Psychometric evaluation of patient-reported outcomes in irritable bowel syndrome randomized controlled trials: a Rome Foundation report

Gastroenterology. 2009 Dec;137(6):1944-53.e1-3. doi: 10.1053/j.gastro.2009.08.047. Epub 2009 Aug 23.

Abstract

Background & aims: There is debate about how best to measure patient-reported outcomes (PROs) in irritable bowel syndrome (IBS). We pooled data to measure the psychometric properties of IBS end points, including binary responses (eg, "adequate relief") and 50% improvement in symptom severity.

Methods: We pooled data from 12 IBS drug trials involving 10,066 participants. We tested the properties of binary response and 50% improvement end points, including the impact of baseline severity on performance, and measured construct validity using clinical anchors.

Results: There were 9044 evaluable subjects (age, 44 years; 85% female; 58% IBS constipation-prominent [IBS-C]; 31% IBS diarrhea-prominent [IBS-D]). Using the binary end point, the proportion responding in the mild, moderate, and severe groups was 42%, 40%, and 38%, respectively (P = .0008). There was no effect of baseline severity on binary response (odds ratio [OR], 0.99; 95% confidence interval [CI], 0.99-1.0; P = .07). The proportions reaching 50% improvement in pain were 45%, 41%, and 41%, respectively; there was a small, yet significant, impact of baseline severity (OR, 1.04; 95% CI, 1.03-1.05; P < .0001) that did not meet clinical relevance criteria. Both end points revealed strong construct validity and detected "minimally clinically important differences" in symptoms. Both provided better discriminant spread in IBS-D than IBS-C.

Conclusions: Both the traditional binary and 50% improvement end points are equivalent in their psychometric properties. Neither is impacted by baseline severity, and both demonstrate excellent construct validity. They are optimized for the IBS-D population but also appear valid in IBS-C.

Publication types

  • Meta-Analysis
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Abdominal Pain / etiology
  • Abdominal Pain / prevention & control*
  • Abdominal Pain / psychology
  • Adult
  • Female
  • Humans
  • Irritable Bowel Syndrome / complications
  • Irritable Bowel Syndrome / diagnosis
  • Irritable Bowel Syndrome / psychology
  • Irritable Bowel Syndrome / therapy*
  • Logistic Models
  • Male
  • Odds Ratio
  • Pain Measurement*
  • Patient Satisfaction*
  • Predictive Value of Tests
  • Psychometrics*
  • Randomized Controlled Trials as Topic
  • Reproducibility of Results
  • Severity of Illness Index
  • Treatment Outcome