Assessing the clinical effectiveness of preventive maneuvers: analytic principles and systematic methods in reviewing evidence and developing clinical practice recommendations. A report by the Canadian Task Force on the Periodic Health Examination. This paper examines a process for evaluating clinical effectiveness and developing recommendations in which systematic methods are used to review evidence from published clinical research and to reach sound conclusions about appropriate medical policy. The methodology addresses four important components of the analytic process: (1) the criteria that must be satisfied for a clinical practice to be considered effective; (2) proper methods for reviewing evidence from published clinical research to determine whether a clinical practice meets these criteria (including methods for performing comprehensive literature reviews, for judging the quality of individual studies, and for synthesizing or pooling the results of multiple studies); (3) theoretical and practical concerns in translating the results of the scientific review into sound clinical practice recommendations; and (4) the importance of documentation, guidelines, and other safeguards to minimize the effect the reviewers themselves have on the objectivity and consistency of the analytic methods. 