Cognition and the risk of hospitalization for serious falls in the elderly: results from the Cardiovascular Health Study.

BACKGROUND: Many elderly adults fall every year, sometimes resulting in serious injury and hospitalization. Although impaired cognition is a risk factor for injurious falls, little is known about cognitive decline above the threshold of impairment and risk of serious falls in community-dwelling seniors.
METHODS: In total, 702 of 5,356 older adults participating in the Cardiovascular Health Study experienced an injurious fall between 1990 and 2005, as indicated by hospitalization records. General cognition was measured annually with the Modified Mini-Mental State Examination and processing speed with the Digit Symbol Substitution Test. The Cox regression model was used to calculate hazard ratio and 95% confidence interval with and without time-dependent covariates and adjusted for known risk factors.
RESULTS: Participants with slightly decreased Digit Symbol Substitution Test scores were at increased risk for a serious fall (hazard ratio = 1.58, 95% confidence interval = 1.15-2.17). The risk continued to increase with each quartile decrease in Digit Symbol Substitution Test score. Participants without prevalent cardiovascular disease at baseline and decreased Modified Mini-Mental State Examination scores (80-89) had a 45% increased risk for a serious fall and those at high risk for dementia (<80) were at twice the risk as participants scoring above 90 (hazard ratio = 2.16, 95% confidence interval = 1.60-2.91).
CONCLUSIONS: Both decreased general cognition and decreased processing speed appear to be potential risk factors for serious falls in the elderly. When assessing the risk of serious falls in elderly patients, clinicians should consider usual factors like gait instability and sensory impairment as well as less obvious ones such as cardiovascular disease and cognitive function in nondemented adults.