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Updated: Dec 12, 2025

Author Spotlight: Evaluating the Adjuvant Efficacy and Safety of Angong Niuhuang Pill in Viral Encephalitis Treatment
Published on: April 19, 2024
Abbreviated and comprehensive literature searches led to identical or very similar effect estimates: a
Hannah Ewald1, Irma Klerings2, Gernot Wagner2
1Department of Clinical Research, Basel Institute for Clinical Epidemiology and Biostatistics, University Hospital Basel, University of Basel, Basel, Switzerland; Swiss Tropical and Public Health Institute, Basel, Switzerland; University Medical Library, University of Basel, Basel, Switzerland.
Objectives:
The objective of this study was to assess the agreement of treatment effect estimates from meta-analyses based on abbreviated or comprehensive literature searches.
Study Design And Setting:
This was a meta-epidemiological study. We abbreviated 47 comprehensive Cochrane review searches and searched MEDLINE/Embase/CENTRAL alone, in combination, with/without checking references (658 new searches). We compared one meta-analysis from each review with recalculated ones based on abbreviated searches.
Results:
The 47 original meta-analyses included 444 trials (median 6 per review [interquartile range (IQR) 3-11]) with 360045 participants (median 1,371 per review [IQR 685-8,041]). Depending on the search approach, abbreviated searches led to identical effect estimates in 34-79% of meta-analyses, to different effect estimates with the same direction and level of statistical significance in 15-51%, and to opposite effects (or effects could not be estimated anymore) in 6-13%. The deviation of effect sizes was zero in 50% of the meta-analyses and in 75% not larger than 1.07-fold. Effect estimates of abbreviated searches were not consistently smaller or larger (median ratio of odds ratio 1 [IQR 1-1.01]) but more imprecise (1.02-1.06-fold larger standard errors).
Conclusion:
Abbreviated literature searches often led to identical or very similar effect estimates as comprehensive searches with slightly increased confidence intervals. Relevant deviations may occur.
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