Research – National Costs Associated with Methicillin-susceptible and Methicillin-resistant S. aureus Hospitalizations in the United States, 2010–2014

Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have been associated with worse patient outcomes and higher costs of care than susceptible (MSSA) infections. However, the healthcare landscape has changed since prior studies found these differences, including widespread dissemination of community-associated strains of MRSA. Our objective was to provide updated estimates of the excess costs of resistant S. aureus infections.

We conducted a retrospective analysis using data from the National Inpatient Sample from the Agency for Healthcare Research and Quality for the years 2010 to 2014. We calculated costs for hospitalizations including MRSA– and MSSA–related septicemia and pneumonia infections, as well as MRSA– and MSSA–related infections from conditions classified elsewhere and of an unspecified site (“other infections”). Differences in the costs of hospitalization were estimated using propensity score adjusted mortality outcomes for 2010 through 2014.

In 2014, estimated costs were highest for pneumonia and sepsis-related hospitalizations. Propensity score-adjusted costs were significantly higher for MSSA–related pneumonia ($40,725 vs $38,561; p=0.045) and other hospitalizations ($15,578 vs $14,792; p<0.001) than for MRSA–related hospitalizations. Similar patterns were observed from 2010 to 2013, though crude cost differences between MSSA- and MRSA-related pneumonia hospitalizations rose from 25.8% in 2010 to 31.0% in 2014. MRSA-related hospitalizations had a higher adjusted mortality rate than MSSA-related hospitalizations.

Though MRSA infections had been previously associated with higher hospitalization costs, our results suggest that in recent years, costs associated with MSSA–related infections have converged with and may surpass costs of similar MRSA-related hospitalizations.