Objective: The Patient-Reported Outcomes Measurement Information System (PROMIS) aims to address the lack of generalizable and universal measure of patient-reported outcomes to assess health-related quality of life. It has not been validated for patients with chronic kidney disease. We aim to validate the PROMIS-57 and PROMIS-29 questionnaires among kidney transplant recipients.
Methods: A cross-sectional sample of stable kidney transplant recipients was recruited. Each participant completed PROMIS-57, a 57-question instrument covering seven domains-physical function, anxiety, depression, fatigue, pain, sleep disturbance, and social functioning-alongside validated legacy questionnaires [Patient Health Questionnaire (PHQ9), General Anxiety Disorder (GAD7), Edmonton Symptom Assessment Scale revised (ESASr), and Kidney Disease Quality of Life (KDQoL-36)]. PROMIS-29, a 29-question instrument, is nested within PROMIS-57 and measures the same domains. Structural validity of PROMIS was assessed with confirmatory factor analysis, reported using the Comparative Fit Index (CFI). Construct validity was assessed with known-groups comparisons. Internal consistency was evaluated with Cronbach's α and convergent validity was assessed with Spearman's Rho. Test-retest reliability was assessed through the intraclass correlation coefficient (ICC).
Results: Mean (± SD) age of the 177 participants was 50 (± 17), 57% were male and 55% Caucasian. Internal consistency of each domain was high (Cronbach's α > 0.88). Confirmatory factor analysis showed good structural validity for most domains (CFI > 0.95, RMSEA < 0.05). Test-retest reliability indicated good agreement (ICC > 0.6). Known-groups comparisons by clinical and socio-demographic differences were found as hypothesized.
Conclusions: Our results provide evidence that PROMIS-57 and PROMIS-29 are highly reliable and valid instruments among kidney transplant recipients. We propose it as a valuable tool to assess important domains of the illness experience.
Keywords: Kidney transplant; PROMIS; PROMIS-29; PROMIS-57; Patient-reported outcomes; Renal transplant; Validation study.