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1.f. The Formulation of the Evidence into the Guidelines

In order to consider the evidence for each of the 23 questions, the panel met in groups of 6 to 10 members. During the first round of considering the evidence, 12 small groups of panel members were randomly assigned to consider the evidence for 2 or 3 questions. They developed evidence statements and determined the strength of the evidence using the criteria noted in Table A-I.  Their recommendations were presented to the full panel, which then made additional recommendations regarding their conclusions.

After considering additional studies for questions where adequate RCTs were not available, another iteration of evidence statements and recommendations was developed. The full panel met again to consider this iteration, which was considered by small groups assigned to focus on either a specific treatment modality or outcome measure. The small groups brought their recommendations back to the full panel for their final consideration. The panel weighed the evidence based on a thorough examination of the threshold or magnitude of the treatment effect.


Each evidence statement (other than those with no available evidence) and each recommendation is categorized by a level of certainty (A through D) as described in Table A-I below. The consensus process used for drawing conclusions and writing the recommendations was a group process that took into account all opinions.  Conclusions reflect the widest possible agreement of the panel.

Table A-1: Evidence Categories

Evidence Category Sources of Evidence Definition
Randomized controlled trials (rich body of data) Evidence is from endpoints of well-designed RCTs (or trials that depart only minimally from randomization) that provide a consistent pattern of findings in the population for which the recommendation is made. Category A therefore requires substantial numbers of studies involving substantial numbers of participants.
Randomized controlled trials (limited body of data) Evidence is from endpoints of intervention studies that include only a limited number of RCTs, post hoc or subgroup analysis of RCTs, or meta-analysis of RCTs. In general, Category B pertains when few randomized trials exist, they are small in size, and the trial results are somewhat inconsistent, or the trials were undertaken in a population that differs from the target population of the recommendation.
Nonrandomized trials  Observational studies Evidence is from outcomes of uncontrolled or nonrandomized trials or from observational studies.
Panel Consensus Judgment Expert judgment is based on the panel's synthesis of evidence from experimental research described in the literature and/or derived from the consensus of panel members based on clinical experience or knowledge that does not meet the above-listed criteria. This category is used only in cases where the provision of some guidance was deemed valuable but an adequately compelling clinical literature addressing the subject of the recommendation was deemed insufficient to justify placement in one of the other categories (A through C).
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