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Subgroup Results in the DASH-Sodium Trial
- William M. Vollmer, PhD;
- Frank M. Sacks, MD; and
- Lawrence J. Appel, MD
- Center for Health Research; Kaiser Permanente NW; Portland, OR 97227 Brigham and Women's Hospital; Boston, MA 02115 Johns Hopkins University; Baltimore, MD 21205
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IN RESPONSE:
Drs. Jürgens and Graudal base their argument on the observation that, although reduced sodium significantly lowered systolic blood pressure in nonhypertensive white persons, it did not significantly lower diastolic blood pressure in this subgroup. First, the effect on diastolic blood pressure in this group was indeed significant (−1.4 mm Hg [95% CI, −2.8 mm Hg to −0.1 mm Hg] in those following the control diet). Second, we would like to clarify that our subgroup results for this trial have consistently reported data for African-American persons versus non–African-American persons; the latter group is composed predominantly of white persons. Finally, our Table 4 actually provides estimated effects for nonhypertensive non–African-American persons in each of four age–sex subgroups. All four estimated effects on systolic blood pressure were statistically significant, and three of four effects on diastolic blood pressure had P values less than 0.10. Given that the trial was not powered to look at many subgroups simultaneously, we find these results impressive.
Drs. Jürgens and Graudal cite a meta-analysis that does not support the blood pressure–lowering effects of sodium reduction in normotensive persons (1); however, another meta-analysis (2) reached the opposite conclusion. We would also point out that the DASH-Sodium Trial was a controlled feeding study and thus represents an efficacy trial. This distinguishes it from large lifestyle-intervention trials, such as the one cited by Drs. Jürgens and Graudal (3), which are better characterized as effectiveness trials. For a variety of reasons, including the limited availability of processed foods that are reduced in sodium, such trials would be expected to show smaller blood pressure effects than our trial. Drs. Jürgens and Graudal totally ignore the potential of reduced sodium intake for the primary prevention of hypertension. Blood pressure is related to cardiovascular risk throughout the range of blood pressure, including nonhypertensive levels. Even in those with optimal blood pressure who may not experience a blood pressure reduction, it is not unreasonable to expect that reduced sodium intake (as well as other nonpharmacologic strategies for controlling blood pressure) may blunt the known increase in systolic blood pressure that occurs with increasing age. We therefore stand by our original recommendation that the DASH diet and reduced sodium intake should be broadly recommended for the prevention and treatment of hypertension and its sequelae.
William M. Vollmer, PhD
Center for Health Research
Kaiser Permanente NW
Portland, OR 97227
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
Annals welcomes electronically submitted letters.
- Copyright ©2004 by the American College of Physicians
