title: Leveraging ongoing research to evaluate the health impacts of South Africa's salt reduction strategy: a prospective nested cohort within the WHO-SAGE multicountry, longitudinal study.
abstract: Attempting to curb the rising epidemic of hypertension, South Africa implemented legislation in June 2016 mandating maximum sodium levels in a range of manufactured foods that contribute significantly to population salt intake. This natural experiment, comparing two African countries with and without salt legislation, will provide timely information on the impact of legislative approaches addressing the food supply to improve blood pressure in African populations. This article outlines the design of this ongoing prospective nested cohort study.
  
  
  
  Baseline sodium intake was assessed in a nested cohort of the WHO Study on global AGEing and adult health (WHO-SAGE) wave 2 (2014-2015), a multinational longitudinal study on the health and well-being of adults and the ageing process. The South African cohort consisted of randomly selected households (n=4030) across the country. Spot and 24-hour urine samples are collected in a random subsample (n=1200) and sodium, potassium, creatinine and iodine analysed. Salt behaviour and sociodemographic data are captured using face-to-face interviews, alongside blood pressure and anthropometric measures. Ghana, the selected control country with no formal salt policy, provided a nested subsample (n=1200) contributing spot and 24-hour urine samples from the SAGE Ghana cohort (n=5000). Follow-up interviews and urine collection (wave 3) in both countries will take place in 2017 (postlegislation) to assess change in population-level sodium intake and blood pressure.
  
  
  
  SAGE was approved by the WHO Ethics Review Committee (reference number RPC149) with local approval from the North-West University Human Research Ethics Committee and University of the Witwatersrand Human Research Ethics Committee (South Africa), and University of Ghana Medical School Ethics and Protocol Review Committee (Ghana). The results of the study will be published in peer-reviewed international journals, presented at national and international conferences, and summarised as research and policy briefs.
authors.affiliation: School of Medicine, University of Wollongong, Wollongong, New South Wales, Australia.
authors.forename: Karen
authors.initials: K
authors.lastname: Charlton
authors.affiliation: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors.forename: Lisa J
authors.identifier: 0000-0002-9762-4017
authors.initials: LJ
authors.lastname: Ware
authors.affiliation: School of Medicine, University of Wollongong, Wollongong, New South Wales, Australia.
authors.forename: Elias
authors.initials: E
authors.lastname: Menyanu
authors.affiliation: Department of Community Health, University of Ghana, Legon, Ghana.
authors.forename: Richard Berko
authors.initials: RB
authors.lastname: Biritwum
authors.affiliation: World Health Organization (WHO), Geneva, Switzerland.
authors.forename: Nirmala
authors.initials: N
authors.lastname: Naidoo
authors.affiliation: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors.forename: Chiné
authors.initials: C
authors.lastname: Pieterse
authors.affiliation: Global Clinical & Viral Laboratories, Durban, South Africa.
authors.forename: Savathree Lorna
authors.initials: SL
authors.lastname: Madurai
authors.affiliation: Centre of Excellence for Nutrition, North-West University, Potchefstroom, South Africa.
authors.forename: Jeannine
authors.initials: J
authors.lastname: Baumgartner
authors.affiliation: Chemical Pathology Unit, Department of Medical Laboratory Sciences, University of Ghana, Legon, Ghana.
authors.forename: George A
authors.initials: GA
authors.lastname: Asare
authors.affiliation: Vassar College, Poughkeepsie, New York, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Thiele
authors.affiliation: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.|MRC Research Unit for Hypertension and Cardiovascular Disease, North-West University, Potchefstroom, South Africa.
authors.forename: Aletta E
authors.initials: AE
authors.lastname: Schutte
authors.affiliation: World Health Organization (WHO), Geneva, Switzerland.|University of Newcastle Research Centre for Generational Health and Ageing, Newcastle, New South Wales, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Kowal
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging; D005191:Family Characteristics; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006293:Health Promotion; D006801:Humans; D006973:Hypertension / Q000453:epidemiology* / Q000517:prevention & control; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012959:Socioeconomic Factors; D017673:Sodium Chloride, Dietary / Q000009:adverse effects*; D013019:South Africa / Q000453:epidemiology
chemical_list: D017673:Sodium Chloride, Dietary
keywords: Salt reduction; Sub-Saharan Africa