The American journal of medicine
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The effects of diuretics on renal handling of potassium and magnesium can result in depletion of these electrolytes. Associations between these deficits and the occurrence of increased ventricular ectopy raise the issue of potential relationships to increased risk of sudden unexpected death in hypertensive patients taking diuretics, especially patients with electrocardiographic and electrolyte abnormalities. Review of diuretic effects on the kidneys provides evidence that diuretic regimens that conserve potassium also conserve magnesium, and suggests the important role of these agents in protecting against potassium and magnesium abnormalities.
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Diuretic-induced deficiencies in potassium and magnesium can have significant implications for patients with cardiovascular disease. Hypokalemia, found in up to 50 percent of patients receiving thiazide therapy, is associated with a greater frequency of serious arrhythmias and increased mortality in patients with acute myocardial infarction. ⋯ It has been shown that both potassium and magnesium are conserved by potassium-sparing agents. Because serum and tissue magnesium levels are not correlated and correlations for potassium levels are weak, prevention of these electrolyte abnormalities is advised.
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Randomized clinical trials have become the accepted scientific standard for evaluating therapeutic efficacy. Contradictory results from multiple randomized clinical trials on the same topic have been attributed either to methodologic deficiencies in the design of one of the trials or to small sample sizes that did not provide assurance that a meaningful therapeutic difference would be detected. When 36 topics with conflicting results that included over 200 randomized clinical trials in cardiology and gastroenterology were reviewed, it was discovered that results of randomized clinical trials often disagree because the complexity of the randomized clinical trial design and the clinical setting creates inconsistencies and variation in the therapeutic evaluation. ⋯ The design issues include eligibility criteria and the selection of study groups, baseline differences in the available population, variability in indications for the principal and concomitant therapies, protocol requirements of the randomized clinical trial, and management of intermediate outcomes. The issues in interpreting the trials include the regulatory effects of treatments, the frailty of double-blinding, and the occurrence of unexpected trial outcomes. The results of this review suggest that pooled analyses of conflicting results of randomized clinical trials (meta-analyses) may be misleading by obscuring important distinctions among trials, and that enhanced flexibility in strategies for data analysis will be needed to ensure the clinical applicability of randomized clinical trial results.