Gatekeeping function of primary care physicians under Japan's free-access system: a prospective open cohort study involving 14 isolated islands

Background. Gatekeeping is important for strong primary care and cost containment. Under Japan's free-access system, patients can access any medical institution without referral, which makes it difficult to evaluate the gatekeeping function of primary care physicians (PCPs). Objectives. To examine the gatekeeping function of PCPs in Japan, we compared the frequencies of visits to primary care clinics, referrals to advanced care and hospitalizations between 14 remote islands and a nationwide survey. Methods. This study was a prospective, open cohort study involving 14 isolated islands (12 238 inhabitants) in Okinawa, Japan. Participants were all patients who visited the clinics on these islands in 1 year. Main outcome measures were the incidence of on-island clinic visits and referrals to off-island advanced care. Results. There were 54 741 visits to the islands' clinics with 2045 referrals to off-island medical facilities, including 549 visits to emergency departments and 705 hospitalizations. The age- and sex-standardized incidences of healthcare use per 1000 inhabitants per month were: 360.0 (95% confidence interval: 359.9 to 360.1) visits to primary care clinics, 11.6 (11.0 to 12.2) referrals to off-island hospital-based outpatient clinics, 3.3 (2.8 to 5.2) visits to emergency departments and 4.2 (3.1 to 5.2) hospitalizations. Comparison with the nationwide survey revealed a lower incidence of visits to hospital-based outpatient clinics in this study, while more patients had visited PCPs. Conclusions. The lower incidence of visits to secondary care facilities in this study might suggest that introduction of a gatekeeping system to Japan would reduce the incidence of referral to advanced care.