A set of interventions by clinicians, specific to a patient's age and sex, is generally believed to be effective in preventing disease. Clinical preventive interventions include efforts to prevent diseases from arising (primary prevention), as with immunizations or counseling on smoking cessation, and efforts to detect diseases earlier in their course when they can be treated more effectively (secondary prevention), as with mammography, cervical Papanicolaou smears, or stool testing for occult blood. Information supporting the effectiveness of clinical preventive interventions done as part of periodic health examinations is summarized in recommendations by several expert groups that have been published in