Letters Section Editor: Robert M. Golub, MD, Senior Editor.
In Reply: Dr Punnam raises a question of whether different treatments for hypertension, hyperlipidemia, and diabetes received by participants in the Women’s Health Study may have confounded the findings. Participants in the Women’s Health Study were treated for these conditions by their personal physicians, not by the physicians in the Women’s Health Study. Thus it is possible that the treatments received may have differed among participants. However, the women were randomly assigned to the vitamin E and placebo groups. While randomization does not ensure the equal distribution of unmeasured confounders, with a study population of the size of the Women’s Health Study it is likely. As evidence of the success of the randomization procedure, the percentage of women with hypertension was similar in the 2 groups (25.6% in the vitamin E group vs 26.2% in the placebo group; P = .20), as was the percentage who had hyperlipidemia (29.3% vs 29.6%; P = .50) or diabetes (2.6% vs 2.6%; P = .83).
Lee I, Buring JE. Role of Vitamin E in the Prevention of Cardiovascular Disease and Cancer—Reply. JAMA. 2005;294(19):2432. doi:10.1001/jama.294.19.2432-b