[1] Tokyo Med Univ, Dept Med Educ, Tokyo 1600023, Japan
[2] Teikyo Univ, Sch Med, Dept Hyg & Publ Hlth, Tokyo 173, Japan
[3] Tokyo Womens Med Univ, Inst Womens Hlth, Tokyo, Japan
[4] Jikei Univ, Sch Med, Tokyo, Japan
[5] Hokkaido Univ, Fac Med, Dept Med Educ, Sapporo, Hokkaido, Japan