共 50 条
- [1] Independent and combined effects of sleep quality and night sleep duration on health-related quality of life in rural areas: a large-scale cross-sectional studyHEALTH AND QUALITY OF LIFE OUTCOMES, 2022, 20 (01)Liao, Wei论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaLiu, Xiaotian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaKang, Ning论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaWang, Lulu论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaZhai, Zhihan论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaYang, Jing论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaWu, Xueyan论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaMei, Yongxia论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaSang, Shengxiang论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaWang, Chongjian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaLi, Yuqian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Sch Pharmaceut Sci, Dept Clin Pharmacol, Zhengzhou, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China
- [2] Sleep duration in schooldays is associated with health-related quality of life in norwegian adolescents: a cross-sectional studyBMC PEDIATRICS, 2023, 23 (01)Grasaas, Erik论文数: 0 引用数: 0 h-index: 0机构: Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, Norway Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, Norway论文数: 引用数: h-index:机构:Haraldstad, Kristin论文数: 0 引用数: 0 h-index: 0机构: Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, Norway Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, NorwayHelseth, Solvi论文数: 0 引用数: 0 h-index: 0机构: Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, Norway Oslo Metropolitan Univ, Fac Hlth Sci, Dept Nursing & Hlth Promot, Oslo, Norway Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, NorwaySmastuen, Milada Cvancarova论文数: 0 引用数: 0 h-index: 0机构: Oslo Metropolitan Univ, Fac Hlth Sci, Dept Nursing & Hlth Promot, Oslo, Norway Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, Norway论文数: 引用数: h-index:机构:Mikkelsen, Hilde Timenes论文数: 0 引用数: 0 h-index: 0机构: Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, Norway Univ Agder, Fac Hlth & Sport Sci, Dept Hlth & Nursing Sci, Kristiansand, Norway
- [3] Sleep duration in schooldays is associated with health-related quality of life in norwegian adolescents: a cross-sectional studyBMC Pediatrics, 23 (1)Erik Grasaas论文数: 0 引用数: 0 h-index: 0机构: University in Agder,Department of Health and Nursing Science, Faculty of Health and Sport SciencesGudrun Rohde论文数: 0 引用数: 0 h-index: 0机构: University in Agder,Department of Health and Nursing Science, Faculty of Health and Sport SciencesKristin Haraldstad论文数: 0 引用数: 0 h-index: 0机构: University in Agder,Department of Health and Nursing Science, Faculty of Health and Sport SciencesSølvi Helseth论文数: 0 引用数: 0 h-index: 0机构: University in Agder,Department of Health and Nursing Science, Faculty of Health and Sport SciencesMilada Cvancarova Småstuen论文数: 0 引用数: 0 h-index: 0机构: University in Agder,Department of Health and Nursing Science, Faculty of Health and Sport SciencesSiv Skarstein论文数: 0 引用数: 0 h-index: 0机构: University in Agder,Department of Health and Nursing Science, Faculty of Health and Sport SciencesHilde Timenes Mikkelsen论文数: 0 引用数: 0 h-index: 0机构: University in Agder,Department of Health and Nursing Science, Faculty of Health and Sport Sciences
- [4] Health-Related Quality of Life and Its Related Factors in Survivors of Stroke in Rural China: A Large-Scale Cross-Sectional StudyFRONTIERS IN PUBLIC HEALTH, 2022, 10Mei, Yong-xia论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, Zhengzhou, Peoples R China Peoples Hosp Hebi, Hebi, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaZhang, Zhen-xiang论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaWu, Hui论文数: 0 引用数: 0 h-index: 0机构: Xinxiang Med Univ, Sch Publ Hlth, Xinxiang, Peoples R China Tianjin Med Univ, Sch Publ Hlth, Tianjin, Peoples R China Henan Prov Gen Med Educ & Res Ctr, Xinxiang, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaHou, Jian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, Zhengzhou, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaLiu, Xiao-tian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, Zhengzhou, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaSang, Sheng-xiang论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, Zhengzhou, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaMao, Zhen-xing论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, Zhengzhou, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaZhang, Wei-hong论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaYang, Dong-bin论文数: 0 引用数: 0 h-index: 0机构: Peoples Hosp Hebi, Hebi, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R ChinaWang, Chong-jian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, Zhengzhou, Peoples R China Zhengzhou Univ, Sch Nursing & Hlth, Zhengzhou, Peoples R China
- [5] Quality of life and sleep disturbances in Afghanistan: a large scale cross-sectional studyDISCOVER SOCIAL SCIENCE AND HEALTH, 2025, 5 (01):Neyazi, Ahmad论文数: 0 引用数: 0 h-index: 0机构: Afghanistan Ctr Epidemiol Studies, Herat 3001, Afghanistan Ghalib Univ, Fac Med, Herat, Afghanistan Kabul Univ Med Sci, Fac Med, Kabul, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanRahimi, Bilal Ahmad论文数: 0 引用数: 0 h-index: 0机构: Kandahar Univ, Fac Med, Dept Pediat, Kandahar, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanMohammadi, Abdul Qadim论文数: 0 引用数: 0 h-index: 0机构: Herat Reg Hosp, Dept Mental Hlth, Herat, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanArsin, Parwin论文数: 0 引用数: 0 h-index: 0机构: Afghanistan Ctr Epidemiol Studies, Herat 3001, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanAfzali, Habibah论文数: 0 引用数: 0 h-index: 0机构: Afghanistan Ctr Epidemiol Studies, Herat 3001, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanNeyazi, Mehrab论文数: 0 引用数: 0 h-index: 0机构: Afghanistan Med Students Assoc, Sci Res Comm, Herat, Afghanistan Herat Univ, Herat, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanHosaini, Sayed Farooq论文数: 0 引用数: 0 h-index: 0机构: Herat Univ, Fac Med, Dept Surg, Herat, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanSifat, Sifatullah论文数: 0 引用数: 0 h-index: 0机构: Dr Shams Ul Haq Kakar Comprehens Hlth Ctr, Kandahar, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanDaulati, Mohammad Naeem论文数: 0 引用数: 0 h-index: 0机构: Herat Reg Hosp, Sci Res Comm, Herat, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanQanawezi, Laila论文数: 0 引用数: 0 h-index: 0机构: Herat Reg Hosp, Dept Gynecol, Herat, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanSarem, Shararah论文数: 0 引用数: 0 h-index: 0机构: Herat Reg Hosp, Dept Gynecol, Herat, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, AfghanistanAmini, Parasto论文数: 0 引用数: 0 h-index: 0机构: Afghanistan Ctr Epidemiol Studies, Herat 3001, Afghanistan Afghanistan Ctr Epidemiol Studies, Herat 3001, Afghanistan
- [6] The association of sleep quality and night sleep duration with coronary heart disease in a large-scale rural populationSLEEP MEDICINE, 2021, 87 : 233 - 240Zhang, Bin论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaWang, Yan论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaLiu, Xiaotian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaZhai, Zhihan论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaSun, Jiaqi论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaYang, Jing论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaLi, Yuqian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Sch Pharmaceut Sci, Dept Clin Pharmacol, Zhengzhou, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaWang, Chongjian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China
- [7] Poverty and health-related quality of life: a cross-sectional study in rural ChinaHealth and Quality of Life Outcomes, 18Zhong Li论文数: 0 引用数: 0 h-index: 0机构: Huazhong University of Science and Technology,School of Medicine and Health Management, Tongji Medical CollegeLiang Zhang论文数: 0 引用数: 0 h-index: 0机构: Huazhong University of Science and Technology,School of Medicine and Health Management, Tongji Medical College
- [8] Poverty and health-related quality of life: a cross-sectional study in rural ChinaHEALTH AND QUALITY OF LIFE OUTCOMES, 2020, 18 (01)Li, Zhong论文数: 0 引用数: 0 h-index: 0机构: Huazhong Univ Sci & Technol, Tongji Med Coll, Sch Med & Hlth Management, 13 Hangkong Rd, Wuhan 430030, Hubei, Peoples R China Res Ctr Rural Hlth Serv, Key Res Inst Humanities & Social Sci Hubei Prov, Dept Educ, Wuhan 430030, Hubei, Peoples R China Huazhong Univ Sci & Technol, Tongji Med Coll, Sch Med & Hlth Management, 13 Hangkong Rd, Wuhan 430030, Hubei, Peoples R ChinaZhang, Liang论文数: 0 引用数: 0 h-index: 0机构: Huazhong Univ Sci & Technol, Tongji Med Coll, Sch Med & Hlth Management, 13 Hangkong Rd, Wuhan 430030, Hubei, Peoples R China Res Ctr Rural Hlth Serv, Key Res Inst Humanities & Social Sci Hubei Prov, Dept Educ, Wuhan 430030, Hubei, Peoples R China Huazhong Univ Sci & Technol, Tongji Med Coll, Sch Med & Hlth Management, 13 Hangkong Rd, Wuhan 430030, Hubei, Peoples R China
- [9] Association of nocturnal sleep duration and sleep midpoint with osteoporosis risk in rural adults: a large-scale cross-sectional studySleep and Breathing, 2023, 27 : 2191 - 2198Hongfei Zhao论文数: 0 引用数: 0 h-index: 0机构: College of Public Health,Department of Epidemiology and BiostatisticsLinghui Zhu论文数: 0 引用数: 0 h-index: 0机构: College of Public Health,Department of Epidemiology and BiostatisticsLin Fan论文数: 0 引用数: 0 h-index: 0机构: College of Public Health,Department of Epidemiology and BiostatisticsJing Yang论文数: 0 引用数: 0 h-index: 0机构: College of Public Health,Department of Epidemiology and BiostatisticsJian Hou论文数: 0 引用数: 0 h-index: 0机构: College of Public Health,Department of Epidemiology and BiostatisticsGongyuan Zhang论文数: 0 引用数: 0 h-index: 0机构: College of Public Health,Department of Epidemiology and BiostatisticsChongjian Wang论文数: 0 引用数: 0 h-index: 0机构: College of Public Health,Department of Epidemiology and BiostatisticsJun Pan论文数: 0 引用数: 0 h-index: 0机构: College of Public Health,Department of Epidemiology and Biostatistics
- [10] Association of nocturnal sleep duration and sleep midpoint with osteoporosis risk in rural adults: a large-scale cross-sectional studySLEEP AND BREATHING, 2023, 27 (06) : 2191 - 2198Zhao, Hongfei论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaZhu, Linghui论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaFan, Lin论文数: 0 引用数: 0 h-index: 0机构: Wenzhou Med Univ, Affiliated Hosp 2, Dept Orthopaed Surg, Yuying Childrens Hosp, Wenzhou, Zhejiang, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaYang, Jing论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaHou, Jian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaZhang, Gongyuan论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaWang, Chongjian论文数: 0 引用数: 0 h-index: 0机构: Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R ChinaPan, Jun论文数: 0 引用数: 0 h-index: 0机构: Wenzhou Med Univ, Affiliated Hosp 2, Dept Orthopaed Surg, Yuying Childrens Hosp, Wenzhou, Zhejiang, Peoples R China Zhengzhou Univ, Coll Publ Hlth, Dept Epidemiol & Biostat, 100 Kexue Ave, Zhengzhou 450001, Henan, Peoples R China