Certainty of evidence assessment in high-impact medical journals: A meta-epidemiological survey

While certainty of evidence assessment is key to a rigorous and transparent systematic review, it is unknown how - and how frequently - it is assessed in systematic reviews. The objective of this study was to examine the prevalence and approaches used for certainty of evidence assessment in systematic reviews published in high-impact medicine journals over the past 11 years.

A PubMed search and hand-searching of relevant journal websites identified systematic reviews published between 24 January 2013 and 23 January 2024 in any of the ten highest-impact journals in the General and Internal Medicine category of the Journal Citation Report. Two reviewers independently selected any systematic review related to health outcomes assessing certainty of evidence using any method. We extracted data related to review characteristics, certainty of evidence and risk of bias/methodological quality assessment frameworks, and reported consideration of certainty of evidence domains. Logistic regression examined year of publication to determine whether the prevalence of certainty of evidence assessment changed over time.

Of 1,023 included reviews, 346 (33.8%) assessed certainty of evidence. Prevalence of certainty of evidence assessment increased over time (0.16 ± 0.2; p < .001). Most (89.3%) of reviews used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework to assess certainty of evidence.

Only one in three systematic reviews published in the highest-impact medical journals over the past 11 years assessed certainty of evidence, though prevalence increased over time. The use of specific domains within each certainty of evidence framework was not clearly described in all reviews.