Toxin assay is more reliable than ICD-9 data and less time-consuming than chart review for public reporting of Clostridium difficile hospital case rates.

OBJECTIVE: Clostridium difficile-associated disease (CDAD) is common and has a 6.1% mortality. Governmental agencies have recommended surveillance, but reporting increases health care costs. We sought to identify a reliable method of reporting CDAD that will not significantly increase health care costs.
METHODS: Patients were identified via database query for International Statistical Classification of Diseases and Related Health Problems, 9th Edition (ICD-9) codes and C. difficile toxin positivity. All identified patients underwent a chart review, which was used to determine the accuracy of the database query methods. Methods of determining whether CDAD was acquired at the reporting institution were studied, and time required to perform each method was measured.
RESULTS: The toxin assay reported 96.1% (369/384) of cases and had a positive predictive value of 100%. No difference was found in comparison of the toxin assay case rate of 15.7 per 1000 discharged patients to the rate of 16.3 identified by chart review (P = 0.440; 95% confidence interval [CI], 14.1-17.4), whereas the ICD-9 method was found to be significantly different by reporting 116.1% (446/384) of cases for a case rate of 19.0 per 1000 discharges (P = 0.001; 95% CI, 17.3-20.8). The time for data extraction via the toxin assay method required only 842 minutes, while the chart review method consumed 21,899 minutes.
CONCLUSION: A positive C. difficile toxin assay accurately reports the institutional incidence of disease and is more reliable than ICD-9 query. This process can be instituted at a fraction of the cost of the standard chart review, and enables governmental agencies to inexpensively add CDAD to their list of reportable diseases.