Co-morbidities as predictors of mortality in Clostridium difficile infection and derivation of the ARC predictive score.

Clostridium difficile associated diarrhoea (CDAD) has increased significantly in the last 15 years, but predictors of outcome are inadequately understood. This was a cohort study of 2761 patients in North East England between 2002 and 2009, with the end-point of mortality at 30 days. The role of age, gender and co-morbidities was examined by binary logistic regression. Rounded odds ratios were used to develop a predictive score. A predictive score based on age, renal disease and cancer (ARC score) differentiated groups with differing risk of 30-day mortality (risk for score of 0-3 was 9-21%, score of 4-7 was 31-48% and score of 8 was 66%). Co-morbidities were shown to be important predictors of outcome in CDAD, and can be combined with age in the ARC score to assess the likelihood of survival. This requires further validation in other populations, but has important implications for clinical and research practice.