Healthcare-associated methicillin-resistant Staphylococcus aureus infections increase the risk of post-dishcarge mortality
While many studies have estimated the impact of healthcare-associated methicillin resistant Staphylococcus aureus (MRSA) infections (MRSA HAIs) on mortality during the initial hospital stay, little is known about the long-term risk of death in these patients. The purpose of this study was to quantify the effect of MRSA HAIs on mortality after discharge from the hospital.
Our study cohort consisted of patients with an inpatient admission within the US Department of Veterans Affairs (VA) system between 10/1/2007 and 11/30/2010. Of these patients, we identified those with an MRSA HAI from microbiology reports in the VA electronic medical record. MRSA HAIs were defined as positive clinical cultures for MRSA between 48 hours after admission and 48 hours after discharge. Because microbiology data was insufficient to distinguish between MRSA infection and colonization, in a secondary analysis, we categorized MRSA HAIs into bloodstream and non-bloodstream since positive MRSA cultures from blood were most likely infections. We constructed multivariable Cox proportional hazards regressions to assess the impact of MRSA HAIs on post-discharge mortality in the 365 days following discharge using both the full cohort and a propensity score-matched subsample. Finally, we generated a mortality estimate for each of the 123 VA hospitals represented in our data to evaluate inter-facility variability.
In our analysis cohort of 369,743 inpatients, MRSA HAIs were recorded in 3,599 (1.0%) patients. We found that MRSA HAIs resulted in an increased risk of post-discharge mortality both in the full cohort (HR=1.42, p<0.001) and in the subset of propensity score-matched patients (HR=1.37, p<0.0001). Similarly, the risk of post-discharge mortality was elevated in patients with MRSA bloodstream HAIs (HR=1.61, p<0.001 full cohort; HR=1.72, p<0.001 propensity score-matched subset). In addition, there was considerable variation in estimates across facilities (Figure 1).
We found that MRSA HAIs significantly elevate the long-term risk of mortality. These results underscore the importance of infection prevention efforts in the hospital.
R. E. Nelson,
M. Jones, None
M. Samore, None
M. Rubin, None