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035 VALIDATION OF THE CROHN DISEASE ACTIVITY INDEX AS A MEASURE OF POST-OPERATIVE DISEASE RECURRENCE TD Walters, AH Steinhart, C Bernstein, W Tremaine, BG Wolff, S Ross, R Parkes, M McKenzie, RS McLeod BACKGROUND/AIMS: Objective measures of disease activity are important as endpoints in randomized controlled trials (RCT). The Crohn Disease Activity Index (CDAI) has been used in medical trials with scores <150 indicative of remission. Its value in assessing post-operative recurrence is unknown. Taking advantage of an international, prospective, RCT investigating post-operative disease recurrence, we examined the association between a combined clinical/endoscopic assessment of disease activity and the CDAI. We desired to determine the suitability of the CDAI as a single post-operative outcome measure.
University of Toronto, Toronto, Ontario; University of Manitoba, Winnipeg, Manitoba; Mayo Clinic, Rochester, Minnesota, USA; University of Calgary, Calgary, Alberta; Samuel Lunenfeld Research Institute; Mt Sinai Hospital, Toronto, Ontario
METHOD: 120 patients (38% male) from 16 surgical units were included in an RCT comparing surgical techniques. All underwent clinical and colonoscopic evaluation 12 months post ileocolic resection, at a mean age of 39.7 yrs (±13.5). Outcomes were adjudicated by a three person committee and consensus reached. Endoscopic appearance was assessed using the Rutgeerts score (i0-i4). Symptomatic disease recurrence was defined by the composite of symptom severity warranting therapy and an endoscopic score =>i2. 88 (73%) subjects had CDAIs calculated according to established criteria. Comparisons were made using both non-parametric methods and the Receiver Operator Curve (ROC).
RESULTS: 35 (40%) patients had evidence of recurrent disease (23% symptomatic, 17% endoscopic only) by 12 months. 7% had endoscopy scores >i2 in the absence of symptoms. Median CDAI for symptomatic recurrence was 215 (IQR: 116 to 280); significantly different from asymptomatic subjects (Median 70, IQR 40 to 125, p<0.001). The area under the ROC for symptomatic disease and CDAI was 0.80 (95% CI 0.67 to 0.93, p<0.001). Recurrence was best predicted by a CDAI of =>148 (sensitivity 70%, specificity 85%, PPV 58% and NPV 91%). CDAI did not differentiate between endoscopic scores => or < i2 in the absence of significant symptoms (median 64 vs 88, p=0.99).
CONCLUSIONS: This study confirms that a CDAI of 150 is the best cutpoint for assessing disease activity. CDAI is useful in assessing outcome in postoperative RCTs. However, given a PPV <60%, it does not replace combined clinical/endoscopic evaluation as a single outcome measure in the assessment of post-operative disease recurrence.