1. Department of Epidemiology and Health Statistics, Xiangya School of Public HealthCentral South University Changsha Hunan China
2. Department of Mathematics and StatisticsMzuzu University Mzuzu Malawi
3. Department of Clinical Medicine, Mental Health Research SectionSaint John of God Community Services Mzuzu Malawi
4. OMNI Research Group, Department of Obstetrics and Gynecology, Faculty of MedicineUniversity of Ottawa Ottawa Ontario Canada
5. Ottawa Hospital Research InstituteClinical Epidemiology Program Ottawa Ontario Canada
6. School of Epidemiology, Public Health, and Preventive Medicine, Faculty of MedicineUniversity of Ottawa Ottawa Ontario Canada