Outcomes of real-ear measurement-based fitting in unilateral hearing aid users: Influence of contralateral hearing

Real-ear measurement (REM) is commonly used to verify hearing aid fittings; however, its added benefit over non-REM fitting in unilateral users and the influence of contralateral ear hearing remain unclear. In this retrospective study, we compared short-term audiometric and patient-reported outcomes between an REM-based fitting pathway and a manufacturer-first-fit pathway followed by routine clinical fine-tuning in unilateral hearing-aid users, and examined associations with contralateral-ear hearing.

We retrospectively analyzed data from 105 unilateral hearing aid users with 3 months of follow-up (REM: n = 60; non-REM: n = 45). Baseline measures included pure-tone averages (PTA4) of the aided ear (i.e., the ear fitted with the hearing aid) and contralateral ear (i.e., the opposite ear), as well as the Hearing Handicap Inventory for the Elderly (HHIE). Outcomes included sound-field functional gain (ΔPTA4), achievement of ≥10 dB gain, change in HHIE (ΔHHIE; responder ≥18-point reduction), and the International Outcome Inventory for Hearing Aids (IOI-HA) scores at 3 months. Group comparisons were performed using non-parametric tests, and multivariable linear and logistic regression models were used to adjust for demographic and audiometric covariates. Associations between contralateral ear hearing and outcomes were examined using correlation and subgroup analyses.

Baseline characteristics were generally comparable between groups, although fitted side differed. At 3 months, mean functional gain was 11.0 ± 10.6 dB HL in the REM group and 9.1 ± 10.1 dB HL in the non-REM group (p = 0.2145). Mean ΔHHIE was 25.7 ± 30.3 and 32.9 ± 28.6 points (p = 0.1680), and mean IOI-HA scores were 24.4 ± 6.7 and 23.9 ± 5.9, respectively (p = 0.9492). In adjusted analyses, the REM-based fitting pathway was not associated with ΔHHIE (β = 1.97; 95% CI, -3.12 to 7.06) or 3-month IOI-HA score (β = 0.32; 95% CI, -2.23 to 2.86). Worse contralateral-ear PTA4 was associated with greater HHIE improvement (r = 0.389, p < 0.001).

In this retrospective cohort of unilateral hearing-aid users, an REM-based fitting pathway was not associated with statistically significant 3-month audiometric or patient-reported outcome differences compared with manufacturer first-fit followed by routine fine-tuning; this does not establish equivalence or isolate the effect of REM. Contralateral-ear hearing was associated with perceived handicap improvement and may be relevant to outcome interpretation and counseling.