PubMed · 2378636
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M F Ryan, N Corbett, I Clark, M Peters. 1990-04-07. Pocket programmable computers in clinical practice.. https://doi.org/10.1136/bmj.300.6729.940-c
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Many studies have demonstrated a strong association between elevated plasma total homocyst(e)ine levels and vascular diseases. Consequently, hyperhomocyst(e)inemia is now generally accepted as an independent risk factor for coronary artery disease. We critically reviewed the results of 35 human studies in which the levels of plasma total homocysteine were measured in patients with atherosclerotic diseases (n = 4338) and in controls (n = 22,593). Total homocysteine levels were consistently higher in patients than in controls. The average of this increment among 23 case-control studies was 26%. New insights into the biochemical pathways of total homocysteine metabolism, the factors that influence total homocysteine levels, genetic contributions to hyperhomocyst(e)inemia, the pathogenesis of homocyst(e)ine-induced vascular damage, and current recommendations for treatment of hyperhomocyst(e)inemia were also reviewed. Various lines of evidence now link hyperhomocyst(e)inemia with vascular diseases. Although there are no data from double-blind, placebo-controlled clinical trials of treatment for hyperhomocyst(e)inemia, the strong epidemiologic and experimental evidence argues for treatment of hyperhomocyst(e)inemia; in fact, its treatment with low doses of vitamins is thought to be safe and is inexpensive.
The statement of hypotheses and choice of statistical tests in clinical trials that compare surgical with nonsurgical treatment are complicated by the likelihood of excess risk in the surgical group during the perioperative period but lower risk after that compared with the more uniform risk in the nonsurgical group. Commonly used statistical survival analyses implicitly assume a constant ratio of risks in the 2 groups during the follow-up period. However, the changing pattern of risk for one treatment but not the other implies that the assessment of the relative efficacy of the treatments varies with the length of the follow-up. As such, determining whether survival curves for the 2 groups are different may not translate easily into selecting the best treatment. Alternative statements of the hypothesis based on consideration of the time horizon of patients and on clinical judgment may be more consistent with the goals of the study. Regardless of the choice of a statistical test, the choice of treatment is a decision specific to the individual patient and should be influenced by the patient's life expectancy, attitude toward taking risks, quality of life, and cost considerations. When the survival curves cross, there is a trade-off between the risk of surgery and the increase in life expectancy among the survivors of surgery. Accordingly, assessment of differences in outcomes in clinical trials comparing surgical vs nonsurgical therapy should provide both a conclusion about whether 1 treatment can reasonably be considered best for most patients and should provide information to the individual patient and physician on the expected outcome to aid in the decision-making process.