Lower-Body Fractures and the Risk of Dementia: A Nationwide Population-Based Study

Abstract

Background and purpose: The association between physical activity and dementia has been shown in various observational studies. We aimed to determine the risk of dementia in the elderly with lower-body fractures.

Methods: We reconstructed a population-based matched cohort from the National Health Insurance Service-Senior Cohort data set that covers 511,953 recipients of medical insurance in South Korea.

Results: Overall 53,776 subjects with lower-body fractures were identified during 2006-2012, and triplicate control groups were matched randomly by sex, age, and years from the index date for each subject with a fracture. There were 3,573 subjects (6.6%) with and 7,987 subjects (4.9%) without lower-body fractures who developed dementia from 2008 up to 2015. Lower-body fractures were independently associated with a subsequent dementia diagnosis with a higher adjusted hazard ratio (aHR) (1.55, 95% confidence interval [CI]=1.49-1.62) compared with upper-body fractures (aHR=1.19, 95% CI=1.14-1.23).

Conclusions: These results support the protective role of physical activity against dementia and highlight the importance of promoting fracture prevention in the elderly.

Keywords: dementia; elderly; fracture; lower-body fracture; physical activity.

Fig. 1. Study cohort. NHIS, National Health Insurance Service; TBI, traumatic brain injury.

Fig. 2. Kaplan-Meier curves with log-rank p-values showing the survival time for the diagnosis of dementia among lower-body fracture group (n=53,776) and control group without lower-body fractures (n=161,328). Subjects from 2006 to 2012 were followed-up until 2015, the end date of the National Health Insurance Service-Senior Cohort database. We considered the dementia only diagnosed two or more years after the fracture as an outcome to exclude the possibility of reverse causality between fracture and dementia.