[1
]
Department of Health Statistics, School of Public Health, Fourth Military Medical
University, China.
[2
]
Department of Paediatrics, Tangdu Hospital, Fourth Military Medical University, China.
[3
]
Nautical and Aviation Medical Center, Navy General Hospital, China.
[4
]
Department of Health Statistics, School of Public Health, Fourth Military Medical
University, China. Electronic address: xuyongy@fmmu.edu.cn.
[5
]
Department of Health Statistics, School of Public Health, Fourth Military Medical
University, China. Electronic address: shanglei@fmmu.edu.cn.