Let us return to the scenario of the patient reluctant to have surgery to control his angina. Is it reasonable to use the composite end point from the TIME trial (death, myocardial infarction, and hospital admission for acute coronary syndrome) to guide the decision, or should we focus on individual results of the three components?
To determine the answer, we can ask the three questions in the box. In response to the first question, most patients will find death and serious myocardial infarction with subsequent disability far more important than a short admission for acute coronary syndrome with rapid return to previous function.
Composite end points are outcomes that capture the number of patients experiencing one or more of several adverse events
The validity of composite end points depends on similarity in patient importance, treatment effect, and number of events across the components
When large variations exist between components the composite end point should be abandoned
The answers to the other two questions are also negative. Hospital admissions occurred far more frequently than the two more important events (table). Biological rationale fails to support a presumption that the invasive strategy will have similar effects on all three end points. Indeed, the investigators explicitly state that they expect an increase in short term deaths with surgery, while achieving benefits in terms of decreased angina and associated hospital admissions. The trend toward increased deaths, with a large reduction in admissions, with the invasive strategy provides support for this hypothesis. The composite end point thus fails all three criteria and provides little useful information for clinical decision making.