controlled trial; II-1 = Evidence obtained from well-designed controlled trials without randomization. II-2 = Evidence obtained from well-designed cohort or case-control analytic studies, perferably from more than one center or research group; II-3 = Evidence obtained from multiple time series with or without the intervention, dramatic results in uncontrolled experiments (such as the results of the introduction of penicillin treatment in the 1940s) could also be regarded as this type of evidence. III = Opinions of respected authorities, based on clinical experience; descriptive studies and case reports; or reports of expert committees.

b Strength of Recommendations: A = There is good evidence to support the recommendation that the condition be specifically considered in a periodic health examination; B = There is fair evidence to support the recommendation that the condition be specifically considered in a periodic health examination; C = There is insufficient evidence to recommend for or against the inclusion of the condition in a periodic health examination, but recommendations may be made on other grounds; D = There is fair evidence to support the recommendation that the condition be excluded from consideration in a periodic health examination; E = There is good evidence to support the recommendation that the condition be excluded from consideration in a periodic health examination.

c These trials generally involved specially trained educators such as dietitians delivering intensive interventions (e.g., multiple sessions, tailored materials) to selected patients with known risk factors.

SOURCE: USPSTF (U.S. Preventive Services Task Force). 1995. Guide to Clinical Preventive Services, 2nd ed. Report of the U.S. Preventive Services Task Force. Washington, D.C.: U.S. Department of Health and Human Services, Office of Public Health, Office of Health Promotion and Disease Prevention.



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