Determining an Effective Measure of Testing for MRSA Colonization for Timely Placement in Appropriate Isolation Precautions.

Abstract

Background/Objectives: Patients are increasingly being admitted to hospitals colonized with vancomycin resistant Enterococcus (VRE). Many hospitals are evaluatingmethods to screen patients for VRE, particularly in intensive care units. This study sought to evaluate the economic implications of VRE screening using different culture and polymerase chain reaction (PCR) methods. Methods: We used decision analysis to model VRE screening using two chromogenic media (CM), one PCR, and one traditional culture approach.We alsomodeled a no screening strategy and a hypothetical perfect screen for comparison. The model estimated the cost and outcome implications of alternative methods of screening for VRE in the ICU setting and took into account spread of VRE, spread of vancomycin resistance, and whether hospitals were prepared to act immediately upon screening results. Outcomes included correct classification, unnecessary isolation costs, unnecessary infection costs, and total costs. Sensitivity analysis tested main model parameters. Results: Baseline analysis assumed: 1) a 17% colonization rate, 2) only patients with a positive screen were isolated, 3) 18 hours passed before action was taken on screening results, and 5) no patients were decolonized. The CM approach was associated with the highest combined rates of correct classification (99.7% and 99.2% for CM versus 93.4% for PCR and 77.1% for traditional culture) and positive predictive value (PPV) (99.0% and 98.5% for CM, 72.6% for PCR, and 42.0% for traditional culture). CM was also associated with lower unnecessary isolation costs per patient than PCR ($16.80 and $25.20 for CM, $675 for PCR, and $1,962 for traditional culture) and lower unnecessary infection costs ($3.42 and $11.79 for CM, $6.09 for PCR, and $30.43 for traditional culture). Conclusions: For hospitals considering a screening strategy for VRE in the intensive care unit, a CM approach appears to offer the highest rates of PPV and correct classification, and lowest overall unnecessary isolation and infection costs under baseline assumptions. Hospitals also need to weigh other factors such as time to action and isolation costs.