Measurement properties and clinical interpretability of a Japanese-language version of the remote check system in cochlear implant users

OBJECTIVE: To evaluate the measurement properties and clinical interpretability of the Japanese-language version of Cochlear™ Remote Check (J-RC) in cochlear implant (CI) users aged 15 years or older, including comparability with conventional hospital-based assessments, test-retest reliability, reproducibility across administration conditions, and factors affecting test completion and result interpretability. METHODS: In this prospective single-center cohort study, 37 Japanese-speaking CI recipients (47 ears) using a Remote Check-compatible Cochlear™ sound processor were enrolled. Participants underwent conventional hospital-based (HP) assessments and J-RC testing during two in-hospital visits, with one additional J-RC session performed in a non-hospital setting between visits. Outcome measures included comparability of J-RC impedance, aided thresholds, and Digit Triplet Test (DTT) results with conventional HP assessments; test-retest reliability across repeated J-RC sessions; reproducibility across administration conditions; and factors associated with inability to complete J-RC testing or reduced clinical interpretability of results. RESULTS: Impedance was the most robust J-RC measure. Open- and short-circuit electrodes were identified identically by J-RC and HP testing, and pooled electrode-specific impedance values showed excellent agreement between J-RC and HP testing and across repeated J-RC sessions (all R² > 0.95). J-RC aided thresholds were consistently 10-15 dB lower than HP sound-field thresholds across frequencies but showed reasonably good test-retest reliability. The Japanese DTT was clinically informative but less feasible: failure to complete testing occurred in a substantial proportion of ears and was strongly associated with poorer CI-aided monosyllabic speech discrimination in quiet. Among ears that completed testing, better DTT results were associated with better monosyllabic speech discrimination scores, and the test-retest reliability across repeated J-RC sessions was good. J-RC outcomes obtained in hospital and non-hospital settings were significantly associated across impedance, aided thresholds, and DTT, supporting overall reproducibility across administration conditions. CONCLUSION: J-RC provided clinically meaningful remote measures for Japanese CI users, with particularly strong performance for impedance and more conditional utility for aided thresholds and DTT. These findings support the potential role of J-RC as a quantitative adjunct to conventional in-hospital assessment for longitudinal monitoring, triage, and selected remote mapping workflows.