['The incidence, recurrence, and all-cause mortality rate for Clostridium difficile-associated diarrhea (CDAD) has increased markedly over the past 10 years despite treatment. Low vitamin D levels are known to impair immune responses to infection and are associated with increased mortality. We compared the role of patient comorbidity measured by the Charlson Comorbidity Index (CCI) with vitamin D levels to ascertain whether vitamin D levels were an independent variable affecting the outcome of CDAD or a marker of overall comorbidity.', "A prospective cohort study studied 62 patients hospitalized between 2008 and 2009 with manifestations of CDAD and a positive C. difficile toxin assay. All patients received standard antibiotics (metronidazole and/or vancomycin). Their status at 30-day follow up was classified as resolved or recurred/expired. Patients' CCI was calculated using their medical history. Logistic regression analysis of variables including 25-hydroxyvitamin D, CCI, age, gender, white blood cell count (WBC), albumin and residence type were performed.", 'There were 62 patients (43.6% men, 56.4% women) with CDAD; mean age was 75 ± 17 years. At 30-day follow up, 28 (45.2%) expired, 10 (16.1%) had persistent or recurrent diarrhea and 24 (38.7%) resolved. Nonresolution was seen in 38 (61.3%). There was no significant association between 30-day resolution status and CCI, gender, WBC, albumin level or residence type. Two variables were found to be independent predictors of resolution of CDAD: normal vitamin D levels (p = 0.028) and age <70 years (p = 0.024). Subjects with low vitamin D were 4.75 times more likely to fail to resolve CDAD than subjects with normal Vitamin D.'] Is low vitamin D level an independent predictor of poor outcomes in Clostridium difficile-associated diarrhea?