Methods: We identified first admissions into a VA facility from January 1 2000 to July 1 2011, restricting our analysis to patients first admitted into a hospital after MRSA surveillance was initiated on October 1, 2007. Patients were included if they had an admission test and at least one additional test during their stay. Importation was defined by a positive MRSA surveillance test within 12 hours of admission, and acquisition was defined as a negative test within 12 hours of admission followed by a positive test. Primary outcome was NH transfer, with all other events censored. We classified MRSA colonization as either importation or acquisition, and ran a cox proportional hazard model, treating acquisition as a time-varying covariate. Because the time of first positive test is unlikely to coincide with the time of acquisition, we estimated acquisition time as the midpoint between the negative and positive test times. Baseline covariates included importation, gender and age.
Results: Included were 243,553 admissions with a total of 5,548 (2.3 %) transfers to NH, 12,399 (5.1 %) importations and 3,064 (1.3 %) acquisitions. Gender was not associated with NH transfer, but age was associated with increased risk of NH transfer (HR 1.36, 95% CI 1.25-1.49 for 55 age 70, and HR 1.84, 95% CI 1.68-2.01 for age 70). Additionally, importation (HR 1.19, 95% CI 1.09-1.31) and acquisition (HR 1.28, 95% CI 1.09-1.49) were associated with increased rate of NH transfer.
Conclusion: MRSA colonization is associated with increased risk of NH transfer following hospital admission. Additionally, acquisition of MRSA seems to result in a slightly elevated risk of NH transfer compared with those who are colonized at the time of hospital admission.
M. Jones, None
M. Rubin, None
M. Samore, None