Validity and reliability of the Cochlear Implant Quality of Life (CIQOL)-35 Profile and CIQOL-10 Global instruments in comparison to legacy instruments
Authors: McRackan Theodore R. , Hand Brittany N. ,   Cochlear Implant Quality of Life Consortium, Velozo Craig A. , Dubno Judy R. 
Published: March 2021

Objective:
Validated and reliable patient-reported outcome measures (PROMs) may provide a comprehensive and accurate assessment of the real-world experiences of cochlear implant (CI) users and complement information obtained from speech recognition outcomes. To address this unmet clinical need, the Cochlear Implant Quality of Life (CIQOL)-35 Profile instrument and CIQOL-10 Global measure were developed according to the Patient-Reported Outcomes Information System (PROMIS) and COnsensus-based Standards for the Selection of health status Measurement INstruments (COSMIN) guidelines. The CIQOL-35 Profile consists of 35 items in six domain constructs (communication, emotional, entertainment, environment, listening effort, and social) and the CIQOL-10 Global contains 10 items that provide an overall CIQOL score. The present study compares psychometric properties of the newly developed CIQOL instruments to two legacy PROMs commonly used in adult CI users.

Design:
Using a prospective cohort design, a sample of 334 adult CI users recruited from across the United States provided responses to (1) the CIQOL instruments; (2) a CI-specific PROM (Nijmegen Cochlear Implant Questionnaire, NCIQ); and (3) a general-health PROM (Health Utilities Index 3 [HUI-3]). Responses were obtained again after 1 mo. The reliability and validity of the CIQOL-35 Profile and CIQOL-10 Global instruments were compared with the legacy PROMs (NCIQ and HUI-3). Psychometric properties and construct validity of each instrument were analyzed using confirmatory factor analysis, item response theory (IRT), and test-retest reliability (using Pearson’s correlations), where appropriate.

Results:
All six CIQOL-35 Profile domains and the CIQOL-10 Global instrument demonstrated adequate to strong construct validity. The majority of the NCIQ subdomains and NCIQ total score had substantial confirmatory factor analysis model misfit, representing poor construct validity. Therefore, IRT analysis could only be applied to the basic sound performance and activity limitation subdomains of the NCIQ. IRT results showed strong psychometric properties for all CIQOL-35 Profile domains, the CIQOL-10 Global instrument, and the basic sound performance and activity limitation subdomains of the NCIQ. Test-retest reliability was strong for the CIQOL-35 Profile, CIQOL-10 Global, and NCIQ, but moderate to weak for the HUI-3; the hearing score of the HUI-3 demonstrated the weakest reliability.

Conclusion:
The CIQOL-35 Profile and CIQOL-10 Global are more psychometrically sound and comprehensive than the NCIQ and the HUI-3 for assessing QOL in adult CI users. Due to poor reliability, we do not recommend using the HUI-3 to measure QOL in this population. With validation and psychometric analyses complete, the CIQOL-35 Profile measure and CIQOL-10 Global instrument are now ready for use in clinical and research settings to measure QOL and real-world functional abilities of adult CI users.