Incident hip fractures among community dwelling persons with Alzheimer's disease in a Finnish nationwide register-based cohort.

BACKGROUND: Previous cohort studies have shown that persons with Alzheimer's disease (AD) have a higher risk of hip fractures but recent data from large representative cohorts is scarce.

METHODS: We investigated the association between AD and prevalent and incident hip fractures in an exposure-matched cohort study conducted in Finland 2002-2009 (the Medication and Alzheimer's disease in 2005 study; MEDALZ-2005). The study population included all community-dwelling persons with verified AD diagnosis in Finland on December 31, 2005 and one matched comparison person per AD case (N = 56,186, mean age 79.9 (SD 6.8) years, range 42-101 years). The diagnosis of AD was extracted from a special reimbursement register. Data on hip fractures during 2002-2009 was extracted from the Finnish National hospital discharge register. Analyses of incident hip fractures (n = 2,861) were restricted to years 2006-2009.

RESULTS: Persons with AD were twice as likely to have previous hip fracture in 2005 (odds ratio, 95% confidence interval 2.00, 1.82-2.20) than matched aged population without AD. They were also more likely to experience incident hip fracture during the four-year follow-up (hazard ratio, 95% confidence interval 2.57, 2.32-2.84, adjusted for health status, psychotropic drug and bisphosphonate use). The AD-associated risk increase decreased linearly across age groups. Although people with AD had higher risk of hip fractures regardless of sex, the risk increase was larger in men than women.

CONCLUSION: Findings from our nationwide study are in line with previous studies showing that persons with AD, regardless of sex or age, have higher risk of hip fracture in comparison to general population. Although there was some suggestion of effect modification by age or sex, AD was consistently associated with doubling of the risk of incident hip fracture.