Multiplicative Risk of Diabetes, Stroke, and MI on Mortality

Study Questions:

What reductions in life expectancy are associated with cardiometabolic multimorbidity?

Methods:

This was an analysis of participant data from the Emerging Risk Factors Collaboration (689,300 participants; 91 cohorts; years of baseline surveys: 1960-2007; latest mortality follow-up: April 2013; 128,843 deaths) and the UK Biobank (499,808 participants; years of baseline surveys: 2006-2010; latest mortality follow-up: November 2013; 7,995 deaths). Cardiometabolic multimorbidity was defined as two or more of the following: diabetes mellitus, stroke, and myocardial infarction (MI). Hypertension was not included in the definition of cardiometabolic multimorbidity. Participants were categorized into the following eight mutually exclusive groups according to baseline disease: 1) diabetes, 2) stroke, 3) MI, 4) diabetes and MI, 5) diabetes and stroke, 6) stroke and MI, 7) diabetes, stroke, and MI, and 8) none of these (reference group). The main outcomes were all-cause mortality and estimated reductions in life expectancy.

Results:

In the Emerging Risk Factors Collaboration analysis and compared with the reference group, the age- and sex-adjusted hazard ratios [HRs] for mortality were 1.9 (95% confidence interval [CI], 1.8-2.0) for participants with a history of diabetes; 2.1 (95% CI, 2.0-2.2), history of stroke; 2.0 (95% CI, 1.9-2.2), history of MI; 3.7 (95% CI, 3.3-4.1), diabetes and MI; 3.8 (95% CI, 3.5-4.2), diabetes and stroke; 3.5 (95% CI, 3.1-4.0), stroke and MI; and 6.9 (95% CI, 5.7-8.3) in those with diabetes, stroke, and MI. These HRs were similar to those obtained from analysis of data from the UK Biobank. At the age of 60 years, a history of any of two of these conditions was associated with 12 years of reduced life expectancy, and a history of all three of these conditions was associated with 15 years of reduced life expectancy.

Conclusions:

Any combination of diabetes, stroke, or MI was associated with multiplicative mortality risk, and life expectancy was substantially lower in people with cardiometabolic multimorbidity.

Perspective:

This is an important analysis that draws attention to the multiplicative risk of cardiometabolic multimorbidity. The associations of cardiovascular disease and diabetes appear to be non-overlapping. As the authors emphasize, the import of this observation is the necessity to not only prevent cardiovascular disease in individuals who already have diabetes, but to advert diabetes in those who have cardiovascular disease. Although the authors did not include hypertension in their definition of cardiometabolic multimorbidity, the analysis draws attention to the substantially lower life expectancy in those with cardiometabolic multimorbidity.

Clinical Topics: Diabetes and Cardiometabolic Disease, Prevention

Keywords: Diabetes Mellitus, Life Expectancy, Metabolic Syndrome X, Myocardial Infarction, Primary Prevention, Risk Factors, Stroke


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