Validation of the Standardized Outcomes in Nephrology - Life Participation (SONG-LP) Instrument in People Receiving Dialysis

Introduction: Life participation (LP) has been identified as a critically important core outcome for trials in people receiving dialysis. We aimed to validate the Standardized Outcomes in Nephrology-LP (SONG-LP) instrument in people receiving dialysis. Methods: A psychometric evaluation of the SONG-LP instrument in adults receiving dialysis (including hemodialysis [HD] and peritoneal dialysis [PD]) was completed through a multinational online survey. Internal consistency, test-retest reliability, convergent validity, discriminant validity, and known group comparisons (for dialysis modality and dialysis duration) were assessed. Results: In total, 250 adults receiving dialysis (69 PD, 47 home HD, and 134 in-center HD) from 13 countries completed surveys at baseline, and 204 participants (82%) completed the survey 1 week later. The SONG-LP instrument demonstrated strong internal consistency (Cronbach's α = 0.89, 95% confidence interval [CI]: 0.87-0.91, baseline) and test-retest reliability over 1 week (intraclass correlation coefficient [ICC] of 0.76, 95% CI: 0.70-0.81). There was a high correlation (0.76, 95% CI: 0.69-0.81) with the Patient-Reported Outcomes Measurement Information System (PROMIS) Ability to Participate in Social Roles and Activities (APS) Short Form 8a. There was moderate to high correlation with measures assessing concepts related to LP measured by the EuroQol-5 Dimension (EQ-5D) (0.62, 95% CI: 0.53 - 0.69) and PROMIS Cognitive Functional Abilities Subset Short Form 4a (0.49, 95% CI: 0.38 - 0.57). Conclusion: The SONG-LP instrument is an internally consistent and reliable measure of LP for people receiving dialysis. This study provides preliminary evidence supporting its psychometric validity, offering a foundation for further evaluation of its use in clinical trials.