Author Affiliations: Institute of Social and Preventive Medicine, Lausanne, Switzerland (firstname.lastname@example.org).
To the Editor: The inverse association between urinary sodium excretion and CVD mortality found in a recent prospective cohort study1 challenges strategies to reduce salt intake in populations that are being implemented in an increasing number of countries.2 We would like to point out a few issues related to internal validity (potential exposure misclassification, confounding, and survival bias) and external validity (age of the participants in the study).
Bochud M, Guessous I, Bovet P. Urinary Sodium Excretion and Cardiovascular Disease Mortality. JAMA. 2011;306(10):1083-1087. doi:10.1001/jama.2011.1293