The attributable mortality, length of stay, and health care costs of methicillin-resistant Staphylococcus aureus infections in Singapore

Objectives

We used a multi-state model, which mitigates time-dependent bias, to estimate the mortality, length of stay (LOS), and costs of methicillin-resistant Staphylococcus aureus (MRSA) infections in Singapore.

Methods

We conducted a retrospective study in a hospital in Singapore from 2018 to 2022. Patients with MRSA infections were matched 1:1:3 to patients with MRSA colonization and patients without MRSA by age, gender, specialty, and intensive care admission, respectively. A multi-state model was used to derive excess LOS and mortality hazard ratios. The attributable cost of infections was estimated in 2022 Singapore dollars (SGDs) from the health care perspective.

Results

We matched 536 patients with MRSA infections to 536 patients with MRSA colonization, and to 1608 patients without MRSA. The excess LOS due to MRSA infection was 2.11 (95% confidence interval [CI] 2.05-2.17) days compared with MRSA colonization and 3.75 (95% CI 3.69-3.80) days compared with no MRSA, which translated to an excess cost of SGD $1825 and SGD $3238, respectively. Of the different MRSA infection types, pneumonia had the highest mortality risk (hazard ratio 4.13; 95% CI 2.28-7.50) compared with patients without MRSA.

Conclusions

MRSA infections increased hospital LOS and health care costs in Singapore. Our estimates can inform future economic analyses of management strategies against MRSA.