Be careful with composites
Kevin Lomangino's article discusses the limitations of composite outcomes and surrogate markers.Key Concepts addressed:
It”s increasingly clear that surrogate endpoints don”t tell the entire story when it comes to a treatment”s effectiveness. Just a couple of weeks ago, we learned that a drug which raises “good” cholesterol (a surrogate for cardiovascular disease risk) had no effect on the incidence of heart attacks and strokes. Previous research found that aggressively lowering blood sugar (a surrogate for diabetes complications) actually increased the risk of death among individuals with type 2 diabetes.
Such findings remind us to focus more closely on the real outcomes that matter to patients –- things like death, disease severity, time spent in the hospital, and patient quality of life. But even these supposedly “real” outcomes can give us an inflated sense of how well a treatment works if we don”t evaluate the results carefully. This is especially true for studies that employ so-called composite endpoints, or outcomes that consist of two or more components that are combined into a single result.