Measuring irritable bowel syndrome patient-reported outcomes with an abdominal pain numeric rating scale

Aliment Pharmacol Ther. 2009 Dec 1;30(11-12):1159-70. doi: 10.1111/j.1365-2036.2009.04144.x. Epub 2009 Sep 12.


Background: Controversy exists on how to measure patient-reported outcomes in irritable bowel syndrome (IBS) clinical trials effectively. Pain numeric rating scales (NRS) are widely used in the non-IBS pain literature. The Food and Drug Administration has proposed using the NRS in IBS.

Aim: To test the psychometrics of an abdominal pain NRS in IBS. Methods We analysed data from a longitudinal cohort of Rome III IBS subjects. At entry, subjects completed a 10-point NRS, bowel symptoms, IBS severity measurements (IBS-SSS, FBDSI), health-related quality of life indices (IBS-QOL, EQ5D), and the Worker Productivity Activity Index (WPAI). We repeated assessments at 3 months along with a response scale to calculate the minimal clinically important difference.

Results: There were 277 subjects (82% women; age = 42 +/- 15) at baseline and 90 at 3 months. The NRS correlated cross-sectionally with IBS-SSS (r = 0.60; P < 0.0011), FBDSI (r = 0.49; P < 0.0001), IBS-QOL (r = 0.43; P < 0.0001), EQ5D (r = 0.48; P < 0.0001), presenteeism (r = 0.39; P < 0.0001), absenteeism (r = 0.17; P = 0.04) and distension (r = 0.46; P < 0.0001), but not stool frequency or form. The minimal clinically important difference was 2.2 points, correlating with a 29.5% reduction over time.

Conclusions: An abdominal pain NRS exhibits excellent validity and can be readily interpreted with a minimal clinically important difference in patients with IBS. These data support the use of the NRS in IBS clinical trials.

Publication types

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

MeSH terms

  • Abdominal Pain / psychology*
  • Female
  • Humans
  • Irritable Bowel Syndrome / complications
  • Irritable Bowel Syndrome / psychology*
  • Male
  • Middle Aged
  • Psychometrics
  • Reproducibility of Results
  • Severity of Illness Index
  • Treatment Outcome