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Dietary Calcium and Blood Pressure
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 Unpublished letters cannot be returned.
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TO THE EDITOR:
The simultaneous publication of two well-done meta-analyses of the effect of calcium supplementation on blood pressure [1, 2] gives insight into how meta-analyses are done. Both meta-analyses seem to have used rigorous methods, yet the number of studies combined (16 compared with 6 for hypertensive patients and 13 compared with 33 for normotensive patients) and the total number of study patients (1231 compared with 2412) were quite different. A brief review of some of the references indicates that the same study [3] was used for normotensive persons in one meta-analysis and for hypertensive patients in another and that different sample sizes were noted for the same [4]. The latter was also used for hypertensive patients in one meta-analysis and for normotensive persons in the other. Although the two meta-analyses have generally similar conclusions about the summary effect on blood pressure, the reported effect on diastolic blood pressure in hypertensive patients was statistically significant in one meta-analysis but not in the other. Fortunately for the reader, it seems that the overall effects are small enough to be dismissed as not useful in everyday clinical practice.
Daniel J. Cher, MD
Palo Alto Veterans Affairs Health Care System; Palo Alto, CA 94304
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
