Length of stay, hospitalisation costs and in-hospital mortality of methicillin-susceptible and methicillin-resistant Staphylococcus aureus bacteremia in Japan.

OBJECTIVES

To examine the length of stay, hospitalisation costs and case fatality of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA) bacteremia in Japan.

STUDY

DESIGN

Retrospective cohort study. Patients with a diagnosis of S. aureus bacteremia who were admitted to a tertiary care hospital (the National Centre for Global Health and Medicine [NCGM]) in Tokyo, Japan, between 1st January 2016 and 31st December 2020 were included in the study.

METHODS

We combined Japan Nosocomial Infections Surveillance data and Diagnosis Procedure Combination data at NCGM from 2016 to 2020. The data were stratified into MSSA and MRSA groups. Length of stay (LoS), LoS after submission of a blood culture specimen (LoS-after), hospitalisation cost, hospitalisation costs per day and clinical outcome were compared after propensity score matching.

RESULTS

Median LoS was 46 (interquartile range [IQR] 28.5-64.5) days in the MSSA group and 66 (IQR 40-91) days in the MRSA group (P = 0.020). Median LoS-after was 38 (IQR 25-62.5) days and 45 (IQR 24-63) days (P = 0.691) in the MSSA and MRSA groups, respectively. Median hospitalisation cost was significantly higher in the MRSA group (26,035 [IQR 18,154-47,362] USD) than in the MSSA group (19,823 [IQR 13,764-32,042] USD) (P = 0.036), but cost per day was not (MRSA: 528.9 [IQR 374.9-647.4] USD; MSSA: 455.6 [IQR 359.2-701.7] USD; P = 0.990). Case fatality rate was higher in the MRSA group than in the MSSA group (22/60 vs 9/60, P = 0.012).

CONCLUSIONS

Patients with MRSA bacteremia had longer LoS and higher costs than those with MSSA bacteremia. However, LoS-after and hospitalisation costs per day were not different. The longer LoS of patients in Japan compared with other countries might contribute to the higher disease burden of S. aureus bacteremia in Japan.