Failure of Risk-Adjustment by Test Method for C. difficile Laboratory-Identified Event Reporting

Area of Science:

• Infectious Diseases
• Clinical Diagnostics
• Healthcare Epidemiology

Background:

• Clostridium difficile infection (CDI) diagnosis relies on various laboratory methods.
• Enzyme immunoassay (EIA) and nucleic acid amplification (NAAT) are common diagnostic tools.
• Accurate CDI diagnosis is crucial for infection control and public health reporting.

Purpose of the Study:

• To evaluate the impact of diagnostic algorithms on hospital-onset CDI laboratory-identified (LabID) event standardized infection ratio (SIR).
• To assess the influence of using NAAT versus EIA in CDI diagnosis on reported infection rates.

Main Methods:

• An algorithm incorporating both enzyme immunoassay (EIA) and nucleic acid amplification (NAAT) was employed for CDI diagnosis.
• Hospital-onset CDI LabID event SIR was calculated and compared based on diagnostic methods.
• Data analysis focused on the differential impact of NAAT versus EIA on SIR.

Main Results:

• The utilization of NAAT in the diagnostic algorithm nearly doubled the hospital-onset CDI LabID event SIR compared to EIA alone.
• This suggests a significant increase in identified CDI cases when employing more sensitive NAAT methods.

Conclusions:

• The choice of diagnostic method for CDI substantially affects reported infection rates.
• Current risk adjustment strategies may not adequately account for the increased detection rates associated with NAAT.
• Modification of risk adjustment approaches is recommended to accurately reflect CDI epidemiology in healthcare settings.