Predicting mortality in people with Type 2 diabetes mellitus after major complications: a study using Swedish National Diabetes Register data

Aim To predict mortality risk and life expectancy for patients with Type 2 diabetes after a major diabetes-related complication. Methods The study sample, taken from the Swedish National Diabetes Register, consisted of 20 836 people with Type 2 diabetes who had their first major complication (myocardial infarction, stroke, heart failure, amputation or renal failure) between January 2001 and December 2007. A Gompertz proportional hazards model was derived which determined significant risk factors associated with mortality and was used to estimate life expectancies. Results Risk of death changed over time according to type of complication, with myocardial infarction initally having the highest initial risk of death, but after the first month, the risk was higher for heart failure, renal failure and amputation. Other factors that increased the risk of death were male gender (hazard ratio 1.06, 95% CI 1.02-1.12), longer duration of diabetes (hazard ratio 1.07 per 10 years, 95% CI 1.04-1.10), smoking (hazard ratio 1.51, 95% CI 1.40-1.63) and macroalbuminuria (hazard ratio 1.14, 95% CI 1.06-1.22). Low BMI, low systolic blood pressure and low estimated GFR also increased mortality risk. Life expectancy was highest after a stroke, myocardial infarction or heart failure, lower after amputation and lowest after renal failure. Smoking and poor renal function were the risk factors which had the largest impact on reducing life expectancy. Conclusions Risk of death and life expectancy differs substantially among the major complications of diabetes, and factors significantly increasing risk included smoking, low estimated GFR and albuminuria.