Geographical distribution of PRCA occurrence in Japan. The prefectural disparities in (A) the number of patients with PRCA registered in Ptosh and (B) the numbers of JSH hematologists. Although a regional PRCA incidence varies between 1.04 and 21.6 per million, it was not correlated with a hematologist density (Pearson’s product-moment correlations 0.0462; 95% CI, −0.244 to 0.329; P = .0758).