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Incidence of Polymerase Chain Reaction–Diagnosed Clostridium difficile in a Large High-Risk Cohort, 2011-2012



      To describe incidence rates (IRs) of polymerase chain reaction (PCR)–diagnosed Clostridium difficile infection (CDI) in a large high-risk cohort.

      Patients and Methods

      Members of Kaiser Permanente Southern California 1 year or older who were admitted to any of 14 Kaiser Permanente hospitals from January 1, 2011, through December 31, 2012, were included in the study. The CDI cases were identified by PCR in the inpatient and outpatient settings. The CDI IRs per 10,000 inpatient-days are estimated by year, surveillance category, age, sex, race/ethnicity, and Charlson comorbidity index. Recurrence rates are presented by age, sex, and race/ethnicity. Death and colectomy in the 30 days after CDI diagnosis, white blood cell count, and serum creatinine level are assessed.


      Among 268,655 patients, 4286 (1.6%) had CDI. Among these patients, 671 (15.7%) had recurrent infections. The IR was highest among community-onset, health care facility–associated infections (11.1 per 10,000 inpatient-days). The CDI IRs differed by age, sex, and race/ethnicity. Overall, 528 patients (12.3%) died within 30 days of a positive CDI test result. The CDI IRs increased 34% with implementation of PCR testing.


      Increasingly, PCR is being used because of its higher diagnostic sensitivity. Reassessing the epidemic using PCR updates our understanding of CDI risk. Our capacity to identify patients presenting in the outpatient setting after discharge provides a more accurate picture of health care–associated CDI rates, particularly because the community appears to assume an increasing role in CDI onset and possibly transmission. The CDI burden differs by race, comorbidity, sex, and previous health care use. The detected increase in CDI incidence after transitioning to PCR diagnosis was modest compared with previous studies.

      Abbreviations and Acronyms:

      CDI (Clostridium difficile infection), ED (emergency department), EIA (enzyme immunoassay), HCF (health care facility), HIV (human immunodeficiency virus), ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification), IR (incidence rate), KPSC (Kaiser Permanente Southern California), PCR (polymerase chain reaction), WBC (white blood cell)
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