Traumatic brain injury and hearing loss among older Medicare beneficiaries

Traumatic brain injury (TBI) is a common fall-related injury among older adults.1 TBI results in significant disability among older adults.2 Multiple studies have observed an association between TBI and hearing loss or auditory dysfunction, but few have examined older adults specifcally.3, 4 The association between TBI and increased risk for Alzheimer's disease and related dementias (ADRD) is well documented, although mechanisms underlying this association are not well understood.5 One underexplored mechanism may be hearing loss, a modifiable risk factor for ADRD that is also commonly observed after TBI.3 Older individuals with hearing loss are 40% more likely to develop ADRD.6 Given the limited understanding of hearing loss following TBI among older adults, known associations with ADRD, and the value patients place on maintaining hearing function throughout the lifespan, the objective of the present study was to evaluate the incidence of new hearing loss diagnosis following TBI among older adults and secondarily to identify patient characteristics associated with new hearing loss diagnosis. We conducted a retrospective cohort study using Medicare administrative claims data obtained from the Center for Medicaid and Medicare Services Chronic Conditions Warehouse. Administrative claims from a 5% random sample for years 2010–2016 and a 20% random sample for years 2017–2018 were used for analysis. Community-dwelling Medicare beneficiaries aged 65 and older hospitalized with a TBI between 2010 and 2017 were eligible for the study. TBI was defined using the Centers for Disease Control and Prevention International Classification of Disease version 9 and version 10 surveillance codes on inpatient claims in the primary position and the date of TBI was assigned as the index date.1 Hearing loss was defined based on prior work using ICD-9 and ICD-10 codes for problems with hearing, presbycusis, hearing loss, sensorineural hearing loss, and mixed conductive and sensorineural hearing loss (Supplemental Table S1).7 We excluded individuals with hearing loss diagnosis during the 6 months prior to TBI from analyses. We calculated follow-up from the date of TBI to the date of hearing loss diagnosis, death, or end of study period (i.e., 365 days), whichever came first. We divided the number of new hearing loss diagnoses (up to one diagnosis per beneficiary was counted) by the total follow-up time, and calculated 95% confidence intervals using standard methods for rates. To identify factors associated with new hearing loss diagnosis following TBI, we used Cox proportional hazards models. We modeled time to new hearing loss diagnosis in the presence of death as a competing risk given significant censoring post-TBI using backwards selection. This study was determined to be exempt from review by the Institutional Review Board at the University of Maryland School of Medicine. Of 18,138 beneficiaries meeting study criteria, 2030 (11.2%) were newly diagnosed with hearing loss (Table 1). Incidence of new hearing loss diagnosis over the year post-TBI was 14.1 (95% confidence interval (CI) 13.5, 14.8) per 100 person-years. Relative to men, women were less likely to receive a new diagnosis of hearing impairment post-TBI (hazard ratio (HR) 0.74; 95% CI 0.67, 0.81) (Figure 1 and Supplementary Table S2). Several comorbidities (e.g., depression, hyperlipidemia) were associated with increased likelihood of new hearing loss diagnosis while ADRD was associated with decreased diagnosis of hearing loss (HR 0.74; 95% CI 0.67, 0.81). Relative to beneficiaries who are White, those who are Black were less likely to receive a diagnosis of hearing loss (HR 0.71; 95% CI 0.55, 0.91). Among older Medicare beneficiaries hospitalized with TBI, incidence of new hearing loss diagnosis was 14.1/100 person-years. Prevalence of any hearing loss based on objective auditory assessments has been reported to range from 35%–73% among adults aged 65 and older, with 10%–36% experiencing moderate–severe hearing loss.8 These numbers suggest that the true number of older adults with new hearing loss post-TBI is likely higher than reported here.3 Individuals less likely to receive a hearing loss diagnosis following TBI were those who were younger, female, and Black. These findings are consistent with objective audiometric assessments conducted in the National Health and Aging Trends Study and the National Health and Nutrition Examination Survey.8 Diagnosis of ADRD was associated with decreased likelihood of a hearing loss diagnosis. This finding may represent a disparity in receipt of adequate care among older adults with ADRD,9 particularly those who experience TBI. Importantly, hearing loss is increasingly recognized as a target for strategies to reduce risk for dementia and improve clinical outcome among those with ADRD.10 For older adults with TBI, screening for and treating hearing loss may represent an important avenue for ADRD risk reduction. In this population of older adults hospitalized with TBI, incidence of new hearing loss diagnosis was 14%. Hearing loss post-TBI may represent a target for future research aimed at reducing risk for ADRD. JSA: study concept and design, analysis and interpretation of data, and preparation of manuscript. DSP: study concept and design, interpretation of data, and preparation of manuscript. KR: acquisition of data, preparation of manuscript. JRF: study concept and design, acquisition and interpretation of data, and preparation of manuscript. We acknowledge the support of the University of Maryland, Baltimore, Institute for Clinical & Translational Research and the National Center for Advancing Translational Sciences Clinical Translational Science Award grant number 1UL1TR003098 in helping secure Medicare data and providing support for analysis. Dr. Albrecht was supported by National Institute on Aging grant R01AG076441. Dr. Falvey was supported during the work by the National Institute on Aging and the Maryland Claude D. Pepper Center (grant numbers K76AG074926 and P30AG028747). No competing interests exist. None. Table S1. International Classification of Disease, versions 9 (ICD-9) and 10 (ICD-10), codes for hearing loss. Table S2. Independent predictors of incident diagnosis of hearing loss following traumatic brain injury (TBI) with death as competing risk, n = 18,138. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.