis versus 4.6% (2.6% to 6.5%) in the full sibling analysis, whereas hypothetically moving all participants to fitness group 10 was estimated to prevent 35.6% (34.1% to 37.0%) versus 24.3% (20.5 to 28.0) of events. Indications of effect modification by overweight status were found, where the association was smaller in those with overweight than in those without overweight, parti
目的:探讨青少年心肺健康与成年后期2型糖尿病风险之间的关系,包括未观察到的家族混杂因素对这种关系的潜在影响。设计:全国同胞对照队列研究。背景:1972年至1995年,瑞典兵役征召登记簿(Swedish Military Service征兵登记簿)和多代登记簿(Multi-Generation Register),用于识别全兄妹。国家患者登记册和处方药登记册中的2型糖尿病诊断数据,国家死因登记册中的死亡数据,以及瑞典统计局的移民和社会经济数据。参与者:1 124 049名参加强制性征兵考试并完成标准化心肺功能测试的瑞典男性。参与者被随访至2023年12月31日。主要结局指标:2型糖尿病,定义为住院或专科门诊诊断和降糖药物治疗的复合终点,直至2023年12月31日。结果:纳入1 124 049名男性,包括477 453名全兄妹,基线时平均年龄为18.3岁(标准差0.7)。在随访期间,115 958名男性(10.3%)和48 089名全兄妹(10.1%)首次发生2型糖尿病事件,中位年龄为53.4岁(四分位数间距为47.6-59.3岁)。心肺健康被分为十分位数(称为组,第1组的健康水平最低,第10组的健康水平最高)。在队列分析中,健身组2与健身组1的校正风险比为0.83(95%可信区间(CI) 0.81至0.85),65岁时标准化累积发病率的差异为4.3 (95% CI 3.8至4.8)个百分点,风险比降至0.38(0.36至0.39;健身组发病率差异17.8(17.3 ~ 18.3)个百分点。当对全兄妹进行比较,从而控制所有未观察到的共同行为、环境和遗传混杂因素时,这种关联得到了复制,但程度有所降低。健身2组的危险比为0.89 (95% CI 0.85 ~ 0.94;发病率差2.3(1.3 ~ 3.3)个百分点)和0.53 (0.50 ~ 0.57);健身组发病率差异10.9(9.7 ~ 12.1)个百分点。假设将健身组1的所有参与者转移到健身组2,在队列分析中估计可以预防7.2% (95% CI 6.4%至8.0%)的65岁事件,而在全同胞分析中则为4.6%(2.6%至6.5%),而假设将所有参与者转移到健身组10估计可以预防35.6%(34.1%至37.0%)的事件,而24.3%(20.5至28.0)的事件。研究发现,超重状态改变了影响的迹象,超重人群的相关性小于没有超重的人群,特别是在全兄弟姐妹分析中。结论:研究结果表明,青少年心肺健康对成年后期2型糖尿病的发展可能很重要,但传统的观察性分析可能对影响的程度给出了有偏差的估计。
{"title":"Cardiorespiratory fitness in adolescence and risk of type 2 diabetes in late adulthood in one million Swedish men: nationwide sibling controlled cohort study.","authors":"Marcel Ballin, Viktor H Ahlqvist, Daniel Berglind, Mattias Brunström, Angel Herraiz-Adillo, Pontus Henriksson, Martin Neovius, Francisco B Ortega, Anna Nordström, Peter Nordström","doi":"10.1136/bmjmed-2024-001313","DOIUrl":"10.1136/bmjmed-2024-001313","url":null,"abstract":"<p><strong>Objective: </strong>To examine the association between adolescent cardiorespiratory fitness and risk of type 2 diabetes in late adulthood, including the potential influence of unobserved familial confounding on the association.</p><p><strong>Design: </strong>Nationwide sibling controlled cohort study.</p><p><strong>Setting: </strong>Swedish Military Service Conscription Register, Sweden, 1972-95, with Multi-Generation Register for identifying full siblings. National Patient Register and Prescribed Drug Register for data on diagnoses of type 2 diabetes, deaths from National Cause of Death Register, and Statistics Sweden for emigration and socioeconomic data.</p><p><strong>Participants: </strong>1 124 049 Swedish men who participated in mandatory military conscription examinations with completed standardised cardiorespiratory fitness testing. Participants were followed up until 31 December 2023.</p><p><strong>Main outcome measures: </strong>Type 2 diabetes, defined as a composite endpoint of diagnosis in inpatient or specialist outpatient care and dispensation of antidiabetic drug treatment, until 31 December 2023.</p><p><strong>Results: </strong>1 124 049 men, including 477 453 full siblings, with a mean age of 18.3 (standard deviation 0.7) years at baseline were included. During follow-up, 115 958 men (10.3%) and 48 089 full siblings (10.1%) had a first type 2 diabetes event at a median age of 53.4 (interquartile range 47.6-59.3) years. Cardiorespiratory fitness was categorised into deciles (referred to as groups, with group 1 being the lowest fitness level and group 10 the highest). In a cohort analysis, the adjusted hazard ratio in fitness group 2 versus fitness group 1 was 0.83 (95% confidence interval (CI) 0.81 to 0.85), with a difference in the standardised cumulative incidence at age 65 years of 4.3 (95% CI 3.8 to 4.8) percentage points, decreasing to a hazard ratio of 0.38 (0.36 to 0.39; incidence difference 17.8 (17.3 to 18.3) percentage points) in fitness group 10. When comparing full siblings, and thus controlling for all unobserved shared behavioural, environmental, and genetic confounders, the association was replicated, but with a reduction in magnitude. The hazard ratio in fitness group 2 was 0.89 (95% CI 0.85 to 0.94; incidence difference 2.3 (1.3 to 3.3) percentage points) and 0.53 (0.50 to 0.57; incidence difference 10.9 (9.7 to 12.1) percentage points) in fitness group 10. Hypothetically moving all participants in fitness group 1 to fitness group 2 was estimated to prevent 7.2% (95% CI 6.4% to 8.0%) of events at age 65 years in the cohort analysis versus 4.6% (2.6% to 6.5%) in the full sibling analysis, whereas hypothetically moving all participants to fitness group 10 was estimated to prevent 35.6% (34.1% to 37.0%) versus 24.3% (20.5 to 28.0) of events. Indications of effect modification by overweight status were found, where the association was smaller in those with overweight than in those without overweight, parti","PeriodicalId":72433,"journal":{"name":"BMJ medicine","volume":"4 1","pages":"e001313"},"PeriodicalIF":10.0,"publicationDate":"2025-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12336507/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144823319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}