2376. Incidence of Clostridioides difficile Infection Among United States Medicare Advantage Enrollees

BACKGROUND: Clostridioides difficile infection (CDI) may be life-threatening, and individuals aged ≥ 65 years are at increased risk. CDI burden among Medicare fee-for-service enrollees and nursing home residents in the United States have been characterized previously. The present study aimed to describe the incidence of CDI among Medicare Advantage Enrollees (MAEs), who account for 34% of all Medicare beneficiaries with enrollment increasing annually since 2004. METHODS: De-identified claims data for this retrospective cohort study were collected from the Optum® Clinformatics® Data Mart and included MAEs aged ≥ 65 years with continuous enrollment for ≥ 1 year before January 1, 2016, followed through death or disenrollment. CDI incidence was defined using the International Classification of Diseases 9th Revision diagnosis code of 008.45 or 10th Revision code of A04.7 (other than admitting diagnosis) or by treatment with nontopical metronidazole, oral vancomycin, or fidaxomicin within 14 days of CDI test. Incident CDI cases were identified from January 1 to December 31, 2016, and required that no CDI occurred within the previous 60 days in 2016. Incidence in 2016 was calculated as CDI cases and CDI patients per 100,000 person-years (PY) of observation time. RESULTS: Of 2,542,341 MAEs analyzed, 15,201 patients (0.6%) experienced a total of 18,842 incident CDI episodes. Overall, incidence rates were 762.8 CDI cases and 616.5 CDI patients per 100,000 PY. Incidence increased with age (539.6, 847.3, and 1259.6 cases per 100,000 PY in patients aged 65‒74 years, 75‒84 years, and ≥ 85 years, respectively). Most episodes (50.9%) were community acquired; the remaining 37.7% and 11.4% of episodes were hospital acquired and indeterminate, respectively. CDI patients were more likely than non-CDI patients to be older (mean age, 78.3 vs. 76.1 years, P < 0.0001), be women (64.5% vs. 58.1%, P < 0.0001), or have comorbidities (mean Charlson comorbidity index score, 4.5 vs. 1.8, P < 0.0001). CONCLUSION: CDI incidence rates in the Medicare Advantage population were similar to those reported previously in the Medicare fee-for-service population and nationally among adults aged ≥ 65 years. Data are consistent with a high CDI burden among older US adults. Funding: Pfizer. DISCLOSURES: All authors: No reported disclosures.