| Evidence-Based Medicine Case 1 | ||||||||||||||||||||||||
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| A. The effectiveness of drug treatment for lipid disorders in patients with no history of coronary heart disease has been controversial. Pignone et al (2000) conducted a meta-analysis to summarise the effect of primary prevention with lipid lowering drugs on coronary heart disease events. They searched for randomised trials that examined drug treatment for patients with no known coronary heart disease, cerebrovascular disease, or peripheral vascular disease. Four studies met their eligibility criteria and were included in the analysis. See this paper as: Pignone et al, BMJ 2000, 321:1–5 B. The following table summarises some of the results:
Fill in the fourth column with the corresponding odds ratios (Hint: draw the 2x2 table for each study using the numbers provided and calculate odds ratios using the formula ad/bc). What these odds ratios show about the treatment? Does treatment with lipid lowering drugs reduce risk of coronary heart disease? Answer this question after consulting the forest plot of the odds ratios (figure). Would you recommend to your patients this treatment without reservations? C. How many people should be treated with these drugs in order to prevent one additional coronary heart event (number needed to treat, NNT)? (Hint: NNT=100/absolute risk difference).
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