975. Clostridium difficile Infection and Antibiotic Prescription Rates in the Community: Explaining the Gender Gap

BACKGROUND: Previous studies have reported higher incidence rates of community-associated Clostridium difficile infection (CA-CDI) in women than in men. This cross-sectional population-based study examines whether this difference in CA-CDI rates across genders is driven by or independent of antibiotic use. METHODS: Medicaid and State Employee Health Plan pharmacy claims for outpatient oral antibiotics and associated medical claims were utilized for estimation of community antibiotic prescription rates in South Carolina population 18 to 64 years of age from January 1, 2015 to December 31, 2015. CA-CDI cases were identified from National Healthcare Safety Network (NHSN) and South Carolina Infectious Disease and Outbreak Network (SCION) through complete enumeration of South Carolina population of the same age and study period as above. Incidence rates of CA-CDI were reported in both men and women 18–39 and 40–64 years of age before and after adjustments for antibiotic prescription rates in the same gender and age group. The 95% confidence intervals (CI) were calculated to examine statistical difference in incidence rates across genders within the same age group. RESULTS: During the calendar year 2015, a total of 1,564 CA-CDI cases were identified in South Carolina residents 18–64 years of age. The incidence rate of CA-CDI per 100,000 person-years was higher in women than in men in age groups 18–39 years (37.3 [95% CI: 32.8–41.8] vs. 21.0 [95% CI: 17.6–24.4]) and 40–64 years (86.4 [95% CI: 80.1–92.8] vs. 56.6 [95% CI: 51.2–61.9]. Similarly, antibiotic prescription rates per 100 person-years were higher in women than men in the 2 respective age groups (118.8 [95% CI: 118.3–119.3] vs. 54.3 [95% CI: 53.9–54.8] and 130.4 [95% CI: 129.8–130.9] vs. 83.8 [95% CI: 83.3–84.4]. After adjustments for antibiotic prescriptions, there was no significant difference in the incidence rates of CA-CDI per 100,000 prescriptions between women and men 18–39 years of age (31.4 [95% CI: 27.6–35.2] vs. 38.6 [95% CI: 32.4–44.8] and 40–64 years old (66.3 [95% CI 61.5–71.2] vs. 67.5 [95% CI: 61.1–73.8]). CONCLUSION: Higher crude incidence rates of CA-CDI in women are likely due to higher outpatient antibiotic prescription rates in women when compared with men. DISCLOSURES: P. B. Bookstaver, CutisPharma: Scientific Advisor, <$1,000. Melinta Therapeutics: Speaker’s Bureau, <$1,000.