A 59-year-old man comes to the office for follow-up. He has a history of hypertension for which he takes 2 antihypertensive agents. The patient has no other cardiovascular problems and does not smoke. On examination, his blood pressure is 145/90 mm Hg and BMI is 25.4 kg/m². The remainder of the examination is unremarkable. Laboratory studies show elevated fasting lipid levels, including LDL cholesterol. His 10-year risk of cardiovascular events is calculated as 10%, and a discussion regarding moderate or intensive statin therapy is initiated. The patient has read that statins may cause diabetes and asks if there is an even more increased risk with intensive compared to moderate statin therapy. Based on the abstract, what was the pooled odds ratio of major cardiovascular events among participants on intensive compared to moderate statin therapy?

Question

Quizplus · Accepted Answer

Explanation: The odds ratio (OR) is a measure of association between an exposure and an outcome. In this case, it represents the odds that an outcome (eg, major cardiovascular event) will occur in the presence of a particular exposure (eg, intensive statin therapy) compared to the odds of that outcome in a control group. An OR >1 means that the exposure is associated with higher odds of the outcome and an OR <1 means that the exposure is associated with lower odds of the outcome. This meta-analysis provides a pooled OR based on the results of the 5 trials. According to the abstract, and using the standard format for a 2 × 2 contingency table, 3134 (= a) out of 16408 (= a + b) subjects experienced major cardiovascular events in the intensive statin therapy group compared to 3550 (= c) out of 16344 (= c + d) in the moderate statin therapy group. A total of 6684 (= a + c) experienced major cardiovascular events. Based on these data, the following table can be completed, with b and d being determined by subtraction: standard format for a 2 × 2 contingency table The odds ratio (OR), pooled from all 5 studies, is given by: OR = ad/bc = (3134 × 12794) / (13274 × 3550) = 0.85, indicating a lower odds of major cardiovascular events with intensive compared to moderate statin therapy. (Choice E) The value 1.30 is obtained by multiplying the numbers in the table shown in the abstract: (18.9 × 51.6) / (16.9 × 44.5). This table is not in the correct format, as seen above. Educational objective: The odds ratio (OR) is a measure of association between an exposure and an outcome. It can be calculated based on a 2 × 2 contingency table, using the formula: OR = ad/bc.

A 59-Year-Old Man Comes to the Office for Follow-Up