Opioid prescription status around surgery, bone metastasis, or death events among patients with breast cancer in Japan: an analysis of the Japanese public health insurance comprehensive claims database (the National Database).

Objective: To investigate the opioid prescription status around clinical events among patients with breast cancer in Japan using a comprehensive claims database.

Methods: This was a retrospective cohort study using the National Database (April 2009-March 2020). The target patients had a first breast cancer diagnosis in April 2010 or later. The percentages of patients prescribed opioids before and after surgery, before and after bone metastasis, and before death with a breast cancer diagnosis in the same month were analyzed by month and by clinical facility characteristics and location.

Results: We identified 1 085 388 target patients, including 216 503, 72 645, and 70 832 patients with data for the events of surgery, bone metastasis, and death, respectively. The percentage of patients prescribed opioids in the month of surgery was the highest of the entire study period at ≥70%. The percentage of patients prescribed opioids increased before bone metastasis, peaked 1 month later, and decreased thereafter while remaining higher than that before the event. The percentage of patients who were prescribed opioids before death increased over time, peaking at 33.4% 1 month before death. Prescriptions differed by facility characteristics and facility location around surgery; no differences by facility characteristics, including location, were noted around the other events. The percentage of patients prescribed opioids was consistently lower than that reported in other countries for all events.

Conclusions: We showed the opioid prescription status around clinical events, including some distinct patterns depending on facility characteristics for the period around surgery, among patients with breast cancer in Japan.