The J-curve phenomenon and the treatment of hypertension: is there a point beyond which pressure reduction is dangerous?

Article Abstract:

Although there is substantial evidence that uncontrolled hypertension (high blood pressure) increases illness and deaths caused by cardiovascular disease, there is still a question about the extent to which blood pressure should be lowered. Some studies suggest that excessive reductions may lead to increased mortality, in effect, producing a ''J-curve'' whereby reduction to a certain level is beneficial, but after that point lacks further benefits, and may even cause harm. Others imply ''the lower the better.'' Unfortunately, the data in most studies supporting the latter view have been manipulated in a way that makes the detection of a J-curve impossible. Only a linear relationship can be detected, a severe limitation improperly based on an a priori assumption. In order to test for a J-shaped curve, a study of 48,000 subjects in 13 studies was undertaken. It was found that there was no consistent J-shaped curve between treated blood pressure level and stroke, but a consistent J-curve is apparent for cardiac events (e.g., heart attacks). This type of curve is most marked in subjects who already have heart disease. The J-curve effect may help explain why the major hypertension studies show little to no effects on deaths from heart attacks. This increased risk is probably not a result of drug therapy itself, but rather a result of the diastolic pressure being shifted from a safe level to a lower, unsafe level. Five hypotheses are outlined that could account for such a response. It is clear that lowering high blood pressure lowers the risk of stroke, but beyond a certain level such reductions may increase the risk of cardiac events. A reasonable approach would be caution about lowering diastolic blood pressure below 85 mm Hg in patients with known ischemic heart disease, especially since there is no evidence of any benefit for lowering blood pressure beyond this point. (Consumer Summary produced by Reliance Medical Information, Inc.)

Hypertension, Drug therapy

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Chronic Fatigue Syndrome -- Trials and Tribulations

Article Abstract:

A comprehensive review of all clinical trials covering treatments for chronic fatigue syndrome found that graded exercise therapy and cognitive-behavioral therapy were the most effective treatments. These results should not be rejected because doctors or patient advocates think the effectiveness of cognitive-behavior therapy proves or implies that the disease is psychosomatic.

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Interventions for the Treatment and Management of Chronic Fatigue Syndrome: A Systematic Review

Article Abstract:

Graded exercise therapy and cognitive behavioral therapy are the most effective treatments for chronic fatigue syndrome, according to researchers who analyzed 44 trials of various treatments covering 2,801 patients. There was insufficient evidence to recommend any other treatment, including many drugs, dietary supplements, and alternative/complementary medicines.

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