Sensorineural hearing loss incidence among U.S. military aviators between 1997 and 2011

Noise-induced hearing loss is the most common cause of sensorineural hearing loss (SNHL) in military aviation. Few published studies compare SNHL rates between fixed and rotary-wing military pilots. The study's objective was to determine whether a difference in mean annual SNHL incidence rate exists between fixed and rotary wing aviators in the U.S. Army, Navy, Air Force, and Marines.

SNHL rates (new cases annually/1000 persons-per-year) for U.S. military aviators from 1997-2011 were extracted from the Defense Medical Epidemiology Database (DMED). ANOVA was conducted for mean annual SNHL incidence rate differences and for interaction effects between aircraft type, fixed or rotary-wing, and service branch.

A total of 467,064 person-years were analyzed. A main effect existed for aircraft type, such that the mean annual rate of SNHL was higher for fixed (M = 15.8, SD = 10.2) than for rotary-wing aviators (M = 8.7, SD = 5.0, RR = 1.8). Service branch main effect was significant, such that the mean SNHL rates were greater for the Army (M = 19.6, SD =11.2) and Air Force (M = 14.7, SD = 11.2) than for the Navy (M = 7.2, SD = 3.9) and Marines (M = 7.3, SD = 3.6). The interaction effect was significant, indicating that the within branch differences in SNHL rate between fixed and rotary-wing aviators is greater in the Army and Air Force than in the Navy and Marines.

The average annual incidence rate of SNHL between 1997-2011 was higher for fixed than for rotary-wing aviators, and higher for U.S. Army and Air Force than Navy and Marine aviators. An examination of hearing conservation programs and engineering controls may be warranted.