Surgical volume reduction and the announcement of triage during the 1st wave of the COVID-19 pandemic in Japan: a cohort study using an interrupted time series analysis

Purpose The coronavirus disease (COVID-19) pandemic has caused unprecedented challenges for surgical staffs to minimize exposure to COVID-19 or save medical resources without harmful patient outcomes, in accordance with the statement of each surgical society. No research has empirically validated declines in surgical volume in Japan, based on the usage of surgical triage. We aimed to identify whether the announcement of surgical priorities by each Japanese surgical society may have affected the surgical volume decline during the 1st wave of this pandemic. Methods We extracted 490,719 available cases of patients aged > 15 years who underwent elective major surgeries between July 1, 2018, and June 30, 2020. After the categorization of surgical specialities, we calculated descriptive statistics to compare the year-over-year trend and conducted an interrupted time series analysis to validate the decline of each surgical procedure. Results Monthly surgical cases of eight surgical specialities, especially ophthalmology and ear/nose/throat surgeries, decreased from April 2020 and reached a minimum in May 2020. An interrupted time series analysis showed no significant trends in oncological and critical surgeries. Conclusion Non-critical surgeries showed obvious and statistically significant declines in case volume during the 1st wave of the COVID-19 pandemic according to the statement of each surgical society in Japan. Supplementary Information The online version contains supplementary material available at 10.1007/s00595-021-02286-6.