Article Text
Abstract
Introduction Global burdens of cardiovascular disease are increasing as populations age. Salt contributes to vascular risk by increasing blood pressure but there have been no reported estimates of its contribution to global and regional disease burdens.
Methods Using a comparative risk assessment framework we identified effects of salt on intermediate (systolic blood pressure (SBP)) and disease (stomach cancer (SC)) outcomes that met the WHO criteria for causality at the “probable” or “convincing” level. Effect sizes were taken from meta-analyses of cohort studies (SC, risk related to intakes) and of randomised controlled trials of sodium reduction (SBP, effect related to urinary sodium excretion). Effect modification by age (for SBP) was estimated by re-analysis of a meta-analysis data set. Relative effects in populations of African ancestry came from 2 randomised controlled trials.
Regional age and sex specific exposure levels were assessed from published and unpublished reports of 24 h urinary excretion (assumed to be 90% of intake). Work on methods for extending exposure estimates using dietary survey data are on-going. These inputs, together with regional SC incidence and SBP distributions will allow computation of attributable disease burdens.
Results For study years 1990 (2005) estimates of urinary sodium excretion were available for 36 (22) countries from 16 (13) GBD regions. Only 3 (4) were from nationally representative samples. Work on attributable burdens is on-going and will be presented.
Conclusion Estimating disease burdens attributable to higher than optimal salt intake will prove feasible. Uncertainty will be increased by the limitations of the available exposure data.