Clinicians have always intuitively understood the value of disease control and prevention. Early intervention in the course of a disease or even before disease develops has saved the lives of millions of people. Although immunization and screening tests remain important for controlling and preventing diseases, the most promising role for disease control may lie in educating people and changing the personal health behaviors before clinical disease develops.

Screening tests such as the Pap smear (for cervical cancer), mammography (for breast cancer), and the Prostate Specific Antigen (PSA) level (for prostate cancer) have all been successful in dramatically reducing the incidence of many cancers. Routine physical examinations and screening for hypertension and other risk factors for heart disease have significantly brought down the mortality from stroke and heart attacks. Similarly, because of very rigid rules for childhood immunizations, once-common childhood infections (e.g. diphtheria, pertussis, measles) have...