Table of Contents

1 Abbreviations

BMJ = The BMJ
cat = categorical
chars = characters
CI = confidence interval
DOAJ = Directory of Open Access Journals
ext = extended
IQR = interquartile range
JAMA = Journal of the American Medical Association
New Engl J Med = New England Journal of Medicine OAD = open access designation
PLoS Med = PLoS Medicine
PMCID = PubMed Central identifier
RCT = randomized controlled trial
RE = random effect
SD = standard deviation
SE = standard error
WoS = Web of Science

2 Notes

Meta-analyses: The logit transformation was used for the meta-analysis of binary variables for estimating the pooled proportions, standard errors were not back transformed. For some variables, meta-analyses were performed with and without articles published in 2020 because the relevant information was completed in the Web of Science (WoS) data base after our data export date.

Regression models: For all regression models, the journal BMJ was used as reference category. Linear mixed models with journal as fixed effect and time as random effect were performed. Linear regression models with journal and time as fixed effects were used for sensitivity analyses.

Citation analyses: For citation analyses, only articles published between 2011 and 2018 were considered to analyze articles with a citation period of at least 2 years. The number of total citations were investigated using quasi Poisson regression models. Quantile regression on the log number of total citations shifted by 1 was used for sensitivity analyses.

3 Number of articles

The following table gives an overview of original research articles per year and per journal after the data management of the PubMed and WoS export data.

Number of original research articles
Characteristic BMJ, N = 1,3981 JAMA, N = 1,6271 Lancet, N = 1,6051 New Engl J Med, N = 2,1531 PLoS Med, N = 1,3131
Publication Year
2011 177 170 151 215 86
2012 204 180 151 222 79
2013 148 175 153 222 79
2014 133 173 141 210 80
2015 141 161 170 221 70
2016 103 149 191 204 138
2017 114 170 166 204 157
2018 129 147 161 207 158
2019 127 153 169 209 204
2020 122 149 152 239 262
Absolute frequency of research articles.

1 n

4 Descriptive statistics

4.1 Criteria

4.1.1 Continuous variables

Characteristic BMJ, N = 1,398 JAMA, N = 1,627 Lancet, N = 1,605 New Engl J Med, N = 2,153 PLoS Med, N = 1,313
Title length (chars)
Mean (SD) 130.3 (34.3) 126.6 (39.4) 154.6 (43.4) 69.4 (9.0) 140.2 (33.1)
Median (IQR) 127.0 (107.0, 151.0) 127.0 (96.0, 153.0) 153.0 (124.0, 183.0) 71.0 (65.0, 75.0) 138.0 (118.0, 161.0)
Range 46.0, 304.0 24.0, 279.0 38.0, 345.0 32.0, 119.0 58.0, 258.0
Title length (words)
Mean (SD) 17.9 (4.8) 17.6 (5.6) 21.6 (6.2) 9.7 (1.8) 20.1 (4.9)
Median (IQR) 18.0 (15.0, 21.0) 17.0 (13.0, 21.0) 21.0 (17.0, 25.0) 10.0 (8.0, 11.0) 20.0 (17.0, 23.0)
Range 6.0, 39.0 2.0, 40.0 4.0, 55.0 4.0, 17.0 8.0, 38.0
Length of article
Mean (SD) 10.5 (2.6) 9.7 (1.9) 11.0 (7.1) 10.7 (1.4) 17.8 (5.0)
Median (IQR) 10.0 (9.0, 12.0) 10.0 (8.2, 11.0) 10.0 (9.0, 11.0) 11.0 (10.0, 12.0) 18.0 (15.0, 20.0)
Range 5.0, 27.0 4.0, 29.0 5.0, 86.0 5.0, 18.0 6.0, 41.0
Unknown 176 9 23 44 17
Number of references
Mean (SD) 40.5 (14.6) 32.8 (8.9) 34.3 (14.0) 29.9 (8.7) 46.4 (20.2)
Median (IQR) 38.0 (30.0, 48.0) 33.0 (27.0, 38.0) 31.0 (28.0, 37.0) 30.0 (24.0, 37.0) 43.0 (34.0, 55.0)
Range 11.0, 130.0 7.0, 89.0 10.0, 192.0 5.0, 76.0 12.0, 341.0
Unknown 176 9 23 44 17
Number of authors
Mean (SD) 9.0 (7.2) 15.0 (12.5) 17.5 (14.1) 20.9 (13.7) 12.0 (10.7)
Median (IQR) 7.0 (5.0, 11.0) 12.0 (7.0, 19.0) 14.0 (9.0, 22.0) 18.0 (12.0, 26.0) 9.0 (6.0, 14.0)
Range 1.0, 101.0 1.0, 102.0 1.0, 101.0 1.0, 102.0 1.0, 101.0

4.1.2 Categorical variables

4.1.2.1 Articles published 2011-2020

Characteristic BMJ, N = 1,3981 JAMA, N = 1,6271 Lancet, N = 1,6051 New Engl J Med, N = 2,1531 PLoS Med, N = 1,3131
Less than 10 words (Albert)
0 1,370.0 (98.0%) 1,539.0 (94.6%) 1,587.0 (98.9%) 1,165.0 (54.1%) 1,311.0 (99.8%)
1 28.0 (2.0%) 88.0 (5.4%) 18.0 (1.1%) 988.0 (45.9%) 2.0 (0.2%)
At least 20 words (Albert)
0 910.0 (65.1%) 1,058.0 (65.0%) 629.0 (39.2%) 2,153.0 (100.0%) 639.0 (48.7%)
1 488.0 (34.9%) 569.0 (35.0%) 976.0 (60.8%) 0.0 (0.0%) 674.0 (51.3%)
Absolute verbs (Goodman)
0 1,391.0 (99.5%) 1,627.0 (100.0%) 1,590.0 (99.1%) 2,125.0 (98.7%) 1,302.0 (99.2%)
1 7.0 (0.5%) 0.0 (0.0%) 15.0 (0.9%) 28.0 (1.3%) 11.0 (0.8%)
Relative verbs (Goodman)
0 1,362.0 (97.4%) 1,623.0 (99.8%) 1,582.0 (98.6%) 2,146.0 (99.7%) 1,290.0 (98.2%)
1 36.0 (2.6%) 4.0 (0.2%) 23.0 (1.4%) 7.0 (0.3%) 23.0 (1.8%)
Nounal verbs (Goodman)
0 1,358.0 (97.1%) 1,608.0 (98.8%) 1,579.0 (98.4%) 2,146.0 (99.7%) 1,287.0 (98.0%)
1 40.0 (2.9%) 19.0 (1.2%) 26.0 (1.6%) 7.0 (0.3%) 26.0 (2.0%)
Active verbs (Goodman)
0 1,315.0 (94.1%) 1,604.0 (98.6%) 1,542.0 (96.1%) 2,111.0 (98.0%) 1,254.0 (95.5%)
1 83.0 (5.9%) 23.0 (1.4%) 63.0 (3.9%) 42.0 (2.0%) 59.0 (4.5%)
Corporate authors
0 1,251.0 (89.5%) 1,209.0 (74.3%) 995.0 (62.0%) 1,199.0 (55.7%) 1,170.0 (89.1%)
1 147.0 (10.5%) 418.0 (25.7%) 610.0 (38.0%) 954.0 (44.3%) 143.0 (10.9%)
RCT (title)
0 1,104.0 (79.0%) 939.0 (57.7%) 630.0 (39.3%) 2,038.0 (94.7%) 1,066.0 (81.2%)
1 294.0 (21.0%) 688.0 (42.3%) 975.0 (60.7%) 115.0 (5.3%) 247.0 (18.8%)
RCT (abstract)
0 848.0 (69.4%) 803.0 (49.6%) 543.0 (34.3%) 773.0 (36.7%) 867.0 (66.9%)
1 374.0 (30.6%) 815.0 (50.4%) 1,039.0 (65.7%) 1,336.0 (63.3%) 429.0 (33.1%)
Unknown 176 9 23 44 17
RCT (title or abstract)
0 1,001.0 (71.6%) 804.0 (49.4%) 544.0 (33.9%) 813.0 (37.8%) 879.0 (66.9%)
1 397.0 (28.4%) 823.0 (50.6%) 1,061.0 (66.1%) 1,340.0 (62.2%) 434.0 (33.1%)
Open access (PubMed)
0 76.0 (5.4%) 603.0 (37.1%) 1,047.0 (65.2%) 1,297.0 (60.2%) 6.0 (0.5%)
1 1,322.0 (94.6%) 1,024.0 (62.9%) 558.0 (34.8%) 856.0 (39.8%) 1,307.0 (99.5%)
Open access (WoS binary)
0 185.0 (13.2%) 112.0 (6.9%) 883.0 (55.0%) 520.0 (24.2%) 17.0 (1.3%)
1 1,213.0 (86.8%) 1,515.0 (93.1%) 722.0 (45.0%) 1,633.0 (75.8%) 1,296.0 (98.7%)
Open access (WoS & PubMed cat.)
Bronze or Green Published 192.0 (13.8%) 1,523.0 (96.8%) 218.0 (29.9%) 1,292.0 (77.7%) 12.0 (0.9%)
Gold 1,197.0 (86.2%) 4.0 (0.3%) 296.0 (40.6%) 1.0 (0.1%) 1,296.0 (99.1%)
Green Accepted 0.0 (0.0%) 47.0 (3.0%) 215.0 (29.5%) 369.0 (22.2%) 0.0 (0.0%)
Unknown 9 53 876 491 5
Open access (WoS & PubMed cat. ext.)
Bronze or Green Published 192.0 (13.8%) 1,523.0 (96.8%) 218.0 (29.9%) 1,292.0 (77.7%) 12.0 (0.9%)
DOAJ Gold 0.0 (0.0%) 0.0 (0.0%) 0.0 (0.0%) 0.0 (0.0%) 1,296.0 (99.1%)
Green Accepted 0.0 (0.0%) 47.0 (3.0%) 215.0 (29.5%) 369.0 (22.2%) 0.0 (0.0%)
Other Gold 1,197.0 (86.2%) 4.0 (0.3%) 296.0 (40.6%) 1.0 (0.1%) 0.0 (0.0%)
Unknown 9 53 876 491 5
Open access (PubMed & WoS)
0 9.0 (0.6%) 53.0 (3.3%) 876.0 (54.6%) 491.0 (22.8%) 5.0 (0.4%)
1 1,389.0 (99.4%) 1,574.0 (96.7%) 729.0 (45.4%) 1,662.0 (77.2%) 1,308.0 (99.6%)
Country
0 1,226.0 (87.7%) 1,571.0 (96.6%) 1,418.0 (88.3%) 2,093.0 (97.2%) 914.0 (69.6%)
1 172.0 (12.3%) 56.0 (3.4%) 187.0 (11.7%) 60.0 (2.8%) 399.0 (30.4%)
City
0 1,369.0 (97.9%) 1,611.0 (99.0%) 1,582.0 (98.6%) 2,142.0 (99.5%) 1,258.0 (95.8%)
1 29.0 (2.1%) 16.0 (1.0%) 23.0 (1.4%) 11.0 (0.5%) 55.0 (4.2%)
Geography
0 1,207.0 (86.3%) 1,563.0 (96.1%) 1,410.0 (87.9%) 2,087.0 (96.9%) 894.0 (68.1%)
1 191.0 (13.7%) 64.0 (3.9%) 195.0 (12.1%) 66.0 (3.1%) 419.0 (31.9%)
Colon
0 14.0 (1.0%) 923.0 (56.7%) 25.0 (1.6%) 2,153.0 (100.0%) 37.0 (2.8%)
1 1,384.0 (99.0%) 704.0 (43.3%) 1,580.0 (98.4%) 0.0 (0.0%) 1,276.0 (97.2%)

1 n (%)

4.1.2.2 Articles published 2011-2019

Characteristic BMJ, N = 1,2761 JAMA, N = 1,4781 Lancet, N = 1,4531 New Engl J Med, N = 1,9141 PLoS Med, N = 1,0511
Corporate authors
0 1,141.0 (89.4%) 1,104.0 (74.7%) 883.0 (60.8%) 1,047.0 (54.7%) 930.0 (88.5%)
1 135.0 (10.6%) 374.0 (25.3%) 570.0 (39.2%) 867.0 (45.3%) 121.0 (11.5%)
Open access (PMCID)
0 73.0 (5.7%) 597.0 (40.4%) 968.0 (66.6%) 1,142.0 (59.7%) 0.0 (0.0%)
1 1,203.0 (94.3%) 881.0 (59.6%) 485.0 (33.4%) 772.0 (40.3%) 1,051.0 (100.0%)
Open access (WoS binary)
0 169.0 (13.2%) 52.0 (3.5%) 813.0 (56.0%) 377.0 (19.7%) 7.0 (0.7%)
1 1,107.0 (86.8%) 1,426.0 (96.5%) 640.0 (44.0%) 1,537.0 (80.3%) 1,044.0 (99.3%)
Open access (WoS & PubMed cat.)
Bronze or Green Published 176.0 (13.9%) 1,380.0 (96.5%) 177.0 (27.6%) 1,178.0 (76.6%) 7.0 (0.7%)
Gold 1,092.0 (86.1%) 4.0 (0.3%) 254.0 (39.6%) 1.0 (0.1%) 1,044.0 (99.3%)
Green Accepted 0.0 (0.0%) 46.0 (3.2%) 211.0 (32.9%) 358.0 (23.3%) 0.0 (0.0%)
Unknown 8 48 811 377 0
Open access (WoS & PubMed cat. ext.)
Bronze or Green Published 176.0 (13.9%) 1,380.0 (96.5%) 177.0 (27.6%) 1,178.0 (76.6%) 7.0 (0.7%)
DOAJ Gold 0.0 (0.0%) 0.0 (0.0%) 0.0 (0.0%) 0.0 (0.0%) 1,044.0 (99.3%)
Green Accepted 0.0 (0.0%) 46.0 (3.2%) 211.0 (32.9%) 358.0 (23.3%) 0.0 (0.0%)
Other Gold 1,092.0 (86.1%) 4.0 (0.3%) 254.0 (39.6%) 1.0 (0.1%) 0.0 (0.0%)
Unknown 8 48 811 377 0
Open access (PubMed & WoS)
0 8.0 (0.6%) 48.0 (3.2%) 811.0 (55.8%) 377.0 (19.7%) 0.0 (0.0%)
1 1,268.0 (99.4%) 1,430.0 (96.8%) 642.0 (44.2%) 1,537.0 (80.3%) 1,051.0 (100.0%)

1 n (%)

4.2 Citations

Mean (SD) of cumulative citation frequency per journal for articles published between 2011 and 2018
BMJ JAMA Lancet New Engl J Med PLoS Med
2011 3.39 (4.34) 6.16 (11.19) 10.42 (13.39) 14.62 (19.55) 2.81 (4.15)
2012 8.41 (12.13) 17.57 (27.26) 27.35 (37.83) 47.85 (74.73) 7.87 (10.43)
2013 14.50 (19.14) 32.36 (56.41) 52.07 (70.08) 86.95 (134.55) 13.53 (16.85)
2014 22.03 (27.09) 48.76 (87.93) 80.17 (126.02) 129.09 (196.60) 19.16 (22.43)
2015 28.67 (35.06) 66.10 (119.79) 104.15 (189.01) 171.25 (255.42) 25.78 (30.30)
2016 36.18 (42.43) 83.78 (155.04) 125.68 (246.00) 216.91 (315.17) 28.33 (38.92)
2017 42.57 (49.61) 99.22 (183.26) 150.61 (300.87) 259.11 (379.61) 30.75 (47.01)
2018 47.92 (56.34) 116.05 (207.53) 176.62 (348.09) 298.61 (439.59) 33.98 (54.73)
2019 59.90 (63.38) 146.90 (236.57) 228.60 (418.82) 378.74 (518.58) 45.18 (65.89)
2020 71.14 (70.71) 175.98 (263.50) 278.69 (485.70) 454.96 (601.07) 56.01 (76.66)

Distribution of citation frequency over the years

Raw distribution:

Log transformed distribution:

5 Meta-analyses

5.1 Title length

5.1.1 Characters

Random effect meta-analysis per journal - title length in characters
Estimate SE Lower 95% CI Upper 95% CI
BMJ 130.11 10.65 109.24 150.99
JAMA 125.02 11.56 102.37 147.68
Lancet 153.93 13.35 127.77 180.09
New Engl J Med 69.48 2.78 64.02 74.93
PLoS Med 136.29 9.70 117.29 155.30