When is evidence sufficient ahrq

They are not designated by Roman numerals or other symbols. Assigning a grade of high, moderate, or low implies that an evidence base is available from which to estimate an effect.

EPCs understand that, even when evidence is low, consumers, clinicians, and policymakers may find themselves in the position of having to make choices and decisions.

The designations of high, moderate, and low should convey how secure reviewers feel about decisions based on evidence of differing grades. In some cases, the reviewers cannot draw conclusions for a particular outcome, specific comparison, or other question of interest. In these situations, the EPC should assign a grade of insufficient. Such situations arise in two main ways. First, evidence for an outcome receives a grade of insufficient when no evidence is available from the included studies.

This case includes the absence of any relevant studies whatsoever. In CERs, for example, certain drug comparisons may never have been studied or published in head-to-head trials and placebo-controlled trials of the multiple drugs of interest may not provide adequate indirect evidence for any comparisons.

Second, a grade of insufficient is also appropriate when evidence on the outcome is too weak, sparse, or inconsistent to permit any conclusion to be drawn. This situation can reflect several complicated conditions, such as unacceptably high risk of bias or a major inconsistency that cannot be explained e.

Imprecise data may also lead to a grade of insufficient, specifically when the confidence interval is so wide that it includes two incompatible conclusions: that one treatment is clinically significantly better than the other and that it is worse. Indirect data based on only one study or comparison could also receive a grade of insufficient. If a single quantitative estimate is desired, the strength of evidence may be insufficient if an effect size cannot be calculated from reported information or if heterogeneity cannot be explained.

To assign an overall grade to the strength of a body of evidence, EPCs must decide how to incorporate multiple domains into that overall assessment. In some systems, such as that of the GRADE working group, the overall grade for strength of evidence which it calls quality of evidence is calculated from the ratings for each domain using a method that provides guidance on how to upgrade or downgrade the rating of the evidence.

Such a system has the advantage of transparency because it clearly delineates a direct path from the evidence to its grade. Although a system that uses such a method may offer advantages in terms of transparency, as yet there is not empirical evidence to support the superiority of a particular point system compared with a more qualitative approach. Furthermore, some evidence suggests no difference in accuracy between quantitative and qualitative systems. Thus, EPCs may use different approaches to incorporate multiple domains into an overall strength-of-evidence grade.

The EPCs should explain the rationale for their approach to rating of strength of evidence and note which domains were important in upgrading or downgrading the strength of evidence. GRADE uses an algorithm to help reviewers to be clear about how they consider domains to produce the grade.

EPCs may use the GRADE system or their own weighting system, or they may elect to use a qualitative approach, so long as the rationale for ratings of strength of evidence is clear. Several general principles that all should follow are important. First, the risk of bias based on the design and conduct of the available studies is an essential component to rating the overall body of evidence.

In considering the risk-of-bias domain, EPCs should consider which study design is most appropriate to reduce bias for each question. For many of the traditional therapeutic interventions, evidence that is based on well-conducted randomized trials will have less risk of bias than does evidence based on observational studies.

For these outcomes, if randomized trial data are available, EPCs may choose to start with a rating of low for the risk-of-bias domain and change the assessment of this domain if the RCTs have important flaws.

For these traditional therapeutic intervention questions, observational data would generally start with a high risk of bias but may be altered depending on the conduct of the study. As with all questions, the overall strength of evidence must incorporate assessments of other domains in addition to risk of bias. Second, EPCs should assess each of the major domains for rating the overall strength of evidence.

Assessment of consistency, directness, and precision may reveal strengths or weaknesses with the entire body of evidence and lead to a strength of evidence that is either higher or lower than would be obtained by considering only risk of bias. EPCs should also consider the additional domains when appropriate; they need not report on those domains when they regard them as irrelevant to the review in question. The strength of the evidence would be weakened by concerns about publication bias.

In contrast, several factors may increase strength of evidence and are especially relevant for observational studies, where one may typically begin with a lower overall strength of evidence based on the risk of bias. Presence of a clear dose-response association or a very strong association would justify increasing strength of evidence.

If the confounding that may exist in a study would decrease the observed effect, but an effect is observed despite this possible confounding, the EPC may wish to upgrade the strength of evidence. Third, EPCs should decide a priori how to incorporate each domain into an overall strength of evidence and what measures they will use to ensure accuracy and consistency of evidence ratings.

The degree to which the overall strength of evidence is altered by additional domains that are used is a judgment that EPCs should explain in the report. EPCs should also take specific steps to ensure reliability and transparency within their own work both in individual reviews and across them when incorporating domains into an overall grade.

As a first step, they should be explicit about whether the evidence grade will be determined by a point system for combining ratings of the domains or by a qualitative consideration of the domains.

They should carefully document procedures used to grade strength of evidence and provide enough detail within the report to assure that the users can grasp the methods that were employed. EPCs should, furthermore, keep records of their procedures and results for each review so that they may contribute to the overall EPC expertise and science of grading evidence. Second, EPCs should identify the domains that are most important for the targeted body of evidence and decide how to weight the domains when assigning the evidence grade.

For the sake of consistency across reviews, the domains should be defined using the terminology presented in this chapter. In the absence of evidence to support specific systems for weighting of the domains, both qualitative and quantitative approaches are acceptable. In general, the first or highest priority should be given to the domain for risk of bias, as it is well established that evidence is strongest when the study design and conduct have the lowest risk of bias.

The third step is to develop an explicit procedure for ensuring a high degree of inter-rater reliability for rating individual domains. As mentioned earlier, this assumes that at least two reviewers with appropriate clinical and methodological expertise will rate each domain.

In addition, EPCs should assess the resulting inter-rater reliability for each domain. Although EPCs generally will not include the details of the reliability assessment in their CERs, they should keep records of this information. By documenting this information, EPCs will be able to increase knowledge about the reliability of the grading system. The fourth step is to use the ratings of the domains to assign an overall strength-of-evidence grade according to the decisions made in the first through third steps.

If this action involves a qualitative approach with subjective weighting of the domains, EPCs should consider using at least two reviewers and assessing the inter-rater reliability of this step in the process. That will not be necessary if the approach involves a formulaic calculation or algorithm based on the ratings of the domains. However, the scoring system or algorithm should be specified in sufficient detail to permit readers to replicate it if desired.

The fifth step is to prepare a narrative explanation of the reasoning used to arrive at the overall grade for each body of evidence. This should include an explanation of what domains played important roles in the ultimate grades. As noted above, CERs should present information about all comparisons of interest for the outcomes that are most important to patients and other decisionmakers. Thus, strength of evidence should relate to those important outcomes. Complete and perfect information is rarely available.

For some treatments, data may be lacking about one or more of the outcomes. In other cases, the available evidence comes from studies that have important flaws, is imprecise, or is not applicable to some populations of interest. For these reasons, EPCs should also present information that will help decisionmakers judge the risk of bias in the estimates of effect, assess the applicability of the evidence to populations of interest, and take imprecision and other factors into account.

Table 4 illustrates one approach to providing actionable information to decisionmakers that reflects strength of evidence.

It presents information pertinent to assessing evidence strength from different types of studies—specifically on the four required domains—and it displays estimates of the magnitude of effect right column. For the outcome as a whole e. It shows, for instance, that one fair-quality RCT reported mortality, which was lower by one patient per treated i. Had these estimates been precise and consistent e.

However, the evidence is insufficient to allow a conclusion for mortality. Although Table 4 illustrates how EPCs might organize information about the strength of evidence and magnitude of effect in ways useful to decisionmakers, it is incomplete.

First, the table does not convey any information about the applicability of the evidence, which would be presented through other means text or table. Second, a narrative summary of the results is also essential for interpreting the results of a literature synthesis.

The EPC program produces systematic reviews, but it is not involved directly in development of recommendations or guidelines. Rather, EPC reports are used by a spectrum of government agencies, professional societies, and other stakeholders. Our approach for grading strength of evidence and discussing applicability of the evidence is meant to facilitate use of the EPC reports by this broad group of users. We recommend that EPCs rate strength of evidence based on a core group of domains that include risk of bias, consistency, directness, and precision.

Randomized trials will generally be assessed to have a low risk of bias, which correlates with a high strength of evidence, but may be changed after evaluation of other domains. Evidence based on observational studies will generally have a high risk of bias, which correlates with a low strength of evidence, but may be rated higher after evaluating other domains. When appropriate, the EPCs can also use additional domains of dose-response association, the impact of plausible confounding, strength of association, and publication bias to upgrade or downgrade the strength of evidence.

In GRADE, evidence based on observational studies starts with a strength of low and can be upgraded based on several factors. In the approach we describe here, the EPC may believe that, for certain outcomes, such as harms, observational studies have less risk of bias than do randomized trials or that the available randomized trials have a substantial risk of bias.

In such instances, the EPC may either move up the initial rating of strength of evidence based on observational studies to moderate or move down the initial rating based on randomized trials to moderate or low. We recognize that some types of evidence, such as evidence about public health interventions, quality improvement studies, and studies of diagnostic tests, may be challenging to rate.

With these nontherapeutic intervention questions, the challenge to the EPCs is to determine the study design that is most appropriate to minimize the risk of bias. For example, the EPCs may find that particular types of studies, such as interrupted time series, reduce the risk of bias more than do other types of observational studies.

Although the EPCs can take into account criteria other than those specified expressly by GRADE in assessing the risk of bias of observational nonrandomized studies as moderate, we caution that changing the assessment of observational studies for risk of bias should be done judiciously.

AHRQ CERs have often focused on pharmaceutical therapies, for which both efficacy and effectiveness trials 15 are a major source of information. The domains discussed above are directly relevant to studies of most drugs. In the future, CERs may increasingly assess diagnostic tests or strategies. For these technologies, RCTs may not be the origin of much relevant information, and the studies that are available may have special methodologic features.

Further conceptual or empirical work may be warranted to explore whether the EPC approach to grading strength of evidence described here remains appropriate for such interventions. EPCs are encouraged to keep careful records of the application of these methods to nonpharmacologic interventions.

In arriving at an overall strength-of-evidence grade, the crucial requirement is transparency. The EPC method implies that EPCs can, if they choose, make a global assessment of the overall quality of evidence rather than explicitly use scores for each domain and then combine them. Being explicit and transparent about what criteria are used to raise or lower grades is the essential element in this step.

As noted earlier, the EPC approach emphasizes assessment of applicability separately from strength of evidence. GRADE also addresses applicability, which is incorporated within the general concept of directness. The rationale for the EPC approach is that many stakeholders use EPC reviews for developing guidelines or making clinical or health policy decisions, and they may have quite different views on how much, or little, the evidence applies to populations of interest to them.

Future EPC reports will have a discussion and information about applicability, and the intention is for the various users and audiences to read this section of the report and make their own judgments. A consistent approach for grading the strength of evidence—one that decisionmakers can readily recognize and interpret—is highly desirable.

Meanwhile, this paper codifies the interim guidance that EPCs can follow to strengthen the consistency within the AHRQ program's current and coming reports and products. The authors thank Valerie King, M. Using evidence reports: progress and challenges in evidence-based decision making. Health Aff Millwood ;24 1 Better information for better health care: the Evidence-based Practice Center program and the Agency for Healthcare Research and Quality.

Ann Intern Med Jun 21; 12 Pt 2 J Clin Epidemiol ; in press. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ Apr 26; What is "quality of evidence" and why is it important to clinicians? BMJ May 3; Systems to Rate the Strength of Scientific Evidence. A system for rating the stability and strength of medical evidence. Discrepancies among megatrials.

J Clin Epidemiol Dec;53 12 Fundamental deficiencies in the megatrial methodology. Curr Control Trials Cardiovasc Med ;2 1 Nutritional interventions for preventing and treating pressure ulcers.

The agency found limited information about whether telehealth affects health care cost and utilization. The authors of Telehealth: Mapping the Evidence for Patient Outcomes From Systematic Reviews identified 1, citations about telehealth in the current literature.

Then, they created an evidence map of 58 systematic reviews that assess the impact of telehealth on clinical outcomes. An evidence map is an abbreviated review designed to describe, rather than synthesize, available research. The AHRQ report takes a close look at the use of telehealth by older people with chronic diseases. These individuals, says the report, are likely to require frequent doctor visits for monitoring and management, as well as ongoing support to help them self-manage their conditions.

Registries can also be used as a source for research data. The NIH-funded American Gastroenterological Association AGA Fecal Microbiota Transplantation National Registry is an example of a research registry that collects data on outcomes and adverse events associated with fecal transplants to fill gaps in existing research. When designing the protocol for this registry, the researchers used the AHRQ handbook to inform the design.

Given that this is a research registry, it can be used by researchers to examine trends and outcomes of fecal transplant to treat Clostridium difficile colitis. Publications that use the registry as its source of data may be used in future systematic reviews, thus completing the cycle of learning.

The EPC program recognizes that gaps remain in the evidence to practice translation process and that more support is needed. The AHRQ EPC program supports initiatives to make evidence more actionable and provide resources and tools throughout all the phases of the learning healthcare system cycle.

This case study on C. Umscheid reports grants from AHRQ, during the conduct of the study; serves on the Advisory Board of DynaMed, and founded and directed a hospital-based evidence-based practice center. All other authors have nothing to disclose. The findings and conclusions in this document are those of the author s , who are responsible for its content, and do not necessarily represent the views of AHRQ. Department of Health and Human Services. Skip to main content. Choosing Wisely: Next Steps.

Published online first February 20, Hospital Medicine. Related Articles from PubMed End-of-life decisions in Greek intensive care units: a multicenter cohort study.

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