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. 2021 Jul 16;11(7):e051821. doi: 10.1136/bmjopen-2021-051821

Table 1.

Discrepancies in study characteristics (n=67 studies)

Characteristic No discrepancies Discrepancies
Characteristic reported in both preprint and journal publication Characteristic reported in neither preprint or journal publication Characteristic reported in preprint only Characteristic reported in journal publication only Characteristic reported in both preprint and journal publication, but with discrepancies in content
Examples of discrepancies*
Title 47 (70%) 0 (0%) 0 (0%) 0 (0%) 20 (30%)

  • Preprint includes study design in the title (n=4)

  • Journal publication includes study design in the title (n=5)

  • Change in study design description (n=5)

  • Change in population description (n=3)

  • Change in location description in both (n=3)
Authors 49 (73 %) 0 (0%) 0 (0%) 0 (0%) 18 (27%)

  • Additional author(s) in preprint (n=3)

  • Additional author(s) in journal publication (n=9)

  • Change in author order (n=6)

  • Change in spelling, wording, or order of author first/last names (n=2)
Disclosed funding source 44 (66%) 3 (4%) 8 (12%) 2 (3%) 10 (15%)

  • Additional funding sources in journal publication (n=4)

  • Funding statement in preprint provides more detail (n=1)

  • Funding statement in journal publication provides more detail (n=2)
Conflict of interest disclosure statement 50 (75%) 1 (1%) 5 (8%) 1 (1%) 10 (15%)

  • Additional conflicts reported in journal publication (n=8)

  • Additional conflicts reported in preprint (n=1)

  • Additional detail included in journal publication (n=2)
Ethics approval 59 (88%) 3 (5%) 1 (1%) 0 (0%) 4 (6%)

  • Preprint contains approval number but journal publication does not (N=1); preprint states approval was waived and journal publication states it was not needed (n=1); preprint contains no information on ethics approval, while journal publication describes the approvals (n=1); preprint states consent was approved prior to sample collection while article states it was approved from next of kin (n=1)
Location of study 63 (94%) 4 (6 %) 0 (0%) 0 (0%) 0 (0%)
Number of participants 61 (91%) 0 (0%) 0 (0%) 0 (0%) 6 (9%)

  • Journal publication has larger analytic sample size than preprint (n=2); Journal publication has smaller analytic sample size than preprint (n=1); different numbers of patients recruited, but same number randomizedrandomised; 284 patients recruited in preprint, 267 in journal publication (n=1); numbers do not match for any sampling or analysis (n=1); typographical error (n=1)
Participant demographics 38 (58%) 3 (4%) 0 (0%) 1 (1%) 25 (37%)

  • Journal publication includes additional demographic categories (n=10)

  • Preprint includes additional demographic categories (n=4)

  • Preprint and journal publication report different values for the same demographic characteristics (n=11)

  • Demographic data reported using different metrics (n=6)
Tables and Figures 18 (27%) 0 (0%) 0 (0%) 0 (0%) 49 (73%)

  • Journal publication includes additional tables/figures (n=25)

  • Preprint includes additional tables/figures (n=10) Additional data in journal publication tables (n=14) Additional data in preprint tables/figures (n=6)

  • Change in order of tables/figures (n=4)

  • Change in metrics (eg, mean vs median) (n=15)

  • Change in labels (n=5)

  • Numbers reported differed (n=16)
Discussion of limitations 27 (40%) 7 (11%) 0 (0%) 2 (3%) 31 (46%)

  • More limitations listed in journal publication than preprint (n=28)

  • More limitations listed in preprint than journal publication (n=1)

*Ns do not add to number of discrepancies between preprints and journal publications, as some studies could have more than one discrepancy and not all discrepancies have been included as examples.