Excess mortality following hip fracture in patients with diabetes according to age: a nationwide population-based cohort study of 154,047 hip fracture patients

Abstract

Objective: to test the hypothesis that excess mortality conferred by diabetes following hip fracture decreases with advancing age.

Methods: a nationwide population-based cohort study including 154,047 patients who were admitted with a hip fracture in Denmark from 1996 to 2012. Information on hip fracture diagnosis, diabetes, other comorbidities, and the primary outcome all-cause mortality was collected using the national Danish health registries. The association between diabetes and all-cause mortality according to age was assessed using Cox proportional hazards regression in the age categories: <50, 50-59, 60-69, 70-79, 80-89 and ≥90 years.

Results: during a median follow-up of 3 years (interquartile range: 1-6 years, 603,091 person-years) 114,990 died from any cause. In total, 8% (n = 12,158) of the patients had diabetes at baseline and had unadjusted, and age, sex and Charlson Comorbidity Index adjusted hazard ratios for all-cause mortality of 1.19 (95% confidence interval: 1.16-1.21) and 1.14 (1.12-1.17) as compared to patients without diabetes. The sex and Charlson Comorbidity Index adjusted hazard ratios according to age were 1.64 (1.34-2.02) for patients <50 years, 1.26 (1.12-1.40) for patients 50-59 years, 1.21 (1.13-1.29) for patients 60-69 years, 1.11 (1.07-1.16) for patients 70-79 years, 1.10 (1.07-1.14) for patients 80-89 years and 1.09 (1.02-1.16) for patients ≥90 years. There was a statistically significant interaction between diabetes and age (P < 0.001).

Conclusions: diabetes is associated with excess mortality following hip fracture across all ages, but the excess mortality decreases with advancing age.

Keywords: ageing; endocrinology; epidemiology; fragility fracture; osteoporosis; survival.