National costs associated with methicillin-susceptible and methicillin-resistant staphylococcus aureus hospitalizations in the United States, 2010-2014

Background. Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have been associated with worse patient outcomes and higher costs of care than methicillin-susceptible (MSSA) infections. However, since prior studies found these differences, the healthcare landscape has changed, including widespread dissemination of community-associated strains of MRSA. We sought to provide updated estimates of the excess costs of MRSA infections. Methods. We conducted a retrospective analysis using data from the National Inpatient Sample from the Agency for Healthcare Research and Quality for the years 2010-2014. We calculated costs for hospitalizations, including MRSA- A nd MSSA-related septicemia and pneumonia infections, as well as MRSA- A nd 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 2010-2014. Results. 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 = .045) and other hospitalizations ($15 578 vs $14 792; P < .001) than for MRSA-related hospitalizations. Similar patterns were observed from 2010 to 2013, although crude cost differences between MSSA- A nd MRSA-related pneumonia hospitalizations rose from 25.8% in 2010 to 31.0% in 2014. Compared with MSSA-related hospitalizations, MRSA-related hospitalizations had a higher adjusted mortality rate. Conclusions. Although 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 MRSArelated hospitalizations.