Thursday, March 26, 2020

Extremely Serious Research Short: GRADE’s terminology for rating down by three levels

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

Since the inception of GRADE two decades ago, GRADE methodology has needed to evolve along with the arrival of new ways of assessing the evidence. One such evolution has come with the introduction of methods for assessing risk of bias for non-randomized studies, such as the Risk Of Bias In Non-randomized Studies (ROBINS-I) and the RoB Instrument for Nonrandomized Studies of Exposures (ROBINS-E).

Because these tools assess the risk of bias in non-randomized studies as if they represent a pragmatic trial, they automatically begin from a lower risk of bias than alternative assessments such as the Newcastle-Ottowa Scale. When rating down in GRADE, however, non-randomized studies start as low certainty of evidence before any rating up or down occurs. This means that while a study assessed with ROBINS-I or E would start as high-quality evidence, it may require a reduction of three levels if very serious risk of bias is present. In other words, a reduction of three levels for a study assessed with ROBINS-I or E would be analogous to a two-level reduction for a non-randomized study assessed with another method.

A rating by any other name…

In order to determine what exactly this new three-level reduction should be called, members of the GRADE Working Group conducted a survey of 225 participants recruited via social media, the Guidelines International Network (G-I-N), and other sources. Just over one-third (34.2%) were members of the GRADE Working Group and all respondents had participated in guideline development in some capacity. The results are presented in a newly published article as part of a new “GRADE Notes” series in the Journal of Clinical Epidemiology.

Within the survey, participants were asked to rate the following terms for this novel three-level reduction, from least (1) to most-favored (4):

  • Critically serious
  • Extremely serious
  • Most serious
  • Very, very serious

Respondents' average ranking of terms. 
T. Piggott et al. / Journal of Clinical Epidemiology - (2020)

“Extremely serious” took the lead as the most favorably ranked term with an average score of 3.19, with “critically serious” a close second at 3.12. Respondents found “extremely serious” the most agreeable due to its clarity and the fact that it seemed to “naturally” follow the existing two-level term, “very serious.”

The term “extremely serious” can now be found within the GRADEpro application when rating the certainty of evidence within non-randomized studies while utilizing the ROBINS-I or ROBINS-E instruments.



Piggott T, Morgan RL, Cuello-Garcia CA, Santesso N, Mustafa RA, Meerpohl JJ, Schünemann HJ, GRADE Working Group. GRADE notes: Extremely Serious, GRADE’s Terminology for Rating Down by 3-Levels. Journal of Clinical Epidemiology. 2019 Dec 19.

Manuscript available here on publisher's site.