Choice of outcome measure methods affects reported results in stapes surgery. Data from the Swedish quality register for otosclerosis surgery.

Purpose: To investigate differences in stapes surgery outcome when using different calculation methods.

Methods: Audiometric data were retrieved from the Swedish Quality Register for Otosclerosis Surgery for 3159 surgeries conducted during 2013-2024 with complete pre- and postoperative pure tone audiometry measurements of 0.5, 1, 2, 3, and 4 kHz. Outcomes were calculated in two ways: using 3 kHz versus 4 kHz in four-frequency averaging of air conduction, bone conduction, air-bone gap, and gain.

Results: Postoperative air-bone gap improved from 10.0 dB to 7.6 dB when using 3 kHz instead of 4 kHz, and the proportion of successful cases (defined as a postoperative air-bone gap ≤ 10 dB) increased from 62.9% to 79.0%. When 3 kHz was replaced by averaging 2 and 4 kHz, a significantly larger four-frequency air-bone gap was seen in comparison to using the measured 3 kHz.

Conclusion: This study showed a significant impact on postoperative four-frequency air-bone gap depending on whether the frequency 3 kHz or 4 kHz was included in averaging. The effect appears to be larger than previously described. Bone conduction measurements at 4 kHz produced an anomalous and too low measured hearing level, resulting in a disproportionate impact of the 4 kHz frequency on postoperative four-frequency air-bone gap. Comparison of study results that use different calculation methods should therefore be done with caution. We advocate using the methods recommended by the Committee on Hearing and Equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery for uniformity in presentation of results.