Comparison of 2 Clostridium difficile surveillance methods: National Healthcare Safety Network's laboratory-identified event reporting module versus clinical infection surveillance.

OBJECTIVE: To determine whether the Centers for Disease Control and Prevention's National Healthcare Safety Network (NHSN) laboratory-identified (LabID) event reporting module for Clostridium difficile infection (CDI) is an adequate proxy measure of clinical CDI for public reporting purposes by comparing the 2 surveillance methods.
DESIGN: Validation study.
SETTING: Thirty New York State acute care hospitals.
METHODS: Six months of data were collected by 30 facilities using a clinical infection surveillance definition while also submitting the NHSN LabID event for CDI. The data sets were matched and compared to determine whether the assigned clinical case status matched the LabID case status. A subset of mismatches was evaluated further, and reasons for the mismatches were quantified. Infection rates determined using the 2 definitions were compared.
RESULTS: A total of 3,301 CDI cases were reported. Analysis of the original data yielded a 67.3% (2,223/3,301) overall case status match. After review and validation, there was 81.3% (2,683/3,301) agreement. The most common reason for disagreement (54.9%) occurred because the symptom onset was less than 48 hours after admission but the positive specimen was collected on hospital day 4 or later. The NHSN LabID hospital onset rate was 29% higher than the corresponding clinical rate and was generally consistent across all hospitals.
CONCLUSIONS: Use of the NHSN LabID event minimizes the burden of surveillance and standardizes the process. With a greater than 80% match between the NHSN LabID event data and the clinical infection surveillance data, the New York State Department of Health made the decision to use the NHSN LabID event CDI data for public reporting purposes.