Showing posts with label epidemiology. Show all posts
Showing posts with label epidemiology. Show all posts

Tuesday, March 10, 2020

Research Shorts: U.S. Guideline Developers Inconsistently Applying Criteria for Appropriate Evidence Grading

Contributed by Philipp Dahm, MD, MHSc, FACS

Guideline Developers in the United States were Inconsistent in Applying Criteria for Appropriate GRADE Use


Our study was motivated by the anecdotal observation that many US-based organizations appeared to be endorsing the GRADE approach but did not necessarily apply it to the fullest extent. We therefore sought to formally study this issue applying six published criteria of appropriate GRADE use. We limited to search to guidelines from US-based organizations that were included in the National Guideline Clearinghouse (NGC) which implied that they met certain, minimal criteria for evidence-based guidelines. Our search reached back to January 2011 and went to June 2018 after which time the NGCH lost its funding and stopped existing in that form.

Among guidelines documents from 315 organizations included in the database, 135 were from the US and were represented by at least one guideline. Our analysis ultimately included 67 guideline documents from 44 organizations. The vast majority of these guidelines were from professional organizations; mostly related to the field of internal medicine and its subspecialties. With regard to domains for rating the certainty of evidence, only one in 10 was explicit about including all five criteria for downgrading (study limitations, indirectness, inconsistency, imprecision, and publication bias) for a body of evidence from randomized trials and all three domains (large magnitude of effect, dose-response gradient, and direction of residual bias) for rating up a body of evidence from non-randomized trials. Over half of guidelines described explicit consideration of all four central domains (certainty of evidence, balance of benefits to harms, patients’ values and preferences and resource utilization) for moving from evidence to recommendations. All guidelines included the certainty of evidence and the vast majority also addressed the balance of desirable and undesirable consequences. When comparing guidelines published in 2011-2014 versus 2015-18, rates of appropriate use were higher for nearly all criteria, but only one main criterion met statistical significance, namely the reporting of evidence summaries supporting recommendations.

The take-home messages from this study are that one-in-three US based organizations developing evidence-based guidelines report the use of GRADE but that adherence to published criteria is quite inconsistent. As GRADE finds increasing uptake worldwide, continued efforts in training guideline methodologists and panel members will be important to assure appropriate application of GRADE methodology.


Dixon C, Dixon PE, Sultan S, Mustafa R, Morgan RL, Murad MH, Falck-Ytter Y, Dahm P. Guideline Developers in the United States were Inconsistent in Applying Criteria for Appropriate GRADE Use. Journal of Clinical Epidemiology. 2020 Mar 4.

Wednesday, February 19, 2020

Research Shorts: Informative statements to communicate the findings of reviews

Contributed by Madelin Siedler, 2019/2020 U.S. GRADE Network Research Fellow

When authors of systematic reviews utilize the GRADE approach to evaluate the certainty of evidence in their findings, they should present this information in a way that is clear, consistent, and useful to the reader. In a recent article from the GRADE series (GRADE guidelines 26) in the Journal of Clinical Epidemiology, Santesso and colleagues present recommendations for communicating the effect size and certainty of evidence within a systematic review. These statements were informed by years of research, feedback, and discussion, including the qualitative input of around 100 methodology experts and a survey of 110 respondents of diverse backgrounds and levels of GRADE expertise.

The final result was a table of suggested statements organized by the certainty of the effect followed by the size of that effect based on the point estimate. In order to use this tool, systematic review authors will need to first determine thresholds for the size of the effect (i.e., whether the effect on an outcome is trivial, small, moderate, or large, or if there is no effect). This can be accomplished in “full contextualization,” in which the outcome is considered in relation to all other critical outcomes, or “partial contextualization,” in relation to the standalone value of the single outcome.

The suggested statements generated from the table can be used throughout the text of a systematic review, from the abstract to the discussion, and as part of any review type, such as those examining the accuracy of test strategies. The included language is also simple enough to be included as part of a plain language summary or other consumer-facing materials.


Santesso N, Glenton C, Dahm P, Garner P, Akl E, Alper B, Brignardello-Petersen R, Carrasco-Labra A, De Beer H, Hultcrantz M, Kuijpers T Meerpohl J, Morgan R, Mustafa R, Skoetz N, Sultan S, Wiysonge C, Guyatt G, Schünemann HJ. GRADE guidelines 26: Informative statements to communicate the findings of systematic reviews of interventions. Journal of clinical epidemiology. 2019 Nov 9.

Manuscript available here on publisher's site.

Monday, February 3, 2020

Research Shorts: From test accuracy to patient-important outcomes and recommendations

Contributed by Madelin Siedler, 2019/2020 U.S. GRADE Network Research Fellow

The potential risks and benefits of a screening or diagnostic testing strategy extend beyond the immediate impact and accuracy of the test itself. The result of testing will determine the available next steps and options for follow-up and management, and therefore will affect various patient-important outcomes in addition to potential resource utilization and equity considerations. These downstream consequences, and the certainty of evidence in these consequences, need to be considered when formulating recommendations surrounding testing. In a July 2019 paper published as part 22 of the Journal of Clinical Epidemiology’s GRADE guidelines series, Schünemann and colleagues provide suggestions for assessing certainty of evidence and determining recommendations for diagnostic tests and strategies.

While a collection of randomized controlled trial evidence examining the downstream consequences of various testing strategies is ideal in this scenario, such data are sparse. In lieu of this, guideline authors should develop a framework that includes each possible testing and follow-up treatment scenario, starting with the test in question and ending with patient-important outcomes.


 H.J. Schunemann et al. / Journal of Clinical Epidemiology 111 (2019) 69e82

As seen in this USPSTF sample framework, evidence begins with accuracy studies and ends with patient-important end-points.

This will allow the panel to visually link all relevant existing data together and develop clinical questions that are answerable with the evidence at hand. Data on the accuracy of a given test will help inform the expected number of false negatives and positives, which would then lead to potentially important downstream consequences - such as anxiety or a missed diagnosis - in addition to the effects of treating a diagnosed condition. The estimates of these beneficial and harmful potential outcomes should ideally come from a systematic review of evidence which can then be assessed for certainty. 

H.J. Schunemann et al. / Journal of Clinical Epidemiology 111 (2019) 69e82

The authors suggest providing one overall rating of the quality of evidence that takes into account the certainty of the diagnostic, prognostic, and management data that are available. Guideline panels should determine which outcomes of these bodies of evidence are critical and ascribe an overall rating based on the lowest level of certainty of the critical outcomes. 


Schünemann HJ, Mustafa RA, Brozek J, Santesso N, Bossuyt PM, Steingart KR, Leeflang M, Lange S, Trenti T, Langendam M, Scholten R. GRADE guidelines: 22. The GRADE approach for tests and strategies—from test accuracy to patient-important outcomes and recommendations. Journal of clinical epidemiology. 2019 Jul 1;111:69-82.

Manuscript available here on publisher's site.

Wednesday, January 22, 2020

Research Shorts: Rating the certainty in evidence in the absence of a single estimate of effect

Contributed by Madelin Siedler, 2019/2020 U.S. GRADE Network Research Fellow

When a pooled estimate from a meta-analysis of several studies is not present to guide the rating of evidence in these domains, how should one make a final determination of the certainty of evidence using GRADE? 


Evidence from a 30,000-foot view

In their 2017 paper published in Evidence-Based Medicine, Murad and colleagues describe methods for applying GRADE when bodies of evidence are either sparse or too disparate to pool. A systematic review, for instance, may only provide a narrative synthesis of the current evidence given these limitations. When a neat estimate of effect presented as part of a tidy forest plot is not available, it is necessary to use one’s best judgment to rate the domains by taking a broader view. In these cases, Murad et al. recommend the following approach:
  • Risk of Bias: Judge the risk of bias across all studies that include the outcome of interest.
  • Inconsistency: Consider the direction and size of the estimates of effect from each study. Generally, do they all tell the same story, or do they vary considerably?
  • Indirectness: Make an overall judgment about the amount of directness or indirectness of the body of evidence, given your specific question (always consider your population, intervention, outcome, and comparator[s] of interest). Generally, are the studies synthesized answering questions similar to yours? Or might the dissimilarities be enough to lower your trust in the estimate of effect as it pertains to your question?
  • Imprecision: Examine the total information size of all studies (number of events for binary outcomes, or number of participants for continuous outcomes) as well as each study’s reported confidence interval for this outcome. If there are fewer than 400 total events or participants, or if the confidence intervals from most studies - or the largest - include no effect, imprecision is likely present.
  • Publication bias: Suspect publication bias if there is a small number of only positive studies, or if data were reported in trial registries but never published.
As always, one may consider rating up the quality of evidence from an observational study if a large magnitude of effect, a dose-response gradient, or plausible residual confounding that would increase the certainty of effect are present in the majority of studies examined.


Murad MH, Mustafa RA, Schünemann HJ, Sultan S, Santesso N. Rating the certainty in evidence in the absence of a single estimate of effect. BMJ Evidence-Based Medicine. 2017 Jun 1;22(3):85-7.

Manuscript available here on publisher's site.