Reporting operative hearing results in stapes surgery: does choice of outcome measure make a difference?

In a prior study, findings indicated that when reporting results of chronic ear surgery, neither choice of pre-versus postoperative bone-conduction scores nor choice of frequencies to include a averaging makes a substantial difference in reported outcome. In this study, audiologic data from 240 stapes-surgery patients at three different institutions were used to generate a variety of outcome measures. Use of preoperative rather than postoperative bone-conduction values in computing postoperative air-bone gap resulted in an approximately 5-dB smaller mean gap and a 2% higher success rate. Frequencies included in averaging made little difference in mean computed air-bone gap, although success rate (gap < 10 dB) was lower by 6% when 4 kHz was used in a four-frequency average rather than 3 kHz. Results for air conduction were similar to those for air-bone gap regarding choice of frequencies to include in averaging. When using air-conduction pure-tone average (PTA) as the outcome measure, those with normal preoperative sensorineural hearing had a > 20% higher success rate than the general population of stapes-surgery patients. The greatest differences in success rate were based on definition of and criteria for success. Success rate was higher when based on air-bone gap than when based on air-conduction PTA. As in the prior chronic ear study, differences in outcome were more drastically affected by criteria for "success" than by frequencies included. Unlike similar data from chronic ear surgery, however, success rate differed depending on choice of air-bone gap or air-conduction PTA as the definition for success. Further, air and bone scores from the same test interval must be used to accurately reflect air-bone gap in stapes surgery.