Table 2.

Grade/Strength of Recommendation Classification Systems for Included Guidelines.^a

Guideline Developer	Grade/Strength of Recommendation System
NICE	Strength of recommendations Some recommendations can be made with more certainty than others. The Guideline Development Group makes a recommendation based on the trade-off between the benefits and harms of an intervention, taking into account the quality of the underpinning evidence. For some interventions, the Guideline Development Group is confident that, given the information it has looked at, most patients would choose the intervention. The wording used in the recommendations in this guideline denotes the certainty with which the recommendation is made (the strength of the recommendation). For all recommendations, NICE expects that there is discussion with the patient about the risks and benefits of the interventions and their values and preferences. This discussion aims to help them to reach a fully informed decision. Interventions that must (or must not) be used  We usually use ‘must’ or ‘must not’ only if there is a legal duty to apply the recommendation. Occasionally we use ‘must’ (or ‘must not’) if the consequences of not following the recommendation could be extremely serious or potentially life threatening. Interventions that should (or should not) be used—a ‘strong’ recommendation  We use ‘offer’ (and similar words such as ‘refer’ or ‘advise’) when we are confident that, for the vast majority of patients, an intervention will do more good than harm and be cost-effective. We use similar forms of words (for example, ‘Do not offer…’) when we are confident that an intervention will not be of benefit for most patients. Interventions that could be used  We use ‘consider’ when we are confident that an intervention will do more good than harm for most patients and be cost-effective, but other options may be similarly cost-effective. The choice of intervention, and whether or not to have the intervention at all, is more likely to depend on the patient’s values and preferences than for a strong recommendation, and so the health care professional should spend more time considering and discussing the options with the patient.
SIGN	Levels of Evidence 1++ High-quality meta-analyses, systematic reviews of RCTs, or RCTs with a very low risk of bias 1+ Well-conducted meta-analyses, systematic reviews, or RCTs with a low risk of bias 1– Meta-analyses, systematic reviews, or RCTs with a high risk of bias 2++ High-quality systematic reviews of case control or cohort studies, or high-quality case control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causal 2+ Well-conducted case control or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causal 2– Case control or cohort studies with a high risk of confounding or bias and a significant risk that the relationship is not causal 3 Nonanalytic studies (e.g., case reports, case series) 4 Expert opinion Grades of Recommendation A: At least 1 meta-analysis, systematic review, or RCT rated as 1++ and directly applicable to the target population, or a body of evidence consisting principally of studies rated as 1+, directly applicable to the target population and demonstrating overall consistency of results B: A body of evidence including studies rated as 2++, directly applicable to the target population and demonstrating overall consistency of results, or extrapolated evidence from studies rated as 1++ or 1+ C: A body of evidence including studies rated as 2+, directly applicable to the target population and demonstrating overall consistency of results, or extrapolated evidence from studies rated as 2++ D: Evidence level 3 or 4 or extrapolated evidence from studies rated as 2+ Good Practice Points: Recommended best practice based on the clinical experience of the guideline development group
European Psychiatric Association	Uses same system as SIGN (see row above)
American Psychiatric Association	Rating the Strength of Supporting Research Evidence In accordance with the Methods Guide of the Agency for Healthcare Research and Quality, the ratings are defined as follows: High (denoted by the letter A) = High confidence that the evidence reflects the true effect. Further research is very unlikely to change our confidence in the estimate of effect. Moderate (denoted by the letter B) = Moderate confidence that the evidence reflects the true effect. Further research may change our confidence in the estimate of effect and may change the estimate. Low (denoted by the letter C) = Low confidence that the evidence reflects the true effect. Further research is likely to change our confidence in the estimate of effect and is likely to change the estimate. Rating the Strength of Recommendations Each guideline statement is separately rated to indicate strength of recommendation and strength of supporting research evidence. “Strength of recommendation” describes the level of confidence that potential benefits of an intervention outweigh potential harms. This level of confidence is informed by available evidence, which includes evidence from clinical trials as well as expert opinion and patient values and preferences. As described under “Guideline Development Process,” the rating is a consensus judgment of the authors of the guideline and is endorsed by the APA Board of Trustees. There are two possible ratings: recommendation or suggestion. These correspond to ratings of “strong” or “weak” (also termed “conditional”) as defined under the GRADE method for rating recommendations in clinical practice guidelines. “Recommendation” indicates confidence that the benefits of the intervention clearly outweigh harms. “Suggestion” indicates uncertainty (i.e., the balance of benefits and harms is difficult to judge or either the benefits or the harms are unclear).

^aNICE, National Institute for Health and Care Excellence; RCT, randomised controlled trial; SIGN, Scottish Intercollegiate Guidelines Network.