Author Affiliation: Department of Clinical Pharmacology, Bispebjerg University Hospital, Bispebjerg Bakke, Copenhagen, Denmark.
One justification for the repeated analysis of the Third National Health and Nutrition Examination Survey (NHANES III)1 is that the original analysis2 only used 1-day dietary recall data to estimate sodium intake. According to the authors, a single dietary recall estimation of salt intake is insufficient compared with a method based on 2 estimations. However, Caggiula et al3 found that the difference between a single and the average of 2 dietary recall estimations was minimal, but that the estimation by both recall methods was significantly smaller than the 24-hour urine sodium excretion (approximately 60 mEq/L [to convert to mmol/L, multiply by 1.0]). Consequently, the major difference is not between different recall methods but between dietary sodium recall and urine sodium excretion, the latter being considered the gold standard. However, to evaluate the quantitative significance of the method used by Yang et al1 to correct sodium intake, which they based on only 7.2% of the participants, it would be important for the authors to provide the number and percentage of participants changing sodium intake quartile as a result of this correction.
Jürgens G. Method of Estimating Sodium Intake and Its Possible Influence on NHANES III Outcome. Arch Intern Med. 2011;171(22):2063-2064. doi:10.1001/archinternmed.2011.590