1. Department of Epidemiology and Biostatistics, School of Public Health, Harbin Medical University, Harbin 150086, P.R. China
2. Department of Gynecology Oncology, The Affiliated Tumor Hospital of Harbin Medical University, Harbin 150086, P.R. China
3. Harbin Medical University, Harbin 150086, P.R. China
4. Department of Biostatistics, University of Washington, Seattle 96596, WA, U.S.A
5. Key Laboratory of Cardiovascular Medicine Research (Harbin Medical University), Ministry of Education, Harbin 150086, P.R. China