Laboratory Positive Clostridium difficile: BioSense 2007

Background: Reports indicate that Clostridium difficile-associated disease (CDAD) incidence and severity has increased. This epidemiological change in the disease pattern is partially explained by the emergence of a hypervirulent strain causing disease in both healthcare and community settings. The purpose of this study is to describe the epidemiology and rate of CDAD in BioSense, an electronic surveillance system receiving data from >400 non-federal hospitals. Methods: We identified positive C. difficile toxin assays in laboratory data sent to BioSense in 2007 using SNOMED codes and text parsing methods. Currently, only 37 BioSense hospitals send laboratory result data. Laboratory data were merged with administrative records to determine healthcare setting (eg., inpatient, outpatient), patient demographics, and visit denominator data for rate calculations. Results: A total of 2,144 patients from 28 hospitals in 21 states had positive CDAD assays. Of those patients, 1,929 (90%) were either admitted to the hospital or already in the hospital at the time of the test. The overall prevalence rate in the inpatient setting was 5.1 per 1,000 hospital admissions. Of those with CDAD positive tests, 1,204 (56%) were females; the mean and median age was 65 and 69 years, respectively. For those ?65 years of age, the prevalence rate of inpatient CDAD was 10.9 per 1,000 hospital admissions. Discussion: CDAD is a disease of public health concern. Although BioSense is not representative of the entire U.S. population, the rate of positive CDAD tests calculated from these data is consistent with reported studies. BioSense provides near real time automated data and is a useful resource in emergency response events and ongoing surveillance efforts.