Estimated Incidence and Prevalence of Asymmetric and Unilateral Sensorineural Hearing Loss in United States Military...

The purpose of this study was to estimate the incidence and prevalence of asymmetric sensorineural (ASNHL) and unilateral sensorineural hearing loss (USNHL) among the U.S. active duty population from fiscal years 2003 to 2015. Historical estimates of ASNHL and USNHL incidence and prevalence in the general population vary greatly depending on the criteria used and the population studied. Estimates among the entire U.S. military population are unknown.

This was a retrospective, observational epidemiology and health-services study using secondary administrative data to estimate longitudinal incidence and prevalence of ASNHL and USNHL among active duty U.S. military personnel. Cases were identified by ICD-9 diagnostic codes recorded in Department of War (DOW) electronic medical record systems.

Excluding unspecified sensorineural hearing loss (UnspSNHL, 389.1 or 389.10), annual rates of ASNHL and USNHL incidence ranged from .074/100,000 person-years (PY) to 565.8/100,000 PY from October 1, 2005 to September 30, 2015. Analogous prevalence rates were .001% to 24.9%. Including UnspSNHL, annual incidence rates of ASNHL and USNHL were 806.4/100,000 PY to 832.6/100,000 PY over the same period, and prevalence rates were 34.2% to 57.9%. Following the introduction of laterality codes, the maximum estimate of ASNHL and USNHL (including UnspSNHL) increased by 14% from 2006 to 2007, by 1.8% from 2008 to 2012, when it reached a maximum of 991.0/100,000 PY, then gradually declined 7.3% to 832/100,000 PY through the end of 2015. Excluding UnspSNHL, ASNHL and USNHL incidence increased from 0.07/100,000 PY in 2006 to 218/100,000 PY in 2009, then continued to rise at a lower rate from 2009 to 2015 (351/100,000 PY-566/100,000 PY). From 2010 to 2015, the maximum estimate of ASNHL and USNHL (including UnspSNHL) decreased from 969/100,000 PY to 833/100,000 PY, while the minimum estimate (excluding UnspSNHL) increased from 351/100,000 PY to 566/100,000 PY, likely indicating both a real increase in the incidence of ASNHL and USNHL as well as a continued decrease in miscoding rates during those years. Higher incidence and prevalence were found among men, among the Army and Marine Corps personnel, and among the oldest age groups.

Service branch, age, and sex differences were observed for ASNHL and USNHL incidence and prevalence. These are the first analyses to quantify the incidence and prevalence rates of ASNHL and USNHL spanning a considerable portion of the Global War on Terrorism (GWOT). It is recommended that future research use imaging and audiometric data to evaluate the relationship between ASNHL and USNHL ICD codes and the clinical evidence associated with them, such as pure tone air conduction and bone thresholds, retrocochlear pathology (e.g., vestibular schwannoma), and noise-induced hearing damage to develop disease-specific audiometric screening criteria.