Cholesterol Lowering Guidelines: From Whence We Came and Where We Are Now.

Treatment guidelines have proliferated in cardiology, although most guideline recommendations are not supported by clinical trial evidence. What is considered to be a normal cholesterol level has progressively declined over the past 50 years, with the increasing realization that "normal" is far from optimal and that lower is better. The first important United States and Canadian cholesterol guidelines were published in 1988, and recommended diet for 6 months to be followed by consideration of bile acid sequestrants or nicotinic acid. Over the ensuing 25 years guidelines have changed rapidly and dramatically in response to a large number of definitive clinical trials, usually with statins. Low-density lipoprotein cholesterol targets have moved progressively lower, and in some guidelines, have been abandoned entirely. The concept of selecting patients for treatment according to the absolute risk reduction expected from treatment on the basis of clinical trial data seems to be a rational approach. For secondary prevention, some patients are still untreated or undertreated, presenting an opportunity for improving outcomes