Burden of meticillin-resistant Staphylococcus aureus infections at a Swiss University hospital: excess length of stay and costs

Abstract

Meticillin-resistant Staphylococcus aureus (MRSA) infections increase hospital costs primarily by prolonging patient length of stay (LOS). To estimate the health-economic burden of MRSA infections at a Swiss University hospital using different analytical approaches. 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. 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): 7.9-15] 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: 0.59-0.81). 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. This analysis emphasizes the financial impact of MRSA infections, demonstrates 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.