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
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.
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
|
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 |
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 (%)
|
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 (%)
|
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:
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 |