Estimated medical costs of methicillin-resistant Staphylococcus aureus infection classified by polymerase chain reaction-based open reading frame typing in Japan

Tomokazu Shoji; Ryusei Muto; Ryoko Sakai; Hiroki Matsumura; Takashi Uchida; Fumihiko Kitta; Osamu Inoue; Keishi Kawata; Manabu Akazawa

doi:10.3934/microbiol.2022034

Estimated medical costs of methicillin-resistant Staphylococcus aureus infection classified by polymerase chain reaction-based open reading frame typing in Japan

AIMS Microbiol. 2022 Dec 19;8(4):528-543. doi: 10.3934/microbiol.2022034. eCollection 2022.

Authors

Tomokazu Shoji^{1

2

3}, Ryusei Muto², Ryoko Sakai², Hiroki Matsumura^{1

3}, Takashi Uchida^{3

4}, Fumihiko Kitta¹, Osamu Inoue³, Keishi Kawata¹, Manabu Akazawa²

Affiliations

¹ Department of Pharmacy, University of Yamanashi Hospital, 1110, Shimokato, Chuo, Yamanashi 409-3898, Japan.
² Department of Public Health and Epidemiology, Meiji Pharmaceutical University, 2-522-1, Noshio, Kiyose, Tokyo 204-8588, Japan.
³ Division of Infection Control and Prevention, University of Yamanashi Hospital, 1110, Shimokato, Chuo, Yamanashi 409-3898, Japan.
⁴ Department of Clinical Laboratory, University of Yamanashi Hospital, 1110, Shimokato, Chuo, Yamanashi 409-3898, Japan.

Abstract

This retrospective, observational cohort study investigated the economic impact of genotype by classifying methicillin-resistant Staphylococcus aureus (MRSA) by using the polymerase chain reaction-based open reading frame typing (POT) method. Using administrative claims and bacteriological data for April 2016 to March 2021 from the University of Yamanashi Hospital, we ascertained the POT1 numbers and classified MRSA as either "hospital-derived" or "community-derived". We defined MRSA-associated medical practices and estimated the associated medical costs. After applying inverse probability of treatment weighting (IPTW)-based adjustment for patient characteristics between the two groups, we estimated the differences in medical costs during the "total therapy period" (defined as the interval from specimen submission to Day 42 after the susceptibility report) and the "definitive therapy period" (defined as the interval from susceptibility reporting to Day 42). Among the 135 MRSA-infected patients, 54 and 81 were classified as having hospital-derived and community-derived MRSA infections, respectively. Significant differences in patient characteristics were observed with regard to age (p = 0.0478), sex (p = 0.0422), surgery (p = 0.0349), chemotherapy (p = 0.0457) and immunosuppressive drug use (p = 0.0222). The median duration of the definitive therapy was 29 and 27 days, and the mortality rate during this period was 11% and 5% for the hospital-derived and community-derived types, respectively. After IPTW-based adjustment, the medical costs for the total therapy period were 324,480 and 296,462 Japanese yen (JPY) per patient for the hospital-derived and community-derived types, respectively, whereas the medical costs for the definitive therapy period were 279,635 and 256,542 JPY per patient for the hospital-derived and community-derived types, respectively. No statistically significant difference was detected (p = 0.5813 and p = 0.6355, respectively). In this study, MRSA healthcare costs were compared according to the POT scores, and no statistically significant differences were observed between hospital-derived and community-derived MRSA infections.

Keywords: MRSA; PCR-based open reading frame typing; administrative claim database; healthcare cost; inverse probability of treatment weighting.