Abstract
Aims/hypothesisThere is continuing debate about the net benefits of population screening for type 2 diabetes. We compared the risk of cardiovascular disease (CVD) and mortality among incident cases of type 2 diabetes in a screened group with those in an unscreened group.MethodsIn this register-based non-randomised controlled trial, eligible individuals were all men and women aged 40–69 years without known diabetes, registered with a general practice in Denmark (n = 1,912,392). Between 2001 and 2006, 153,107 individuals registered with 181 practices participating in the Anglo–Danish–Dutch Study of Intensive Treatment in People with Screen-Detected Diabetes in Primary Care (ADDITION)-Denmark study were sent a diabetes-risk-score questionnaire. Individuals at moderate-to-high risk were invited to visit their family doctor for assessment of diabetes status and cardiovascular risk (screening group). The 1,759,285 individuals registered with all other practices in Denmark constituted the retrospectively constructed no-screening (control) group. In this post hoc analysis, we identified individuals from the screening and no-screening groups who were diagnosed with diabetes between 2001 and 2009 (n = 139,075), and compared risk of CVD and mortality in these groups between 2001 and 2012.ResultsIn the screening group, 27,177/153,107 (18%) individuals attended for screening, of whom 1533 were diagnosed with diabetes. Between 2001 and 2009, 13,992 people were newly diagnosed with diabetes in the screening group (including those diagnosed by screening) and 125,083 in the no-screening group. Between 2001 and 2012, the risks of CVD and mortality were lower among individuals with diabetes in the screening group compared with individuals with diabetes in the no-screening (control) group (CVD HR 0.84, 95% CI 0.80, 0.89; mortality HR 0.79, 95% CI 0.74, 0.84).Conclusions/interpretationA single round of diabetes screening and cardiovascular risk assessment in middle-aged Danish adults in general practice was associated with a significant reduction in risk of all-cause mortality and CVD events in those diagnosed with diabetes.
Highlights
The potential benefits of screening and early treatment for type 2 diabetes have been widely debated
The 1,759,285 individuals registered with all other practices in Denmark constituted the retrospectively constructed no-screening group. In this post hoc analysis, we identified individuals from the screening and noscreening groups who were diagnosed with diabetes between 2001 and 2009 (n = 139,075), and compared risk of cardiovascular disease (CVD) and mortality in these groups between 2001 and 2012
Results from the Anglo–Danish– Dutch Study of Intensive Treatment In People with ScreenDetected Diabetes in Primary Care (ADDITION)-Europe (ClinicalTrials.gov, number NCT00237549) showed that individuals diagnosed with diabetes and treated earlier had a risk of mortality that was similar to that reported for people of the same age without diabetes in the general population in Denmark [12]
Summary
The potential benefits of screening and early treatment for type 2 diabetes have been widely debated. Trials of population-based screening for type 2 diabetes [10] and related cardiovascular risk factors [11] have failed to show significant overall benefit. One of the challenges of demonstrating potential benefit for those found to have diabetes following screening is that it would not be ethical to conduct a clinical trial of screening and early intervention compared with screening and delayed intervention [13]. We cannot directly observe the magnitude of cardiovascular risk reduction that might occur among individuals with diabetes found by screening compared with those with no screening and no treatment until the time of clinical diagnosis [5]. Comparing screen-detected individuals with clinically diagnosed individuals in a parallel cohort design tends to overestimate benefit because of lead and length time biases
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