Gender differences in the incidence of and risk factors for hip fracture: A 16-year longitudinal study in a southern European population.

OBJECTIVES: To analyze independently in men and women the incidence rate of and risk factors for hip fracture in a southern European population. Illiteracy, dementia, clinically significant depression and disability were factors to receive special emphasis.

STUDY DESIGN: A community sample of 4803 individuals aged over 55 years was assessed in a two-phase case-finding study in Zaragoza, Spain, and was followed up for 16 years. Medical history and psychiatric history were collected with standardized instruments, including the History and Aetiology Schedule, the Geriatric Mental State (GMS) scale, and a Risk Factors Questionnaire. Operational criteria were used to define covariates, including diagnostic criteria for both dementia and depression. The statistical analysis included calculations of incidence rate, IR; women/men incidence rate ratio (IRR); and Hazard Ratios (HR) in multivariate Cox proportional hazards regression models.

MAIN OUTCOME MEASURES: Cases of hip fracture (International Classification of Diseases, WHO) identified in the treating hospitals, validated by blinded researchers.

RESULTS: Hip fractures were more frequent among women than men (IRR=3.1). Illiteracy (HR=1.55) and depression (HR=1.44) increased the risk in women, and smoking (HR=2.13) and disability in basic activities of daily living (HR=3.14) increased the risk in men. Dementia was associated with an increased risk in an univariate analysis, but the association disappeared (power=85% in men, 95% in women) when disability was included in the multivariate models.

CONCLUSIONS: The IR of hip fractures was three times higher among women. Illiteracy and clinically significant depression among women and active smoking and disability (HR=3.14) among men independently increased the risk, but dementia did not.