| Clostridium difficile infection (CDI) is a serious cause of infectious diarrhea in the United States. The new epidemic of CDI has been associated with the emergence of the NAP1/BI/027 strain, which has been linked to severe disease outcomes. It is unknown whether having the NAP1/BI/027strain as the cause of CDI is associated with increased morbidity and mortality, independent of the effect of host risk factors. This was a post hoc analysis of two phase 3 clinical trials comparing fidaxomicin vs. vancomycin for treatment of CDI. A propensity score for patients with CDI caused by the NAP1/BI/027 strain versus patients who did not have the strain was calculated. The outcomes assessed were disease severity, clinical cure and disease recurrence. Three different applications of the propensity score were used to assess disease outcomes: logistic regression (using quintiles of propensity score), matching and inverse probability weighting. Of the 792 patients with typed strains, 283 (35%) patients had the NAP1/BI/027 strain. Based on univariate analysis, patients with the NAP1/BI/027 strain were older, more likely to have a chronic disease and be exposed to antibiotics within two weeks of study enrollment. After controlling for the quintile of propensity, having the NAP1/BI/027 strain as the cause of CDI was associated with decreased cure (OR 0.42, 95% CI 0.27-0.64) as compared with not having the strain. However, having the NAP1/BI/027 strain as the cause for disease was not associated with disease severity (OR 1.08; 0.72-1.63). There was a trend towards higher disease recurrence rates among the patients with the NAP1/BI/027 strain (OR 1.33; 95% CI 0.86-2.04). After propensity score adjustment, patients with the NAP1/BI/027 strain do not have more severe disease than patients without the strain but appear to have reduced cure rates, regardless of underlying risk factors for disease. Patients with the NAP1/BI/027 strain as the cause of CDI may be at higher risk of recurrence compared to patients without the strain. |
