Incidence of Hospitalization for Heart Failure and Case-Fatality Among 3.25 Million People With and Without Diabetes Mellitus

Abstract

Background—Recent clinical trials of new glucose-lowering treatments have drawn attention to the importance of hospitalisation for heart failure as a complication of diabetes. However, the epidemiology is not well described, particularly for type 1 diabetes. We examined the incidence and case-fatality of heart failure hospitalisations in the entire population aged 30 and older resident in Scotland during 2004 to 2013. Methods—Date and type of diabetes diagnosis were linked to heart failure hospitalisations and deaths using the national Scottish registers. Incidence rates and case-fatality were estimated in regression models (quasi-Poisson and logistic regression respectively). All estimates are adjusted for age, sex, socio-economic status and calendar-year. Results—Over the 10-year period of the study, among 3.25 million people there were 91,429, 22,959 and 1,313 incident heart failure events among those without diabetes, with type 2, and type 1 diabetes respectively. The crude incidence rates of heart failure hospitalisation were therefore 2.4, 12.4 and 5.6 per 1000 person-years for these three groups. Heart failure hospitalisation incidence was higher in people with diabetes, regardless of type, than in people without. Relative differences were smallest for older men, in whom the difference was nonetheless large (men aged 80, rate ratio 1.78; 95% CI 1.45 to 2.19). Rates declined similarly, by 0.2% per calendar-year, in people with type 2 diabetes and without diabetes. Rates fell faster, however, in those with type 1 diabetes (2.2% per calendar-year, RR for type 1/calendar-year interaction 0.978; 95% CI 0.959 to 0.998).30-day case-fatality was similar among people with type 2 diabetes and without diabetes, but was higher in type 1 diabetes for men (OR 0.96; 95% CI 0.95 to 0.96) and women (OR 0.98; 95% CI 0.97 to 0.98). Case-fatality declined over time for all groups (3.3% per calendar-year, OR per calendar-year 0.967; 95% CI 0.961 to 0.973). Conclusions—Despite falling incidence, particularly in type 1 diabetes, heart failure remains around 2-fold higher than in people without diabetes, with higher case-fatality in those with type 1 diabetes. These findings support the view that heart failure is an under-recognised and important complication in diabetes, particularly for type 1 disease.