Optimal vancomycin dose in the treatment of Clostridium difficile infection, antimicrobial stewardship initiative

C. difficile infections (CDI) are increasingly recognized as a leading cause of infectious diarrhea, with increasing morbidity and mortality. Treatment primarily centers around oral vancomycin treatment. A wide range of dosing regimens exist in clinical practice, with little evidence to help distinguish the therapeutic benefit between them. This is a retrospective cohort study conducted at an academic medical center that enrolled adult patients admitted with CDI. The primary outcome was a composite of complete or partial cure at the end of treatment and was assessed using a test of equivalency with a 20% equivalency limit. Subjects were divided into low dose (125 mg) or high dose (250 mg or 500 mg) of oral vancomycin dosed every 6 hours. Overall, 78 patients were included who received low dose vancomycin and 33 who received high dose. Generally, the two groups were similar, except the low dose group had significantly more leukocytosis and less ICU admission or hypotension compared to the high dose group. Equivalency between the two treatment groups was demonstrated (Absolute Risk Difference -0.022, 90% confidence interval: -0.13 to 0.18, p = 0.03). A stepwise logistic regression identified gender, baseline albumin, and ICU admission as significant predictors of the chance for complete or partial cure. No differences between groups for the secondary outcomes of 90-day readmission/recurrence, 30-day all-cause mortality, or time to resolution of diarrhea were demonstrated. Low dose oral vancomycin was demonstrated to result in equivalent outcomes compared to high dose vancomycin for the treatment of CDI.