Complementation of Disability Rating System on Hearing Injury: Application of Linear Regression Analysis

Byun, Sung Wan; Shin, Seung Ho; Kim, So Jeong; Park, Jee Soo

Abstract

BACKGROUND AND OBJECTIVES
According to the correlation between hearing injury and McBride disability rating presented by previous studies, there are over/underestimated cases particularly in the 40 dB hearing range compared to other ranges. In this study, we reviewed the overestimated and underestimated data and propose a complementation scheme for a disability rating system by using the linear regression analysis.
SUBJECTS AND METHOD
For the past 14 years, we have provided legal advisory for 121 cases of hearing injury, for which disability had to be rated. We reviewed all but excluded 11 cases for the aggravation of disability. A regression equation was produced from a linear regression analysis that used the percent of hearing handicap (AAO-HNS/AMA-1979 formula) as an independent variable (x) and McBride disability rating (%) as a dependent variable (y), following the Pearson correlation test. Iterative calculation was performed for overestimated (18) and underestimated (8) cases.
RESULTS
Appropriate disability ratings were 14% for the cases overestimated to 20% and 11% for those underestimated to 5%. Appropriate disability ratings for the 20% of overestimated cases were changed to 14%, and for the 5% of the underestimated cases, the disability ratinb 11%. Iterative calculation showed that the Pearson correlation index was improved from 0.8866 to 0.9065 and the determination coefficient of regression analysis (adjusted R-square) was improved from 0.784 to 0.8202.
CONCLUSION
The common range of hearing injury, which falls between 30-40 dB corresponds to the percentage of hearing handicap of 7.5-22.5%. A fairer assessment of ability rating would be possible by complementing some parts of this hearing range.