Psychometric Assessment of PROMIS-29 As a Measure of Health Status After Metabolic and Bariatric Surgery: A Prospective Cohort Study

Background PROMIS-29 may be a valuable questionnaire to assess patient-reported outcomes after metabolic and bariatric surgery (MBS), but its psychometric properties in this context remain unclear. Objectives To assess the internal consistency, construct validity, and responsiveness of PROMIS-29 as a measure of recovery and longer-term outcomes after MBS. Setting Two university hospitals and a private surgical clinic in Canada. Methods Patients undergoing laparoscopic MBS completed the PROMIS-29 preoperatively, during the recovery period (postoperative weeks [POW] 1, 2, 3, and 4), and longer-term follow-up (postoperative months [POM] 6 and 12). Physical Health Summary (PHS) score and Mental Health Summary (MHS) score were derived from T-scores. Internal consistency was appraised using Cronbach's alpha. Construct validity and responsiveness were assessed via a priori hypotheses targeting known-group differences and expected postoperative health trajectories. Each measurement property was deemed acceptable if ≥75% hypotheses were confirmed. Results 351 patients were included (age 44±11, Body Mass Index (BMI) 45±8, 77% female, 71% sleeve gastrectomy). Internal consistency of PHS and MHS was acceptable (alpha>0.7). Construct validity during recovery was limited (PHS 3/8 [38%] and MHS 4/8 [50%] hypotheses confirmed). In the longer term, construct validity was not supported (PHS 0/6 and MHS 0/4). Responsiveness of PHS and MHS was limited in the recovery period (1/4 [25%]) but supported in the longer-term (2/2 [100%]). Conclusions PROMIS-29 scores were responsive to long-term health improvements after MBS but failed to differentiate groups who were expected to have distinct outcomes. Context-specific tools may be better suited to capture health trajectories post-MBS.