Use of comparison populations for evaluating the effectiveness of hearing loss prevention programs

One approach for evaluating the effectiveness of Hearing loss prevention pr ograms (HLPPs) is to compare the rate of hearing loss in a study population with that in a reference population. This approach was used to evaluate th e HLPP of a population of 14,900 employees of an industrial company with br anches across the United States. Three reference populations were selected from a database of 22 industrial companies compiled under the sponsorship o f the National Institute for Occupational Safety and Health. The risk of he aring loss in the study population was estimated relative to each of the th ree reference populations using the Cox proportional hazards model after ad justment for race, age at baseline, and hearing threshold at time of enroll ment in the HLPP. In comparison with the three reference populations, heari ng loss was 2.1 to 3.9 times more likely to occur in study population males and 1.8 to 5.1 times more likely in study population females. The 95% conf idence interval around each risk estimate precluded unity, indicating that each risk estimate was statistically significant. These results indicate th at the performance of the subject HLPP needs improvement. This study demons trated the use of comparison populations for evaluating the effectiveness o f HLPPs.