Prevalence of Unilateral, Asymmetric, and Bilateral Tinnitus in Military Personnel and Its Impact on Disability.

Objective: This study aims to describe the prevalence of unilateral, asymmetric, and bilateral tinnitus by severity of tinnitus across hearing sensitivity within the Noise Outcomes In Service members Epidemiology (NOISE) Study cohort.

Study design: A cross-sectional study.

Setting: Multi-institutional tertiary referral centers.

Methods: Behavioral audiometric testing, tinnitus history, and tinnitus severity were described cross-sectionally. Tinnitus severity was assessed by the Tinnitus Functional Index (TFI). The WHO Disability Assessment Schedule (WHODAS) 2.0 was used to capture functional deficits.

Results: Tinnitus prevalence within the NOISE cohort was 46% (644/1387). Among those with tinnitus, the mean age was 36.1 years (standard deviation = 9.7), and 86% (553/644) were male, reflecting the predominantly male composition of the overall study population. The majority (85%) had normal hearing, and the remaining (15%) had mild-to-moderate sensorineural hearing loss. Bilateral tinnitus was the most prevalent (54%), followed by asymmetric (35%) and unilateral (11%). Severe tinnitus was reported in 24%, moderate in 38%, and no/mild in 38%. Compared to those with normal hearing, subjects with mild-to-moderate hearing loss had a higher prevalence of tinnitus (odds ratio (OR) = 2.4, 95% confidence interval [CI]: 1.6-3.7), higher TFI scores (mean difference = 14.1, 95% CI: 9.4-18.7), and a higher proportion reporting severe versus mild tinnitus (OR = 3.7, 95% CI: 2.0-6.9). In individuals with mild-to-moderate hearing loss, the highest TFI and WHODAS scores were associated with bilateral tinnitus (49.0 and 28.2, respectively).

Conclusion: Tinnitus is prevalent in people with military service history, both in those with and without sensorineural hearing loss. However, tinnitus had a greater impact on daily functioning among those with sensorineural hearing loss.