Burden of meticillin-resistant Staphylococcus aureus infections at a Swiss University hospital: excess length of stay and costs q M. Macedo-Vin˜as a , G. De Angelis b , P. Rohner c , E. Safran c , A. Stewardson d , C. Fankhauser d , J. Schrenzel a, e , D. Pittet d , S. Harbarth a, d, * a Infectious Diseases Service, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland b Division of Infectious Diseases, Universita` Cattolica Sacro Cuore, Rome, Italy c Health-Economic Unit, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland d Infection Control Program, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland e Microbiology Laboratory, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland A RT I C L E I N F O Article history: Received 1 July 2012 Accepted 24 February 2013 Available online 19 April 2013 Keywords: Economics Epidemiology Health burden Meticillin-resistant Staphylococcus aureus Multistate modelling SUMM ARY Background: Meticillin-resistant Staphylococcus aureus (MRSA) infections increase hos- pital costs primarily by prolonging patient length of stay (LOS). Aim: To estimate the health-economic burden of MRSA infections at a Swiss University hospital using different analytical approaches. Methods: Excess LOS was estimated by: (i) multistate modelling comparing MRSA-infected and MRSA-free patients with MRSA infection as time-dependent exposure; (ii) matching MRSA-infected patients with a cohort of MRSA-uninfected patients. The economic impact was assessed by: (i) comparing cost estimates between MRSA-infected and MRSA-free patients and multiplying excess LOS by bed-day cost; (ii) comparing real costs between MRSA-infected and MRSA-colonized non-infected patients. Findings: The crude mean LOS was 37.3, 33.0 and 8.8 days for MRSA-infected, MRSA- colonized and MRSA-free patients, respectively. Excess LOS attributable to MRSA infection was 11.5 [95% confidence interval (CI): 7.9e15] or 15.3 days according to multistate modelling and matched analysis, respectively. The likelihood of discharge after MRSA infection was significantly reduced (adjusted hazard ratio: 0.69; 95% CI: 0.59e0.81). Average bed-day costs for MRSA-infected patients were 1.49- and 1.26-fold higher than for the general population hospitalized in acute wards and MRSA-colonized patients, respectively. MRSA infection resulted in an average additional cost of about 800 Swiss francs per day. Conclusions: This analysis emphasizes the financial impact of MRSA infections, demon- strates the importance of accounting for time-dependent bias and confirms that multistate modelling is a valid strategy for estimating excess LOS and costs after MRSA infection. ª 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved. q Presented in part at the International Conference on Prevention & Infection Control (ICPIC), June 2011, Geneva, Switzerland (abstract O89). * Corresponding author. Address: Infection Control Program, Geneva University Hospitals and Medical School, 4, rue Gabrielle-Perret-Gentil, CH-1211 Geneva 14, Switzerland. Tel.: þ41 22 372 3357; fax: þ41 22 372 3987. E-mail address: stephan.harbarth@hcuge.ch (S. Harbarth). Available online at www.sciencedirect.com Journal of Hospital Infection journal homepage: www.elsevierhealth.com/journals/jhin 0195-6701/$ e see front matter ª 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jhin.2013.02.015 Journal of Hospital Infection 84 (2013) 132e137