Mortality in diabetes compared with previous cardiovascular disease: a gender-specific meta-analysis.
OBJECTIVE
Diabetes has been described as a cardiovascular disease (CVD) risk equivalent. There is evidence, however, that its impact may differ between women and men. For this reason, our study aimed to obtain gender-specific hazard ratios (HRs) comparing diabetes and CVD patients in terms of all-cause, CVD and coronary heart disease (CHD) mortality.


METHODS
Individuals with diabetes (without CVD) and those with CVD (without diabetes) were examined through a systematic review of articles that provided gender-specific HRs for mortality. Searches included Medline, Embase and the Cochrane Library database (from January 1998 to December 2009) and exploded MeSH headings [cardiovascular diseases, risk, epidemiologic studies, case-control studies, cohort studies, mortality, outcome assessment (health care), sex factors, survival analysis and diabetes mellitus, type 2]. Two observers selected and reviewed the studies and hierarchical Bayesian random-effects models were used to combine HRs, thereby accommodating any between-study differences through inclusion of a between-study variance in HRs.


RESULTS
Out of 5425 studies, nine were relevant (0.17%). CVD and CHD mortality in men was lower for diabetes alone (CVD mortality HR: 0.82, 95% CrI: 0.69-0.98; CHD mortality HR: 0.73, 95% CrI: 0.65-0.83). In contrast, rates appeared to be higher in women with diabetes alone (CVD mortality HR: 1.29, 95% CrI: 0.79-2.26; CHD mortality HR: 1.28, 95% CrI: 0.75-2.22), although wide credible intervals precluded any definitive conclusions. All-cause mortality in men was similar for diabetes and previous CVD (HR: 1.02, 95% CrI: 0.93-1.12) whereas, among women, it was at least as high and possibly higher for diabetes alone (HR: 1.25, 95% CrI: 0.89-1.76).


CONCLUSIONS
Compared with previous CVD, diabetes alone leads to lower CVD and CHD mortality risk in men, and similar all-cause mortality. In contrast, although further studies are needed, it is possible that diabetes leads to higher CVD, CHD and all-cause mortality in women.
Department of Medicine, McGill University, Montreal, Quebec, Canada.
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Lee
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Joseph
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Colosimo
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Dasgupta
D000328:Adult; D000368:Aged; D002318:Cardiovascular Diseases / Q000401:mortality*; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000401:mortality*; D003925:Diabetic Angiopathies / Q000401:mortality*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D017678:Sex Distribution; D012737:Sex Factors; D016019:Survival Analysis