[1] Tokyo Womens Med Univ, Dept Blood Purificat, Tokyo, Japan
[2] Arbor Res Collaborat Hlth, Ann Arbor, MI USA
[3] Shonantoubu Gen Hosp, Yokohama, Kanagawa, Japan
[4] Showa Univ, Sch Med, Dept Med, Div Nephrol, Tokyo 142, Japan
[5] Kyoto Univ, Grad Sch Med & Publ Hlth, Dept Healthcare Epidemiol, Kyoto, Japan