Clostridium difficile-associated diarrhea in a region of Quebec from 1991 to 2003: a changing pattern of disease severity

Recent reports suggest that Clostridium difficile colitis may be evolving into a more severe disease. During the second half of 2002 we noted an increase in the number of patients with severe C. difficile-associated diarrhea (CDAD) in our institution. We describe cases of CDAD at our institution over a 13-year period and investigate changes in illness severity. We undertook a retrospective chart review of all cases of CDAD diagnosed at the Centre hospitalier universitaire de Sherbrooke from Jan. 1, 1991, to Dec. 31, 2003. Because the hospital serves a well-defined population of Quebec, we were also able to calculate population-based incidence during this period. We abstracted data on individual patients from patient charts and from hospital and pharmacy computer databases. We defined cases of CDAD as having a positive C. difficile cytotoxicity assay result, or endoscopic or histopathological evidence of pseudomembranous colitis. A case was considered complicated if one or more of the following was observed: megacolon, perforation, colectomy, shock requiring vasopressor therapy, or death within 30 days after diagnosis. A total of 1721 cases of CDAD were diagnosed during the study period. The incidence increased from 35.6 per 100,000 population in 1991 to 156.3 per 100,000 in 2003; among patients aged 65 years or more, it increased from 102.0 to 866.5 per 100,000. The proportion of cases that were complicated increased from 7.1% (12/169) in 1991-1992 to 18.2% (71/390) in 2003 (p < 0.001), and the proportion of patients who died within 30 days after diagnosis increased from 4.7% (8/169) in 1991-1992 to 13.8% (54/390) in 2003 (p < 0.001). A high leukocyte count (20.0 small ha, Cyrillic 10(9)/L or greater) and an elevated creatinine level (200 micromol/L or greater) were strongly associated with adverse outcomes: in 2003, 45 (40.9%) of 110 patients with a high leukocyte count or creatinine level, or both, had complicated CDAD and 28 (25.5%) died within 30 days after diagnosis. After adjustment for age and other confounding factors, patients initially given oral vancomycin therapy had a risk of progression to complicated CDAD that was 79% lower than the risk among patients initially treated with metronidazole (adjusted odds ratio 0.2, 95% confidence interval 0.06-0.8, p = 0.02). An epidemic of CDAD with an increased case-fatality rate has had important consequences on the elderly population of our region. Our observational data suggest that the equivalence of va