Distribution of hearing loss characteristics in a clinical population

This study was designed to characterize a large database of audiometric records from an academic health center Audiology clinic for the purpose of determining the distributions of hearing loss configuration, severity, and site of lesion.

: Using AMCLASS, a validated tool for classifying audiograms described in a previous report, the audiometric configuration, severity, and site of lesion was determined for patients grouped according to the completeness of the audiometric record. Complete air conduction testing at six octave frequencies in both ears was required for inclusion. Patients were grouped according to the quantity of bone conduction thresholds in the record: both ears tested, one ear tested, or neither ear tested. All other records were discarded leaving 23,798 records of 16,818 patients for analysis. All analyses were conducted for all remaining records and with repeat tests excluded.

The effect of removing repeat audiograms had remarkably little effect on the distributions. Sloping hearing losses dominated the distributions of configuration. One-third of all records indicated normal hearing in at least one ear and one fourth had normal hearing in both ears. Mild and moderate hearing losses were equally prevalent, each contributing 40% to 45% of the cases with hearing loss. Sensorineural was the most prevalent site of lesion, representing about 45% of cases and just over half the cases with hearing loss.

Prevalence rates of hearing loss configurations, severities, and sites of lesion are provided against which analyses of other databases can be compared. The results may be useful for counseling patients regarding the relationship of their hearing loss to that of a large population. The high number normal-hearing people in the database suggests that estimates of the need for hearing testing based on prevalence of hearing loss may underestimate the number of people who seek or are referred for hearing evaluation.