The Interrelationship of Tinnitus and Hearing Loss Secondary to Age, Noise Exposure, and Traumatic Brain Injury.
Level 3 - non-randomized controlled study
Non-randomized observational cohort and registry analysis using electronic health records and longitudinal hazard modeling.
PubMed 35612496 · doi:10.1097/AUD.0000000000001222
What was done
Researchers analyzed electronic health records, questionnaires, audiograms, and military service data from 758,005 participants in the Million Veteran Program (2011–2020). Relative risks (RR) for tinnitus and hearing loss were estimated across demographic variables, military eras, combat, and blast exposures. Audiogram thresholds across standard frequencies were compared between participants with and without tinnitus (adjusted for ISO 7029:2000E age/sex standards and stratified by age ≤40 vs. >40 years). Proportional hazards models assessed the temporal sequence and interval between the onset of tinnitus and hearing loss by ICD codes and self-report.
What was found
Tinnitus was self-reported, diagnosed, or both in 37.5% (95% CI, 37.4%–37.6%) of participants (mean age 61.5 years). Hearing loss was strongly associated with tinnitus (RR 4.15, 95% CI, 4.12–4.15). In multivariate modeling, elevated relative risk for tinnitus was observed for traumatic brain injury (RR 1.73, 95% CI, 1.71–1.73) and daily combat noise exposure (RR 1.17, 95% CI, 1.14–1.17), whereas age showed no increased risk (RR 0.998, 95% CI, 0.997–0.998). Lower risk was observed in Americans of African descent (RR 0.61, 95% CI, 0.60–0.61) and women (RR 0.65, 95% CI, 0.64–0.65). Subjects ≤40 years with tinnitus showed elevated hearing thresholds across all standard frequencies. In hazard models, participants >40 years with new-onset tinnitus developed hearing loss sooner and at higher incidence, with the rate of subsequent hearing loss approaching 100%.
Why it matters
This study demonstrates in a massive cohort that military tinnitus is primarily driven by mechanical and acoustic trauma rather than normal aging. It also shows that tinnitus affects all audiometric frequencies and frequently serves as an early indicator of impending hearing loss in adults over 40.
Limits
The study is restricted to US military veterans enrolled in the Million Veteran Program, which is predominantly older and male, limiting generalizability to civilian populations. Data partially relied on self-reported questionnaires and routine ICD coding, which are subject to recall bias and clinical coding variability.
Cited by
- supports Tinnitus or ringing in the ears frequently results from prior exposure to loud sounds or explosions that caused ear damage.