Making health promotion and disease prevention a clinical activity based on medical science is one of the most important developments in general internal medicine in the past few years. The US Preventive Services Task Force, working with the Canadian Task Force on the Periodic Health Examination, has outlined criteria for determining the appropriateness of screening for medical conditions.1,2 These criteria include the effectiveness of subsequent treatment if a condition is found, the burden of suffering caused by the condition, and the quality of the screening test.
Preventive activities range from simple primary interventions (eg, onetime immunizations) to recurring secondary interventions (eg, breast cancer screening) to more complex interventions that require ongoing efforts by clinicians and patients (eg, smoking cessation). The scientific evidence needed to justify a clinical intervention varies with each type of prevention. Finally, research has begun to determine what physicians can do to promote health by helping