Impact of the COVID-19 pandemic on the incidence of surgical site infection after orthopaedic surgery: an interrupted time series analysis of the nationwide surveillance database in Japan

BACKGROUND: During the COVID-19 pandemic, hygiene awareness was increased in communities and hospitals. However, there is controversy regarding whether such circumstances affected the incidence of surgical site infections (SSIs) in the orthopaedic surgical field. AIM: To examine the impact of the COVID-19 pandemic on the incidence of SSIs after orthopaedic surgery. METHODS: The medical records of patients having undergone orthopaedic surgery were extracted from the nationwide surveillance database in Japan. The primary outcomes were the monthly incidences of total SSIs, deep or organ/space SSIs, and SSIs due to meticillin-resistant Staphylococcus aureus (MRSA). Interrupted time series analysis was conducted between pre-pandemic (January 2017 to March 2020) and pandemic (April 2020 to June 2021) periods. RESULTS: A total of 309,341 operations were included. Interrupted time series analysis adjusted for seasonality showed no significant changes in the incidence of total SSIs (rate ratio 0.94 and 95% confidence interval 0.98–1.02), deep or organ/space SSIs (0.91, 0.72–1.15), or SSIs due to MRSA (1.07, 0.68–1.68) along with no remarkable slope changes in any parameter (1.00, 0.98–1.02; 1.00, 0.97–1.02; and 0.98, 0.93–1.03, respectively). CONCLUSIONS: Awareness and measures against the COVID-19 pandemic did not markedly influence the incidence of total SSIs, deep or organ/space SSIs, or SSIs due to MRSA following orthopaedic surgery in Japan.