Economic and clinical impact of nosocomial meticillin-resistant Staphylococcus aureus infections in Singapore: a matched case-control study

Abstract

We performed a prospective matched case-control study, with six-month follow-up for discharged subjects, to evaluate the direct clinical and financial impact of nosocomial meticillin-resistant Staphylococcus aureus (MRSA) infections in Singaporean hospitals. Consecutive nosocomial MRSA-infected cases at both tertiary public sector hospitals in Singapore were matched for age, specialty service, major surgical procedure (if applicable) and Charlson comorbidity index with up to two non-infected controls each. Chart reviews and subject interviews were performed during hospitalisation and also upon six months post-discharge for survivors. The outcomes analysed were: mortality, length of hospitalisation (LOS), healthcare-associated financial costs, and health-related quality of life. The last was evaluated via an interviewer-administered EuroQol-5D questionnaire on discharge, with conversion to a single health state summary index. Attributable outcomes were ascertained by conditional logistic and linear regression. There were 181 cases and 351 controls. MRSA infection was independently associated with in-hospital death [14.4% vs 1.4%; odds ratio (OR): 5.54; 95% confidence interval (CI): 1.63-18.79, P=0.006], longer LOS (median of 32 days vs 7 days; coefficient: 1.21; 95% CI: 1.02-1.40, P<0.001), higher hospitalisation costs (median of US$18,129.89 vs US$4,490.47; coefficient: 1.14; 95% CI: 0.93-1.35; P<0.001), higher post-discharge healthcare-associated financial costs (median of US$337.24 vs US$259.29; coefficient: 0.39; 95% CI: 0.06-0.72; P=0.021), and poorer health-related quality of life (coefficient: -0.14; 95% CI: -0.21 to -0.08; P<0.001). Outcomes were not significantly different between both hospitals. The attributable individual, institutional and societal impact of MRSA infections is considerable in Singapore. Preventing such infections will result in substantial improvements in patient outcomes and healthcare delivery.