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

One approach for evaluating the effectiveness of Hearing loss prevention programs (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 the HLPP of a population of 14,900 employees of an industrial company with branches across the United States. Three reference populations were selected from a database of 22 industrial companies compiled under the sponsorship of the National Institute for Occupational Safety and Health. The risk of hearing loss in the study population was estimated relative to each of the three reference populations using the Cox proportional hazards model after adjustment for race, age at baseline, and hearing threshold at time of enrollment in the HLPP. In comparison with the three reference populations, hearing 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% confidence interval around each risk estimate precluded unity, indicating that each risk estimate was statistically significant. These results indicate that the performance of the subject HLPP needs improvement. This study demonstrated the use of comparison populations for evaluating the effectiveness of HLPPs.