Cause-specific excess mortality after hip fracture: the Norwegian Epidemiologic Osteoporosis Studies (NOREPOS)

Abstract

Background Information on cause of death may help appraise the degree to which the high excess mortality after hip fracture refects pre-existing comorbidities or the injury itself. We aimed to describe causes of death and causespecifc excess mortality through the frst year after hip fracture.<p> <p>Methods For studying the distribution of causes of death by time after hip fracture, we calculated age-adjusted cause-specifc mortality at 1, 3, 6 and 12 months in patients hospitalized with hip fracture in Norway 1999–2016. Underlying causes of death were obtained from the Norwegian Cause of Death Registry and grouped by the Euro‑ pean Shortlist for Causes of Death. For estimating excess mortality, we performed fexible parametric survival analyses comparing mortality hazard in patients with hip fracture (2002–2017) with that of age- and sex matched controls drawn from the Population and Housing Census 2001. <p>Results Of 146,132 Norwegians with a frst hip fracture, a total of 35,498 (24.3%) died within one year. By 30 days post-fracture, external causes (mainly the fall causing the fracture) were the underlying cause for 53.8% of deaths, fol‑ lowed by circulatory diseases (19.8%), neoplasms (9.4%), respiratory diseases (5.7%), mental and behavioural disorders (2.0%) and diseases of the nervous system (1.3%). By one-year post-fracture, external causes and circulatory diseases together accounted for approximately half of deaths (26.1% and 27.0%, respectively). In the period 2002–2017, causespecifc one-year relative mortality hazard in hip fracture patients vs. population controls ranged from 1.5 for circula‑ tory diseases to 2.5 for diseases of the nervous system in women, and correspondingly, from 2.4 to 5.3 in men. <p>Conclusions Hip fractures entail high excess mortality from all major causes of death. However, the traumatic injury of a hip fracture is the most frequently reported underlying cause of death among older patients who survive less than one year after their fracture.