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Table 2 Change in evidence components, between and within evidence sources, in the overall sample and in a subgroup of randomized controlled trials and observational studies usable for quantitative evidence synthesisa

From: Changes in evidence for studies assessing interventions for COVID-19 reported in preprints: meta-research study

  Overall sample (n = 139)b COVID-NMA subgroup (n = 25)a
Change between or within at least one evidence source pair (n = 139) First to latest preprint version (n = 91) First preprint version to journal article (n = 66) Latest preprint version to journal article (n = 18) Change between or within at least one evidence source pair (n = 25) First to latest preprint version (n = 18) First preprint version to journal article (n = 15) Latest preprint version to journal article (n = 7)
Change in at least 1 evidence component 63 (45) 35 (38) 36 (55) 8 (44) 15 (60) 8 (44) 12 (86) 3 (43)
Change in study results 42 (30) 23 (25) 25 (38) 6 (33) 10 (40) 5 (28) 9 (64) 3 (43)
Change in risk of bias assessment 5 (20) 1 (6) 4 (27) 1 (14)
Change in abstract conclusion 33 (24) 18 (20) 19 (29) 3 (17) 8 (32) 5 (28) 5 (36) 1 (14)
  1. aIncludes studies used in quantitative evidence synthesis and GRADE development in the COVID-NMA project (randomized controlled trials; interrupted time-series, non-randomized studies using causal inference analysis or multivariable regression adjustment, including at least 150 incident users), with multiple evidence sources or evidence source versions. For more information see: https://covid-nma.com/emulated/
  2. bIncludes the studies in the COVID-NMA subgroup