Ulcerative Colitis Patients With Clostridium difficile are at Increased Risk of Death, Colectomy, and Postoperative Complications: A Population-Based Inception Cohort Study

OBJECTIVES: Clostridium difficile (C. difficile) may worsen the prognosis of ulcerative colitis (UC). The objectives of this study were to: (i) validate the International Classification of Diseases-10 (ICD-10) code for C. difficile; (ii) determine the risk of C. difficile infection after diagnosis of UC; (iii) evaluate the effect of C. difficile infection on the risk of colectomy; and (iv) assess the association between C. difficile and postoperative complications. METHODS: The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated by comparing ICD-10 codes for C. difficile with stool toxin tests. A population-based surveillance cohort of newly diagnosed UC patients living in Alberta, Canada were identified from 2003 to 2009 (n=1,754). The effect of a C. difficile infection on colectomy was modeled using competing risk survival regression after adjusting for covariates. The effect of a C. difficile infection on postoperative complications was assessed using a mixed effects logistic regression model. RESULTS: The sensitivity, specificity, PPV, and NPV of the ICD-10 code for C. difficile were 82.1%, 99.4%, 88.4%, and 99.1%, respectively. The risk of C. difficile infection within 5 years of diagnosis with UC was 3.4% (95% confidence interval (CI): 2.5-4.6%). The risk of colectomy was higher among UC patients diagnosed with C. difficile (sub-hazard ratio (sHR)=2.36; 95% CI: 1.47-3.80). C. difficile increased the risk of postoperative complications (odds ratio=4.84; 95% CI: 1.28-18.35). C. difficile was associated with mortality (sHR=2.56 times; 95% CI: 1.28-5.10). CONCLUSIONS: C. difficile diagnosis worsens the prognosis of newly diagnosed patients with UC by increasing the risk of colectomy, postoperative complications, and death.