Background: The goal of our study is to determine the impact of chronologic age on risk of Clostridium difficile infection (CDI) in a population-based cohort of U.S. elderly persons.
Methods: We used Medicare claims data from 2010-2011 to identify new-onset CDI in persons aged 66 years and older in 2011. New-onset CDI cases in 2011 were identified by the ICD-9-CM diagnosis code 008.45 in any of the inpatient, outpatient, and physician claims files. The comparison group consisted of individuals in the Medicare 5% random sample without a diagnosis of CDI in 2011 or the last quarter of 2010. Logistic regression was used to identify risk factors for CDI, including age, gender, race, infections in the prior 3 months, and a comprehensive group of acute and chronic conditions and health care utilization in the past 12 months.
Results: 180,348 persons aged >= 66 years were newly coded for CDI in 2011, and were compared to 1,277,529 persons without evidence for CDI. Caucasians were at increased risk of CDI compared to other races (OR 1.3). The infections associated with greatest risk of CDI were septicemia (OR 13.4), pneumonia (OR 8.3), UTI (6.4), skin and soft tissue (OR 6.2), serious abdominal (OR 5.4) and oral infection (OR 5.4) in the 3 months before CDI. Comorbid chronic illnesses were associated with variable risk of CDI, with the highest ORs for anemia (OR 2.8), depression (OR 2.5), and metastatic cancer (OR 2.4). Hospitalizations originating in the emergency department (OR 1.4) and inpatient surgery (OR 1.6) were also associated with increased risk of CDI. After adjusting for infections and acute and chronic conditions and health care utilization in the past 12 months, age had no impact on CDI risk until age 86 and older (Figure).
Conclusion: In this population-based analysis, infections in the prior 3 months were associated with the largest risk of CDI. Age had little impact on the risk of CDI after controlling for underlying chronic illnesses, recent acute illnesses, and health care utilization in the prior year until individuals were very old (>= 86 years). Our results suggest that “biologic aging”, due largely to acute illnesses but also chronic conditions and contact with health care facilities had a bigger impact on risk of CDI than chronologic age per se.
C. Demont, Sanofi Pasteur: Employee , Salary
C. Mahe, Sanofi Pasteur: Employee , Salary
E. R. Dubberke, rebiotix: Consultant and Investigator , Consulting fee and Research support
sanofi-pasteur: Grant Investigator , Research grant
pfizer: Consultant , Consulting fee
Merck: Consultant and Investigator , Consulting fee and Research support
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