PURE Study (O'Donnell et al, NEJM 2014) Sodium exposure measure weak Single morning void Kawasaki formula over-estimates Na level in non-Asians Strong differences by country/region 17 countries – did not control for differences Extremely heterogeneous population Strong differences by baseline CVD and risk factors Inadequate control for confounding Potential for much residual confounding Large study size does not imply accuracy Can have small confidence interval for biased estimate
{}