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Knowledge of risk factors for hip fracture among very old people is limited. Walking indoors with help from ≤1 person, Parkinson's disease, currently smoking, delirium in the previous month, underweight, and age were associated with increased risk of hip fracture and could be important for preventive strategy development.

INTRODUCTION: The purpose of this study is to investigate risk factors for hip fracture among a representative sample of very old people.

METHODS: In total, 953 participants from the Umeå 85+/Gerontological Regional Database population-based cohort study were interviewed and assessed during home visits. Associations of baseline characteristics with hip fracture during the maximum 5-year follow-up period were analyzed using Cox proportional hazards regression.

RESULTS: Participants had a mean age of 89.3 ± 4.7 years; 65.8 % were women, 36.8 % lived in residential care facilities, 33.6 % had dementia, and 20.4 % had histories of hip fracture. During a mean follow-up period of 2.7 years, 96 (10.1 %) individuals sustained hip fracture. Walking indoors with help from no more than one person (hazard ratio [HR] = 8.57; 95 % confidence interval [CI], 1.90-38.71), Parkinson's disease (HR = 5.12; 95 % CI, 1.82-14.44), currently smoking (HR = 4.38; 95 % CI 2.06-9.33), delirium in the previous month (HR = 2.01; 95 % CI, 1.15-3.49), underweight (body mass index <22; HR = 1.74, 95 % CI, 1.09-2.77), and age (HR = 1.09; 95 % CI, 1.04-1.14) were associated independently with an increased risk of hip fracture. Hip prosthesis at baseline decreased the risk of hip fracture (HR = 0.37; 95 % CI, 0.15-0.91), but only for those with bilateral hip prostheses.

CONCLUSIONS: Seven factors were associated independently with incident hip fracture during follow-up in this sample of very old people. These factors could have important clinical implications in identifying persons at high risk of hip fracture, as well as in the development of effective preventive strategies.