Construct validity and responsiveness of the abdominal surgery impact scale in the context of recovery after colorectal surgery

BACKGROUND: The Abdominal Surgery Impact Scale is a patient-reported outcome measure that evaluates quality of life after abdominal surgery. Evidence supporting its measurement properties is limited. OBJECTIVE: This study aimed to contribute evidence for the construct validity and responsiveness of the Abdominal Surgery Impact Scale as a measure of recovery after colorectal surgery in the context of an enhanced recovery pathway. DESIGN: This is an observational validation study designed according to the Consensus-based Standards for the Selection of Health Measurement Instruments checklist. SETTING: This study was conducted at a university-affiliated tertiary hospital. PATIENTS: Included were 100 consecutive patients undergoing colorectal surgery (mean age, 65; 57% male). INTERVENTION: There were no interventions. MAIN OUTCOME MEASURES: Construct validity was assessed at 2 days and 2 and 4 weeks after surgery by testing the hypotheses that Abdominal Surgery Impact Scale scores were higher 1) in patients without vs with postoperative complications, 2) with higher preoperative physical status vs lower, 3) without vs with postoperative stoma, 4) in men vs women, 5) with shorter time to readiness for discharge (≤4 days) vs longer, and 6) with shorter length of stay (≤4 days) vs longer. To test responsiveness, we hypothesized that scores would be higher 1) preoperatively vs 2 days postoperatively, 2) at 2 weeks vs 2 days postoperatively, and 3) at 4 weeks vs 2 weeks postoperatively. RESULTS: The data supported 3 of the 6 hypotheses (hypotheses 1, 5, and 6) tested for construct validity at all time points. Two of the 3 hypotheses tested for responsiveness (hypotheses 1 and 2) were supported. LIMITATIONS: This study was limited by the risk of selection bias due to the use of secondary data from a randomized controlled trial. CONCLUSIONS: The Abdominal Surgery Impact Scale was responsive to the expected trajectory of recovery up to 2 weeks after surgery, but did not discriminate between all groups expected to have different recovery trajectories. There remains a need for the development of recovery-specific, patient-reported outcome measures with adequate measurement properties.