Dataset Information

High quality (certainty) evidence changes less often than low-quality evidence, but the magnitude of effect size does not systematically differ between studies with low versus high-quality evidence.

ABSTRACT:

Rationale, aims, and objectives

It is generally believed that evidence from low quality of evidence generate inaccurate estimates about treatment effects more often than evidence from high (certainty) quality evidence (CoE). As a result, we would expect that (a) estimates of effects of health interventions initially based on high CoE change less frequently than the effects estimated by lower CoE (b) the estimates of magnitude of effect size differ between high and low CoE. Empirical assessment of these foundational principles of evidence-based medicine has been lacking.

Methods

We reviewed the Cochrane Database of Systematic Reviews from January 2016 through May 2021 for pairs of original and updated reviews for change in CoE assessments based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) method. We assessed the difference in effect sizes between the original versus updated reviews as a function of change in CoE, which we report as a ratio of odds ratio (ROR). We compared ROR generated in the studies in which CoE changed from very low/low (VL/L) to moderate/high (M/H) versus M/H to VL/L. Heterogeneity and inconsistency were assessed using the tau and I² statistic. We also assessed the change in precision of effect estimates (by calculating the ratio of standard errors) (seR), and the absolute deviation in estimates of treatment effects (aROR).

Results

Four hundred and nineteen pairs of reviews were included of which 414 (207 × 2) informed the CoE appraisal and 384 (192 × 2) the assessment of effect size. We found that CoE originally appraised as VL/L had 2.1 [95% confidence interval (CI): 1.19-4.12; p = 0.0091] times higher odds to be changed in the future studies than M/H CoE. However, the effect size was not different (p = 1) when CoE changed from VL/L → M/H [ROR = 1.02 (95% CI: 0.74-1.39)] compared with M/H → VL/L (ROR = 1.02 [95% CI: 0.44-2.37]). Similar overlap in aROR between the VL/L → M/H versus M/H → VL/L subgroups was observed [median (IQR): 1.12 (1.07-1.57) vs. 1.21 (1.12-2.43)]. We observed large inconsistency across ROR estimates (I² = 99%). There was larger imprecision in treatment effects when CoE changed from VL/L → M/H (seR = 1.46) than when it changed from M/H → VL/L (seR = 0.72).

Conclusions

We found that low-quality evidence changes more often than high CoE. However, the effect size did not systematically differ between the studies with low versus high CoE. The finding that the effect size did not differ between low and high CoE indicate urgent need to refine current EBM critical appraisal methods.

SUBMITTER: Djulbegovic B

PROVIDER: S-EPMC9305903 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Clinical guidelines should be based on a thorough evaluation of the evidence and generally include a rating of the quality of evidence and assign a strength to recommendations. Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidance warns against making strong recommendations when the certainty of the evidence is low or very low, but has identified five paradigmatic situations (e.g. life-threatening situations) where this may be justified. We aimed to characterize the strength of recommendations and certainty of the evidence in Irish National Clinical Guidelines using the GRADE approach. All National Clinical Guidelines from the National Clinical Effectiveness Committee (NCEC) website using the GRADE approach (fully or partially) were included. All recommendations and their corresponding certainty of the evidence, strength of recommendations and justifications were extracted. Authors classified instances of strong recommendations with low certainty evidence (referred to as discordant recommendations) into one of the five paradigmatic situations. Descriptive statistics were calculated. From the 29 NCEC Clinical Guidelines available at the time of analysis, we identified 8 guidelines using GRADE with a total of 240 recommendations; 38 recommendations did not use the GRADE approach and were excluded. Half of the included guidelines focused on emergency situations. In the final dataset of 202 recommendations, 151 (74.7%) were classified as strong and 51 (25.3%) as conditional. Of the 151 strong recommendations, 55 (36.4%) were supported by high or moderate certainty evidence and 96 (63.6%) by low or very low certainty evidence and were considered discordant. Of these 96 discordant recommendations, 55 (73.7%) were consistent with one of the five paradigmatic situations. However, none were specifically described as such within the guidelines. The proportion of discordant recommendations identified in this analysis was higher than some previous international studies (range of all strong recommendations being discordant 30-50%), but similar to other guidelines focused on emergency situations. The majority of discordant recommendations could be mapped to one of the five situations, but no National Clinical Guideline explicitly referenced this. Guideline developers require further guidance to enable greater transparency in the reporting of the reasons for discordant recommendations.