Causes of death and cause-specific excess mortality after hip fracture. The Norwegian Epidemiologic Osteoporosis Studies (NOREPOS)

Introduction: Hip fracture is a serious injury which affects older multimorbid patients and involves excess mortality. We aimed to describe leading causes of mortality through the first year after a hip fracture. Material and Methods: Hospital-treated hip fractures in Norway 1999-2016 were linked with age- and sex-matched population controls and the Norwegian Cause of Death Registry through 2017. Underlying causes of death were coded according to ICD-10 and grouped by the Eurostat shortlist. Results: Of 146,132 Norwegians with a first incident hip fracture, 35,498 (24.3%) died within one year. By 30 days post-fracture, external causes (usually the fall causing the fracture) were defined as the underlying cause for 53.8% of deaths, followed by circulatory diseases (19.8%), neoplasms (9.4%), respiratory diseases (5.7%), mental and behavioral disorders (2.0%) and diseases of the nervous system (1.3%). By one year post-fracture, external and circulatory causes together accounted for half of deaths (26.1% and 27.0%, respectively). For causes other than external causes, one-year relative mortality risks in hip fracture patients compared with population controls ranged from 1.5 for circulatory diseases to 2.5 for diseases of the nervous system in women. In men, the corresponding relative risks ranged from 2.4 for circulatory diseases to 5.3 for diseases of the nervous system. Conclusions: Hip fractures entail high excess mortality from all major causes of death. However, the traumatic injury of a hip fracture is the leading underlying cause of death the first year after the fracture, underlining the importance of preventing falls and fractures in older adults.