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Racial Disparities in Invasive Methicillin-Resistant Staphylococcus Aureus Infections, 2005-2012

Monday, June 15, 2015: 5:00 PM
Back Bay A, Sheraton Hotel
Nicole R Gualandi , Centers for Disease Control and Prevention, Atlanta, GA
Yi Mu , Centers for Disease Control and Prevention, Atlanta, GA
Ghinwa Dumyati , Rochester Emerging Infections Program, Rochester, NY
Lee Harrison , Johns Hopkins University School of Public Health, Baltimore, MD
Lindsey Lesher , Minnesota Department of Health, St. Paul, MN
Joelle Nadle , California Emerging Infections Program, Oakland, CA
Sue Petit , Connecticut Department of Public Health, Hartford, CT
Susan M. Ray , Emory Univsersity School of Medicine, Decatur, GA
Claire Reisenauer , Colorado Department of Public Health and Environment, Denver, CO
William Schaffner , Tennessee Department of Health, Nashville, TN
John Townes , Oregon Health and Science University, Portland, OR
Marian McDonald , Centers for Disease Control and Prevention, Atlanta, GA
Isaac See , Centers for Disease Control and Prevention, Atlanta, GA
Audio File Recorded Presentation

BACKGROUND:  Rates of invasive infections due to methicillin-resistant Staphylococcus aureus among blacks in the U.S. are significantly higher than among whites. We investigated whether recent declines in incidence of invasive MRSA have affected racial differences in MRSA rates.

METHODS:  Data were obtained from active, population-based surveillance for invasive MRSA (isolated from a normally sterile body site) in selected areas across 9 states from 2005-2012. Cases were classified as hospital-onset (HO, culture >3 days after admission), healthcare-associated community onset (HACO, culture ≤3 days after admission and dialysis, hospitalization, surgery, or long term care residence within 1 year prior), or community-associated (CA, when neither HO nor HACO criteria are met). Patient data, including race, were obtained via retrospective chart review. Missing race (9% of cases) was imputed based on distribution of known race by age, gender, and state. Poisson and negative binomial regression models were used to evaluate the adjusted rate ratio (aRR) of MRSA in black patients (versus in white patients) controlling for age, gender, and temporal trends. To determine whether racial differences in incidence rates might be related to differences in access to care we examined incidence rates among chronic dialysis patients (an insured population with frequent healthcare encounters) by race. Analyses were limited to black and white race as these races comprised the majority (96%) of MRSA cases under surveillance.

RESULTS:  From 2005-2012, invasive MRSA rates significantly decreased for HO and HACO, although not CA infections. Despite these decreases, blacks had higher incidence rates for HO (aRR: 2.3; 95% CI: 1.7-3.3), HACO (aRR: 3.1; 95% CI: 2.3-4.3), and CA (aRR: 2.2; 95% CI: 1.7-2.7) MRSA compared to whites. These racial differences did not significantly change over time. Limiting the analysis to chronic dialysis patients reduced, but did not entirely eliminate, the higher HACO MRSA rates among blacks (aRR: 1.3; 95% CI: 1.3-1.4); these racial differences did not significantly change over time despite overall decreases in MRSA rates among dialysis patients.

CONCLUSIONS: Recent reductions in healthcare-associated MRSA infections have not affected racial differences in MRSA rates between 2005-2012, though adjustments for access to care explained some of the racial variation. Rates of invasive infections due to MRSA among blacks in the U.S. remain significantly higher than among whites. Improved understanding of the underlying causes of these differences and prevention strategies targeting these causes are needed to reduce racial disparities in MRSA infections.

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