International Centre for Evidence in Disability, Department of Population Health, London School of Hygiene & Tropical Medicine, London, United KingdomCentre for Evaluation, London School of Hygiene & Tropical Medicine, London, United KingdomMRC/ UVRI & LSHTM Uganda Research Unit, Entebbe, UgandaDepartment of Global Health and Development, London School of Hygiene & Tropical Medicine, London, UKSchool of Public Health, Makerere University, Kampala, UgandaAmref Health Africa in Uganda, Kampala, UgandaInternational Statistics and Epidemiology Group, London School of Hygiene & Tropical Medicine, London, United Kingdom.Division of Physiotherapy, Department of Health and Rehabilitation Sciences, Stellenbosch University, Cape Town, South Africa.