A survey-based index was validated for measuring disease activity in inflammatory bowel disease. An evaluation study

ObjectiveCrohn's disease is a highly distressful chronic disorder, characterized by frequent relapses. A symptom-based disease activity index was developed for use in epidemiological research.Study Design and SettingOne hundred and six consecutive patients presenting to a tertiary referral hospital in Southern Germany in 2004–2005 participated in a questionnaire-based survey. As a reference standard, disease activity was assessed using a clinical index (Crohn's Disease Activity Index [CDAI], based on symptoms reported to physician, laboratory markers, and physician assessed signs). A linear regression equation was calculated based on the survey data on severity of symptoms (dependent variable: CDAI). Survey index scores (S-CDAI) were then calculated using the estimated coefficients for pain, stools, and general well-being in an independent data set.ResultsS-CDAI and CDAI showed moderate agreement (kappa = 0.57 for relapse vs. remission). High activity (high S-CDAI) correlated negatively with high quality of life (disease specific: Short Inflammatory Bowel Disease Quality-of-Life Questionnaire; r = −0.67; generic: Short Form 36 physical summary score, r = −0.47). Test–retest reliability and sensitivity for change were good (intraclass correlation coefficient 0.81).ConclusionA useful, valid, and reliable disease activity score was developed, which will facilitate meaningful survey research in this chronic disorder.