Daily Dose: Outpatient C. difficile Underdiagnosed in US

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Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

Last week, we reported on findings from a study published in Open Forum Infectious Diseases that described testing for Clostridioides difficile infection (CDI) among patients with medically attended diarrhea (MAD) in the outpatient setting, and the incidence of outpatient CDI.

The study

The study included adults aged ≥18 years treated for MAD at Kaiser Permanente Southern California and Kaiser Permanente Northwest between January 1, 2016, and December 31, 2021. Investigators identified MAD through International Classification of Diseases, Tenth Revision (ICD-10) and CDI via positive laboratory results. Incidence rates (IRs) of outpatient CDI were stratified by select demographic and clinical variables.

Outpatient CDI was defined for the purpose of the study as no hospitalization ≤7 days after specimen collection. Outpatient CDI burden 12 months following index date was measured by CDI-associated health care visits, as well as CDI testing and treatment.

The findings

Investigators identified 777 533 MAD episodes, of which 12.1% (93 964/777 533) were tested for CDI. Among those tested, 10.8% (10 110/93 964) were positive for CDI.

Outpatient CDI IR was 51 per 100 000 person-years (95% CI 49.8-52.2) but pointed to a decrease in incidence from 58.2 (95% CI 55.7–60.7) in 2016 to 45.7 (95% CI 43.7–47.8) in 2021.

When researchers evaluated associated health care utilization, they found that 44.1% of patients received an antibiotic 30 days before the index date of their first CDI episode.

Authors' comment

"There was a high incidence of outpatient CDI despite infrequent CDI testing among patients with MAD. The majority of those with outpatient CDI had no recent antibiotic use and no recent hospitalization. Further studies are needed to understand the source and management of medically attended outpatient CDI."

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