Evolution of clinical practice guidelines: evidence supporting expanded use of medicines.

Previous studies have shown that the primary factor underlying increased spending on pharmaceuticals has been the rising utilization of medications, rather than increases in unit drug price. This study examined the evolution of clinical practice guidelines to assess possible reasons for the rising drug volume. Clinical practice guidelines from 1970 to the present were reviewed for the six most prevalent treatable medical conditions/risk factors listed as priority areas by the Institute of Medicine. We searched the National Guidelines Clearinghouse, PubMed and Medline databases, and Web sites of relevant national organizations for US clinical practice guidelines published through January 2005. Information pertaining to the therapeutic regimen (eg, the frequency and duration of recommended treatment, when treatment should be initiated, the patient population for whom the guideline was intended) was abstracted and entered into evidence tables. Changes in guidelines were distributed across three themes that recommended evidence-based increases in medication use, including: (1) changes in the size of the treatable population; (2) changes in the number and type of recommended pharmaceutical therapeutic options, including movement from monotherapy to combination therapy, treatment of comorbidities, and use of newer types of medicines; and (3) changes in the therapeutic regimen, including a shift from episodic care to preventive and chronic care. Many of these changes point to an important, but not often noticed, addition of secondary prevention of disease effects to the objectives of medical care. These trends are likely to continue with important economic, clinical, and policy ramifications.