Initial High-Frequency Amplification Accuracy Predicts Long-Term Hearing Aid Fitting Outcomes: A Real Ear Measurement-Based Study.

Background: To investigate whether the accuracy of initial hearing aid amplification verified by real ear measurement (REM) predicts long-term fitting outcomes after one year, and to identify frequency-specific predictors associated with sustained fitting precision. Methods: This retrospective study included 426 ears from 269 patients who underwent initial REM during hearing aid fitting and repeat REM at 9-15 months after fitting. The primary outcome was the absolute difference between real ear insertion gain (REIG) and target gain (TG) for middle-level input sounds at one-year follow-up. Multivariable linear regression analysis was performed to evaluate demographic, audiologic, and initial REM-related predictors. Results: At initial fitting, the discrepancy between REIG and TG increased progressively toward higher frequencies, with the largest deviation observed at 6000 Hz (16.2 ± 9.5 dB). Multivariable analysis demonstrated that initial REM discrepancy at 6000 Hz was the strongest predictor of poorer fitting accuracy at one year (B = 0.129, p < 0.001). Initial discrepancies at 250 Hz and 500 Hz were also significant but showed weaker associations. Higher aided pure-tone thresholds and poorer aided word recognition scores were independently associated with less accurate long-term fitting outcomes. Conclusions: Initial amplification accuracy, particularly at high frequencies, plays a critical role in long-term hearing aid fitting stability. Achieving sufficient gain at 6000 Hz during the first fitting session may improve long-term fitting outcomes and reduce suboptimal hearing aid use.