Evaluation of the Positive Predictive Value of Rapid Assays Used by Clinical Laboratories in Minnesota for the Diagnosis of Cryptosporidiosis.

We evaluated the positive predictive value (PPV) of rapid assays used by clinical laboratories in Minnesota to diagnose cryptosporidiosis. The overall PPV was 56% for rapid assays versus 97% for nonrapid assays; clinicians and laboratorians need to be aware of the low PPV of rapid assays when diagnosing cryptosporidiosis.