Is diabetes a coronary risk equivalent? Systematic review and meta‐analysis

Abstract

Aims To determine whether patients with diabetes without prior myocardial infarction (MI) have the same risk of total coronary heart disease (CHD) events as non-diabetic patients with previous myocardial infarction.Methods Using MEDLINE , EMBASE , Cochrane and MeSH in this systematic review and meta-analysis, extensive searching was carried out by cross-referencing from original articles and reviews. The study consisted of cohort or observational studies with hard clinical endpoints, including total CHD events (fatal or non-fatal myocardial infarction), stratified for patients with diabetes but no previous myocardial infarction, and patients without diabetes but with previous myocardial infarction. Studies with less than 100 subjects, follow-up of less than 4 years and/or without provisions for calculating CHD event rates were excluded. The review of articles and data extraction was performed by two independent authors, with any disagreements resolved by consensus.Results Thirteen studies were included involving 45 108 patients. The duration of follow-up was 5-25 years (mean 13.4 years) and the age range was 25-84 years. Patients with diabetes without prior myocardial infarction have a 43% lower risk of developing total CHD events compared with patients without diabetes with previous myocardial infarction (summary odds ratio 0.56, 95% confidence interval 0.53-0.60). ConclusionThis meta-analysis did not support the hypothesis that diabetes is a 'coronary heart disease equivalent'. Public health decisions to initiate cardio-protective drugs in patients with diabetes for primary CHD prevention should therefore be based on appropriate patients' CHD risk estimates rather than a 'blanket' approach of treatment. Diabet. Med. 26, 142-148 (2009) Keywords coronary risk equivalent, diabetes, meta-analysis Abbreviations CHD, coronary heart disease; CI, confidence interval IntroductionIncreased cardiovascular morbidity and mortality in patients with Type 2 diabetes is well established; diabetes is associated with twice the risk of incident coronary heart disease (CHD) and ischaemic stroke and 2-4 times increased risk of CHD and stroke mortality compared with patients without diabetes [1][2][3]. As more than 65% of deaths in patients with diabetes are from cardiovascular causes [4], the management of diabetes mellitus has shifted from a glucocentric approach to an aggressive multifactorial strategy to identify and target patients' cardiovascular risk factors.The widely quoted study by Haffner and colleagues has suggested that people with diabetes without prior myocardial infarction have a similar risk of CHD to those without diabetes who have had a myocardial infarction [5]. The study suggests that patients with diabetes should be treated as if they had existing CHD. This observational study, performed in a Finnish population cohort had some weaknesses, such as the lack of power to detect differences between two groups of patients. In addition, patients in this study were self-selected rather than derived from a po...

Diabetes and Prior Coronary Heart Disease are Not Necessarily Risk Equivalent for Future Coronary Heart Disease Events

“…2 This led to the concept of diabetes as a CHD risk equivalent, which has been challenged and remains controversial. 5,6 A meta-analysis of 13 studies including 19,072 individuals with diabetes noted that individuals with diabetes alone had a 43 % lower risk of developing CHD than those with prior CHD but without diabetes. 5 Our data also demonstrate that individuals with prevalent diabetes alone had substantially lower risk (adjusted HR 0.61; 95 % CI, 0.60-0.63) of developing CHD than those without diabetes and with prior CHD.…”

“…5,6 A meta-analysis of 13 studies including 19,072 individuals with diabetes noted that individuals with diabetes alone had a 43 % lower risk of developing CHD than those with prior CHD but without diabetes. 5 Our data also demonstrate that individuals with prevalent diabetes alone had substantially lower risk (adjusted HR 0.61; 95 % CI, 0.60-0.63) of developing CHD than those without diabetes and with prior CHD. Our study confirms in a real-world population the findings of the previous meta-analysis based on more controlled epidemiologic cohorts.…”

“…The present study is also unique in having no limitations associated with the meta-analysis, including heterogeneous population, lack of access to individual patient data, and inability to adjust for differences in age, sex and confounders across the studies. 5 Furthermore, only a limited number of studies had data for both men and women. 5 Finally, our single study with a diabetes population of 138,507 individuals is several-fold larger than all the studies in that analysis combined.…”

“…4 The assertion that all patients with diabetes are CHD equivalent has been controversial. 5,6 Existing evidence is based on relatively small studies with various limitations. Some studies were limited to a single gender, 7-9 while others were based on self-reported diagnosis of diabetes.…”

“…10,11 Some lacked the ability to adjust for important confounding risk factors. 12,13 Most of the studies have comprised cohorts from the 1990s, 5 and only a few studies have been able to evaluate the impact of the duration of diabetes. 7,8,14 There is also a paucity of data among relatively young (30-40 years) patients with diabetes.…”