Predictive value and cost-effectiveness analysis of a rapid polymerase chain reaction for preoperative detection of nasal carriage of Staphylococcus aureus

OBJECTIVE: To determine the accuracy and cost-effectiveness of a polymerase chain reaction (PCR) for detecting nasal carriage of Staphylococcus aureus directly from clinical specimens. CROSS-SECTIONAL STUDY: This occurred in a tertiary-care hospital in Cleveland, Ohio, and included 239 consecutive patients who were scheduled for a cardiothoracic surgical procedure. Conventional cultures and a PCR for S. aureus from nasal swabs were used as measurements. COST-EFFECTIVENESS ANALYSIS: Data sources were market prices and Bureau of Labor Statistics. The time horizon was the maximum period for availability of culture results (3 days). Interventions included universal mupirocin therapy without testing; initial therapy, with termination if PCR negative (treat-PCR); initial therapy, with termination if culture negative (treat-culture); treat PCR-positive carriers (PCR-guided treatment); and treat culture-positive carriers (culture-guided treatment). The perspective was institutional and costs and the length of time to treatment were outcome measures. RESULTS: Sixty-seven (28%) of the 239 swabs grew S. aureus. Rapid PCR was 97.0% sensitive and 97.1% specific for the detection of S. aureus. For populations with prevalences of nasal S. aureus carriage of up to 50%, the PCR assay had negative predictive values of greater than 97%. PCR-guided treatment had the lowest incremental cost-effectiveness ratio ($1.93 per additional day compared with the culture strategy). Among immediate treatment strategies, treat-PCR was most cost-effective. The universal therapy strategy cost $38.19 more per additional day gained with carrier identification compared with the PCR strategy. CONCLUSION: Rapid real-time PCR is an accurate, rapid, and cost-effective method for identifying S. aureus carriers for preoperative intervention.