Cox regression analysis of the proportion of patients remaining in remission during azathioprine treatment related to minimum observed white blood cell (WBC) count during treatment (324 patients). Cox regression analysis of the proportion of patients remaining in remission during azathioprine treatment related to minimum observed white blood cell (WBC) count during treatment (324 patients). Patients with a WBC count of less than 5.0×109 were more likely to remain in remission (p=0.03). A G Fraser et al. Gut 2002;50:485-489 Copyright © BMJ Publishing Group Ltd & British Society of Gastroenterology. All rights reserved.