Impact of Updated Clinical Practice Guidelines on Outpatient Treatment for Clostridioides difficile Infection and Associated Clinical Outcomes

Background: The 2017 Infectious Diseases Society of America/Society for Healthcare Epidemiology of America (IDSA/SHEA) Clostridium (Clostridioides) difficile infection (CDI) guideline update recommended treatment with fidaxomicin or vancomycin for CDI. We aimed to examine outpatient CDI treatment utilization before and after the guideline update and compare clinical outcomes associated with fidaxomicin versus vancomycin use. Methods: A pre-post study design was employed using Medicare data. CDI treatment utilization and clinical outcomes (4- and 8-week sustained response, CDI recurrence) were compared between patients indexed from April-September 2017 (preguideline period) and those indexed from April-September 2018 (postguideline period). Clinical outcomes associated with fidaxomicin versus vancomycin were compared using propensity score-matched analyses. Results: From the pre- to postguideline period, metronidazole use decreased (initial CDI: 81.2% to 53.5%; recurrent CDI: 49.7% to 27.6%) while vancomycin (initial CDI: 17.9% to 44.9%; recurrent CDI: 48.1% to 66.4%) and fidaxomicin (initial CDI: 0.87% to 1.63%; recurrent CDI: 2.2% to 6.0%) use increased significantly (P <. 001 for all). However, clinical outcomes did not improve. In propensity score-matched analyses, fidaxomicin versus vancomycin users had 4-week sustained response rates that were higher by 13.5% (95% confidence interval [CI], 4.0%-22.9%; P =. 0058) and 30.0% (95% CI, 16.8%-44.3%; P =. 0002) in initial and recurrent CDI cohorts, respectively. Recurrence rates were numerically lower for fidaxomicin in both cohorts. Conclusions: Vancomycin use increased and metronidazole use decreased after the 2017 guideline update. Fidaxomicin use increased but remained low. Improved outcomes associated with fidaxomicin relative to vancomycin suggest benefits from its greater use in Medicare patients.