Impact of increased reimbursement for ambulance transportation on hospital acceptance in Japan: a difference-in-difference study

Objective Emergency medical services (EMS) often face difficulties in finding accepting hospitals in Japan. The universal medical insurance system in Japan increased the reimbursement for ambulance transportation acceptance at night, and on Sundays and holidays from 1 April 2016. This study investigated the effect of the reimbursement increase on the number of EMS calls, and transportation time from arrival at the scene to arrival at the hospital.Design A difference-in-difference study. The treatment group consisted of people who called an ambulance at night while the control group consisted of people who called an ambulance during the daytime.Setting The national ambulance records of the Fire and Disaster Management Agency in Japan from 1 April 2015 to 31 December 2016.Participants 7 625 463 ambulance dispatches were eligible for inclusion.Primary and secondary outcome measures The changes in EMS calls, transportation time and the number of ambulance transports per 1000 population in one month in a comparison of daytime and night-time transport.Results The treatment effect (night-time vs daytime) on the number of EMS calls was -0.013 (95% CI, -0.023 to -0.004), which was significant. The transportation time decreased slightly by 0.080 min (95% CI, -0.157 to -0.004). No impact was observed on the number of ambulance transports per 1000 population per month (0.00; 95% CI, -0.008 to 0.002).Conclusion An increase in reimbursement for ambulance transportation acceptance was associated with a decrease in the number of EMS calls. Further strategies for decreasing the number of EMS calls are needed to avoid delays in the treatment of emergency patients with critical illness.