title: Association between salt and hypertension in rural and urban populations of low to middle income countries: a systematic review and meta-analysis of population based studies.
abstract: OBJECTIVE
  The prevalence of hypertension, the greatest contributor to mortality globally, is increasing in low-and-middle income countries (LMICs). In urban regions of LMICs, excessive salt intake is associated with increased risk of hypertension. We aimed to determine whether this is the case in rural regions as well.
  
  
  METHODS
  We performed a meta-analysis of studies in rural and urban areas of LMICs in which the association of salt and hypertension were assessed using multivariable models.
  
  
  RESULTS
  We identified 18 studies with a total of 134,916 participants. The prevalence of high salt intake ranged from 21.3% to 89.5% in rural and urban populations. When salt was analysed as a continuous variable, a greater impact of salt on hypertension was found in urban (n=4) (pooled effect size (ES) 1.42, 95% CI 1.19, 1.69) than in rural populations (n=4) (pooled ES 1.07, 95% CI 1.04, 1.10, p for difference <0.001). In studies where salt was analysed continuously, a greater impact of salt on hypertension was observed in lean rural populations (BMI <23 kg/m2) than in non-lean rural populations (BMI >=23 kg/m2, p for difference <0.001).
  
  
  CONCLUSIONS
  The prevalence of high salt intake is similar in rural and urban regions. Excessive salt intake has a greater impact on the prevalence of hypertension in urban than rural regions. BMI appears to modify the relationship between salt and hypertension in rural populations.
authors.affiliation: Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Melbourne, Australia. Email: asvini.subasinghe@gmail.com.
authors.forename: Asvini K
authors.initials: AK
authors.lastname: Subasinghe
authors.affiliation: Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Melbourne, Australia.
authors.forename: Simin
authors.initials: S
authors.lastname: Arabshahi
authors.affiliation: Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Melbourne, Australia.
authors.forename: Doreen
authors.initials: D
authors.lastname: Busingye
authors.affiliation: Department of Physiology, Monash University, Melbourne, Australia.
authors.forename: Roger G
authors.initials: RG
authors.lastname: Evans
authors.affiliation: Department of Nutrition and Dietetics, Monash University, Melbourne, Australia.
authors.forename: Karen Z
authors.initials: KZ
authors.lastname: Walker
authors.affiliation: Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Melbourne, Australia.
authors.forename: Michaela A
authors.initials: MA
authors.lastname: Riddell
authors.affiliation: Department of Medicine, School of Clinical Sciences at Monash Health, Monash University, Melbourne, Australia.|Florey Neuroscience Institutes, Heidelberg, Victoria, Australia.
authors.forename: Amanda G
authors.initials: AG
authors.lastname: Thrift
mesh_terms: D015984:Causality; D003906:Developing Countries / Q000706:statistics & numerical data*; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D015994:Incidence; D011203:Poverty; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*; D014505:Urban Population / Q000706:statistics & numerical data*
chemical_list: D017673:Sodium Chloride, Dietary