Physician scarcity is a predictor of further scarcity in US, and a predictor of concentration in Japan

Objectives: To assess the effects of geographic diffusion of physicians from medically oversupplied toward undersupplied areas driven by economic competition among physicians and political interventions in Japan and US. Methods: A quantitative evaluation of physician workforce changes at the community level between 1980 and 2005, using municipality-based (Japan) and county-based (US) census data. Results: The overall number of physicians per 100,000 population (physician-to-population ratio: PPR) increased from 130 to 203 in Japan and 158 to 234 in US. In this context, a higher proportion (30.1%) of the quintile communities with lowest PPRs in 1980 has further decreased their PPRs in US than in Japan (21.6% in 2005). In multivariate analysis low PPR was a positive predictor of PPR decrease in the US communities (odds ratio 1.26; 95% confidence interval 1.01-1.58), while it was a negative predictor in Japanese communities (0.69: 0.57-0.83). Conclusions: Physician scarcity is associated with further scarcity in US communities, while scarcity is associated with recovery from scarcity in Japanese communities. Competition-based physician diffusion strategies and various interventions to address the maldistribution of physicians apparently have not worked effectively in US compared with Japan. (C) 2009 Elsevier Ireland Ltd. All rights reserved.