The AMA method of estimation of hearing disability: a validation study.

OBJECTIVE

To test the assumptions of the 1979 American Medical Association (AMA) method for estimation of hearing disability.

DESIGN

One thousand and one patients attending five regional audiology centers competed conventional audiometric testing and the Communication Profile for the Hearing Impaired. A Communication Performance (CP) score calculated from scales of the Communication Profile for the Hearing Impaired served as the gold standard for self-assessed hearing disability. Pure-tone thresholds and word recognition scores (WRSs), and combinations thereof, were compared with the CP scores using correlation and multiple regression analysis.

RESULTS

Several different better-ear pure-tone averages (PTAs) correlated reasonably well with self-assessed CP; none were significantly better than the 0.5, 1, 2, and 3 kHz PTA used in the current AMA method. Better-ear to worse-ear weights ranging from 3:1 to 9:1 performed similarly, but none were better than the AMA better-ear weight of 5:1. The AMA method assumes no disability below 25 dB HL and linear growth of disability above this "low fence"; this study showed a similar relationship between PTA and self-assessed hearing disability. There were too few subjects with severe and profound speech-frequency losses to permit validation of the AMA "high fence" of 92 dB HL. Combining pure-tone thresholds and WRSs improved prediction of hearing disability only very slightly.

CONCLUSIONS

This study supports the continued use of the 1979 AMA method. Incorporation of WRSs, as typically measured clinically, into methods of estimating hearing disability is not supported because of negligible improvement in accuracy and inability to control exaggeration for speech tests in medical-legal settings.