43: PREVALENCE, PREDICTORS AND OUTCOMES OF MRSA INFECTIONS IN PATIENTS HAVING MAJOR SURGICAL PROCEDURES

Abstract

Introduction: Major Operating room procedures (MORP) are frequently performed in hospitalized patients for a variety of causes and are associated with significant morbidity and mortality. Hospital-Acquired Methicillin Resistant Staphylococcus Aureus (HA-MRSA) is associated with severe and invasive disease, longer hospital stays, higher mortality, and higher healthcare costs. MRSA infection rates in hospitalized surgical patients and outcomes vary widely among reported single center studies. Methods: A retrospective analysis of the Nationwide Inpatient Sample (NIS) for the years 2009 and 2010 was used for the current study. The NIS is the largest all-payer hospital discharge database in the United States that is a part of the Healthcare Cost and Utilization Project sponsored by the Agency for Healthcare Research and Quality. All hospitalizations that underwent a MORP were selected for analysis. Occurrence of MRSA infection (ICD-9-CM code of 041.12), MRSA septicemia (038.12), and MRSA pneumonia (482.42) were identified from secondary diagnoses fields. Carrier/suspected carrier status of MRSA and personal history of MRSA were also identified. Patient and hospital-level factors associated with occurrence of MRSA were identified by a multivariable logistic regression model. Association between MRSA and outcomes including hospital length of stay (LOS) and in-hospital mortality (IHM) were examined by multivariable linear and logistic regression models respectively. Results: During the study period a total of 22,932,947 hospitalizations had an MORP. Among these, 0.84% had MRSA infection, 0.09% had MRSA septicemia, and 0.10% had methicillin resistant pneumonia due to staphylococcus aureus. MRSA was present in 1.03% of all hospitalizations that had a MORP. Carrier/suspected status of MRSA was present in 0.27% of all hospitalizations that had an MORP and personal history of MRSA was found in 0.19% of all hospitalizations. Amongst those that had at least one type of MRSA infection (n=235,636 hospitalizations), carrier/suspected MRSA status was present in 1.7% and personal history of MRSA was found in 2.9%. Those with MRSA had a higher co-morbid burden (mean of 3.1 co-morbid conditions) compared to those who did not have MRSA (mean of 1.6 conditions). The mean hospital LOS among those with MRSA was 14 days (5 days for those without MRSA). Hospital mortality rate for patients with MRSA was 3.7% (1.2% for those without MRSA). Factors that were associated with a significantly (p<0.05) higher odds for occurrence of MRSA event included female sex, race (black and native Americans compared to whites), emergency/urgent admission, increased co-morbid burden, uninsured patients, non-teaching hospitals, and small/medium hospitals (number of beds). Following adjustment for all other patient and hospital level confounding factors, occurrence of an MRSA event was associated with significantly longer hospital LOS (estimate is 0.68, p<0.01) and higher odds of IHM (OR=1.39, 95% CI=1.30 – 1.48, p<0.01) Conclusions: In this large retrospective study, hospitalized patients who underwent a major operating room procedure and developed an MRSA infection had a higher risk of mortality and increased hospital resource utilization. Certain predictors of MRSA infection are identified.