Conditional Minimal Detectable Change for the Cochlear Implant Quality of Life-35 Profile Associated With Improved Functional Abilities 12 Months After Cochlear Implantation

IMPORTANCE It is essential to measure an individual patient's baseline and follow-up abilities to demonstrate changes in clinical outcomes over time. Inherent in this strategy is interpreting whether the measured change is clinically significant and beyond measurement error. Conditional minimal detectable change (cMDC) values are widely used in many disciplines but have rarely been established for outcome measures in otolaryngology or hearing research, and never in cochlear implantation. OBJECTIVE To determine cMDC values for the Cochlear Implant Quality of Life-35 (CIQOL-35) Profile instrument to enhance our understanding of the initial and ongoing changes in functional abilities from cochlear implants (CIs). DESIGN, SETTING, AND PARTICIPANTS Item response theory analyses of responses from a multi-institutional cohort of 705 CI users at a tertiary CI center were used to derive standard error (SE) values for each possible CIQOL-35 domain score. Using an iterative approach, these SE values were used to calculate cMDC values for every possible pre-CI and post-CI domain score combination. We then compared pre-CI to 12-month post-CI CIQOL-35 domains scores in an independent cohort of 65 adult CI users to determine whether the measured change exceeded error to be clinically significant. The analysis took place on December 14, 2022. INTERVENTIONS The CIQOL-35 Profile instrument and cochlear implantation. RESULTS The cMDC values were smaller for the communication domain, and global measure and cMDC values for all domains were larger at the extremes of the measurement scale. Overall, 60 CI users (92.3%) demonstrated improvement beyond cMDC at 12 months post-CI for at least 1 CIQOL-35 domain, and no patients' scores declined beyond cMDC for any domain. The percentage of CI users demonstrating improvement beyond cMDC varied by domain, with communication (53 [81.5%]) showing the largest number of CI users improving, followed by global (42 [64.6%]) and entertainment (40 [60.9%]). In general, CI users who demonstrated improvement in CIQOL-35 domains had greater improvement in speech recognition scores than patients who did not, but the strength and significance of these associations greatly varied by domain and speech material. CONCLUSIONS AND RELEVANCE This multistep cohort study found that cMDC values for the CIQOL-35 Profile provided personalized thresholds for detecting real changes in patient self-reported functional abilities over time across multiple domains, which may inform clinical decision-making. Moreover, these longitudinal results reveal the domains with more or less improvement, which may aid in patient counseling.