Guidelines are popular these days. They are mentioned in journal articles,1-3 editorials,4 insurance company contracts, and federal legislation. The Institute of Medicine has dedicated two reports to the subject.5,6
Unfortunately, the word guideline covers a broad spectrum of intellectual products. Some are hard to follow. They use weasel words instead of numeric thresholds or explicit criteria at their decision points and do not really tell you what to do. We say these are not decidable. Drug package inserts are notorious: "Serum electrolytes (particularly potassium), CO2, creatinine and BUN should be determined frequently during the first few months of Lasix therapy and periodically thereafter."7 Guidelines for isoniazid prophylaxis, in contrast, are explicit and easy to follow.8
Some are simple, describing the indications for a single action and requiring access to only a few variables for their execution. The Centers for Disease Control and Prevention guidelines