Bedside Risk Score Can Help Discriminate the Risk for MRSA Versus Other Pathogens

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of complicated skin and skin structure infections (cSSSI). Patients with MRSA require different empiric treatment that those with non-MRSA infections, yet no accurate tools exist to aid in stratifying the risk for a MRSA cSSSI. Zilberberg, et al. sought to develop a simple bedside decision rule to tailor empiric coverage more accurately.
The researchers conducted a large multicenter (N=62 hospitals) retrospective cohort study in a U.S.-based database between April 2005 and March 2009. All adult initial admissions with ICD-9-CM codes specific to cSSSI were included. Patients admitted with MRSA vs. non-MRSA were compared with regard to baseline demographic, clinical and hospital characteristics. We developed and validated a model to predict the risk of MRSA, and compared its performance via sensitivity, specificity and other classification statistics to the healthcare-associated (HCA) infection risk factors.
Of the 7,183 patients with cSSSI, 2,387 (33.2 percent) had MRSA. Factors discriminating MRSA from non-MRSA were age, African-American race, no evidence of diabetes mellitus, cancer or renal dysfunction, and prior history of cardiac dysrhythmia. The score ranging from 0 to 8 points exhibited a consistent dose-response relationship. A MRSA score of 5 or higher was superior to the HCA classification in all characteristics, while that of 4 or higher was superior on all metrics except specificity.
The researchers say that MRSA is present in one-third of all hospitalized cSSSI.  They conclude that a simple bedside risk score can help discriminate the risk for MRSA versus other pathogens with improved accuracy compared to the HCA definition. Their research was published in BMC Infectious Diseases. 

Reference: Zilberberg MD, et al. Development and validation of a bedside risk score for MRSA among patients hospitalized with complicated skin and skin structure infections. BMC Infectious Diseases 2012, 12:154 doi:10.1186/1471-2334-12-154