Impact of prescribing vancomycin capsules vs liquid at discharge on readmissions for C. difficile infection.

Purpose: Clostridioides difficile infection (CDI) is a hospital-acquired infection commonly treated with oral vancomycin. An institutional policy aimed at reducing costs by substituting compounded liquid vancomycin for capsules may have the unintended consequence of having the liquid formulation prescribed at discharge, potentially delaying patients' access due to a lack of availability in pharmacies or lack of insurance coverage. This study aimed to evaluate hospital readmission rates of patients prescribed either vancomycin capsules or liquid upon discharge.

Methods: This was a retrospective cohort study conducted at an academic hospital using electronic health records data over a 6-year timeframe. The primary outcomes were all-cause and CDI-specific readmission rates within 30 days of discharge, and secondary outcomes included readmission rates within 60 and 90 days. Baseline characteristics were compared using chi-square or Mann-Whitney U tests. The hazard ratio (HR) for readmission was calculated using a Cox proportional hazards model, and readmission rates were analyzed using a Poisson regression model. All readmissions were confirmed by chart review.

Results: A total of 440 patients (61.3% female; median age, 58 years) were included; of these, 68% (n = 298) were prescribed vancomycin liquid and 32% (n = 142) a capsule form. Baseline characteristics were similar in the 2 groups, with the exception of the presence of inflammatory bowel disease (19.0% vs 6.4%, P < 0.0001) and median length of stay (6 days vs 8 days, P = 0.010). Patients prescribed vancomycin liquid were not more likely to be readmitted within 30 days relative to those prescribed capsule, with an adjusted HR for all-cause readmission of 1.58 (95% CI, 0.92-2.73) and an adjusted HR for CDI-specific readmission of 2.21 (95% CI, 0.72-6.76). However, patients prescribed liquid were more likely to be readmitted within 60 days, with an adjusted HR for all-cause readmission of 1.87 (95% CI, 1.19-2.94) and an adjusted HR for CDI-specific readmission of 2.84 (95% CI, 1.14-7.06).

Conclusion: A hospital pharmacy practice implemented to reduce medication costs may impact vancomycin prescribing at discharge and, in turn, may negatively impact readmission rates for patients with CDI treated with oral vancomycin.