Reliability of patient-reported outcome instruments in US adults with hemophilia: The Pain, Functional Impairment and Quality of life (P-FiQ) study

Background: Hemophilia is marked by frequent joint bleeding, resulting in pain and functional impairment. Objective: This study aimed to assess the reliability of five patient-reported outcome (PRO) instruments in people with hemophilia (PWH) in a non-bleeding state. Methods: Adult male PWH of any severity and inhibitor status, with a history of joint pain or bleeding, completed a pain history and five PRO instruments (EQ-5D-5L, Brief Pain Inventory v2 [BPI], International Physical Activity Questionnaire [IPAQ], Short Form 36 Health Survey v2 [SF-36v2], and Hemophilia Activities List [HAL]) during their routine comprehensive care visit. Patients were approached to complete the PRO instruments again at the end of their visit while in a similar non-bleeding state. Concordance of individual questionnaire items and correlation between domain scores were assessed using intra-class correlation coefficient (ICC). Results: Participants completing the retest (n=164) had a median age of 33.9 years. Median time for completion of the initial survey with PRO instruments was 36.0 minutes and for the five PRO instruments, median retest time was 21.0 minutes. The majority of participants had hemophilia A (74.4%), were white and non-Hispanic (72.6%), and self-reported arthritis/bone/joint problems (61%). Median/mean test-retest concordance was EQ-5D-5L 80.0%/79.1%, BPI 54.5%/58.9%, IPAQ 100%/100%, SF-36v2 77.8%/76.4%, and HAL 77.4%/75.9%. ICCs for test-retest reliability were EQ-5D-5L index 0.890; BPI - severity 0.950; BPI - interference 0.920; IPAQ total activity 0.940; SF-36v2 overall health 0.910; HAL total score 0.970. Conclusion: All five PRO scales showed acceptable test-retest reliability in adult PWH. Therefore, the choice of instrument to be used for research or clinical care should be driven by instrument characteristics other than reliability.