Traumatic Brain Injury in Older Adults: A Descriptive & Etiologic Analysis

Abstract

A two-part study was undertaken to determine the characteristics and incidence of older adults who sustained a traumatic brain injury (TBI) while in Ontario home care from 2003 to 2013, and to determine the association between depression and sustaining a TBI. Both parts used data from the Ontario Association of Community Care Access Center’s database. Data were retrieved for all service users 65 years or older who had home care between 2003 and 2013; these data are based on the Resident Assessment Instrument-Home Care. The variables used in the analyses included: TBI, depression, demographics, neurological conditions and history of falling. For the descriptive component, comparisons of characteristics were made between service users who did and did not sustain a TBI using odds ratios (OR). The ten-year trend of annual cumulative incidence and standardized incidence rates were assessed using regression. For the etiologic component, incident TBI cases were matched to four controls by age, sex and date of assessment. Crude OR’s were determined for the association between depression and TBI. Multivariable conditional logistic regression was used to adjust for potential confounders and identify effect modifiers. Multivariable estimates were stratified by history of falling. A total of 554,313 service users were included, of which 5215 (0.9%) had a TBI and 39,048 (7.0%) had depression. Characteristics associated with TBI were: male sex (OR: 1.54, 95% CI: 1.45, 1.62), aboriginal origin (OR: 1.98; 95% CI: 1.57, 2.50), increasing age (OR: 1.22, 95% CI: 1.09, 1.35 for 70-74; up to OR: 2.31, 95% CI: 2.05, 2.59 for >90; referent group 65-69), being widowed (OR: 1.59, 95% CI: 1.41, 1.80), having a history of one or more falls (OR: 2.31, 95% CI: 2.19, 2.44), the use of antidepressants (OR: 1.49, 95% CI: 1.40, 1.59) and the presence of depression (OR: 1.57, 95% CI: 1.43, 1.71), dementia (OR: 1.65, 95% CI: 1.54, 1.76), hemiplegia (OR: 4.34, 95% CI: 3.88, 4.85), multiple sclerosis (OR: 3.19, 95% CI: 2.49, 4.08) and parkinsonism (OR: 1.22, 95% CI: 1.07, 1.38). Incidence was significantly higher than previously reported figures in the general population. There was a decrease in the annual cumulative incidence over the ten-year period. Female standardized rates decreased significantly (p<0.05) in a linear fashion while male and overall decreased in a non-linear fashion. The crude OR for the association between depression and TBI was 1.54 (95% CI: 1.43, 1.64). Stratified analyses indicated that the association was significantly different for those with a history of falling (OR: 1.45, 95% CI: 1.22, 1.73) and those without a history of falling (OR: 1.19, 95% CI: 0.99, 1.42). Multivariable analysis suggested that there were three significant effect modifiers for the exposure: history of falling, level of education and Alzheimer’s. As the level of education increased, the association between depression and TBI became smaller (OR: 1.88, 95% CI: 1.30, 2.70 for 8th grade or less compared to OR: 1.11, 95% CI: 0.78, 1.65 for graduate degree). Service users with a TBI had greater odds of having a history of falling (OR: 1.45, 95% CI: 1.22, 1.73) and being diagnosed with Alzheimer’s Disease (OR: 1.18, 95% CI: 1.05, 1.32). Longitudinal studies are needed to confirm this finding, as our study was cross-sectional in nature, and to investigate the association between other chronic conditions and TBI.