Measurement of Inflammatory Bowel Disease Symptoms: Reliability of an Abbreviated Approach to Data Collection

Abstract

Background: The Crohn's Disease Activity Index (CDAI) and Mayo score for ulcerative colitis (UC) require symptom recall and/or use of a symptom diary. We examined patients' abilities to recall their symptoms and the day-to-day variability of symptoms.

Methods: Patients with UC or CD completed a questionnaire including items from the short CDAI (sCDAI) and the 6-point Mayo score. Patients were randomized to receive a follow-up questionnaire testing recall of the bowel symptom items between 1 and 7 days later. In a second study, patients completed a 7-day electronic diary recording their symptoms. sCDAI and 6-point Mayo scores were computed. Analyses estimated daily variability in the indices and misclassification rates when using fewer than 7 days of data.

Results: 100%, 82%, and 90% of CD participants recalled the same disease activity status (i.e., active versus remission) as reported on the initial survey when the follow-up questionnaire was administered 1 to 2, 3 to 5, and 6 to 8 days later, respectively. Compared with using 7 days of data, when using only day 7 data, 3.7% of patients with CD were misclassified as active or inactive. Disease activity was misclassified in 2.8%, 4.9%, and 3.3% of patients by using the last 2, 3, or 4 days, respectively. Results were similar for patients with UC.

Conclusions: Patients with CD and UC demonstrated good recall of bowel symptoms for up to 8 days. Additionally, bowel symptoms have relatively little variability within a 7-day period allowing for accurate computation of the sCDAI and 6-point Mayo score using 1 to 3 days of data.

Figure 1. Changes in disease activity in study 1

(A) The number of participants with CD (n=72) and UC (n=28) who switched from active to inactive or vice versa; (B) Percent agreement of CD activity status stratified by number of days from baseline measurement to recall of symptoms; (C and D) Box and whiskers plot of the difference of sCDAI scores at baseline and follow-up, stratified by timing of follow-up survey (C) and baseline disease activity (D).

Figure 2. Agreement of sCDAI computed with 7 days of data and with fewer days of data collection

(A) Correlation of the 7-day sCDAI with only day 7 (r²=0.83 for the regression line shown); (B) Correlation of the 7-day sCDAI with days 5–7 (r²=0.93); (C and D) Agreement of categorization of disease activity using all 7 days of data with available day 7 data (C) and available days 5–7 data (D).