Potential underreporting of treated patients using a Clostridioides difficile testing algorithm that screens with a...

Area of Science:

• Infectious Diseases
• Clinical Microbiology
• Epidemiology

Background:

• The 2-step algorithm for Clostridioides difficile infection (CDI) diagnosis involves nucleic acid amplification testing (NAAT) followed by toxin assay.
• Patients who are NAAT positive but toxin negative (NAAT+/toxin-) are not reported as laboratory-identified CDI events to the National Healthcare Safety Network.
• This reporting gap may lead to underestimation of CDI prevalence and impact patient management.

Purpose of the Study:

• To compare outcomes between patients with NAAT+/toxin- and NAAT+/toxin+ results.
• To identify factors associated with treatment decisions for NAAT+/toxin- patients.

Main Methods:

• Retrospective observational study across 36 laboratories at 5 Emerging Infections Program sites.
• Defined CDI cases using the 2-step algorithm (2018-2020) in patients aged ≥1 year.
• Used multivariable and mixed-effects logistic regression to compare outcomes and identify treatment predictors.

Main Results:

• Of 1,801 cases, 1,252 were NAAT+/toxin- and 549 were NAAT+/toxin+.
• CDI treatment was less frequent in NAAT+/toxin- cases (71.5%) compared to NAAT+/toxin+ cases (95.9%).
• NAAT+/toxin- status was associated with lower recurrence but not CDI-related complications. Predictors for NAAT+/toxin- treatment included high white blood cell count, frequent unformed stools, and laboratory interpretive comments.

Conclusions:

• The 2-step algorithm may lead to underreporting of clinically relevant CDI cases (NAAT+/toxin-).
• Disease severity indicators and laboratory reporting nuances influence treatment decisions for NAAT+/toxin- patients.
• Further evaluation of the 2-step algorithm's clinical and public health implications is warranted.