A Modified Approach to Grading of Evidence

H H ealth care organization, delivery, and outcomes of care are the basic requirements of and the focus of health care for research, practice, and policy (1,2). Since the inception of evidence-based medicine in 1992, the emphasis on evidence-based medicine, comparative effectiveness research, evidence synthesis and the development of guidelines continues to grow (1). The emphasis on evidence synthesis and development of guidelines has been the focus of the Institute of Medicine (IOM) leading to the re-engineering of its definition of clinical guidelines in 2011, along with the establishment of standards for systematic reviews Clinical practice guidelines are statements that include recommendations intended to optimize patient care that are formed by a systematic review of evidence (3). The IOM also described a systematic review as a scientific investigation that focuses on a specific question and uses explicit, pre-specified scientific methods to identify, select, assess, and summarize the findings of similar but separate studies. Meta-analysis, in contrast to a systematic review, is the statistical pooling of data across studies to generate a summaries or pooled estimate of effects (5). However, challenges in implementing the IOM's systematic review standards and deficiencies of IOM's standards in guideline development have ALSO been described. It has been shown that the IOM failed to follow its own standards (6) and that even the Agency for Healthcare Research and Quality (AHRQ) Evidence-based Practice Centers (EPCs) have found it difficult to implement the IOM systematic review standards (7). West et al (8), in the evidence report describing systems to rate the strength of scientific evidence, conceptualized that a continuum exists from rating the quality of the study to grading the strength of a body of evidence. Grading the strength of a body of evidence incorporates judgments of study quality, but it also includes how confident one is that a finding is true and whether others using different studies or different people have detected the same finding.