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

<bold>Background: </bold>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).<bold>Objectives: </bold>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.<bold>Methods: </bold>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.<bold>Results: </bold>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.<bold>Conclusions: </bold>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. [ABSTRACT FROM AUTHOR]