Randomized trials published in higher vs. lower impact journals differ in design, conduct, and analysis.
OBJECTIVE
To compare methodological characteristics of randomized controlled trials (RCTs) published in higher vs. lower impact Core Clinical Journals.


METHODS
We searched MEDLINE for RCTs published in 2007 in Core Clinical Journals. We randomly sampled 1,140 study reports in a 1:1 ratio in higher (five general medicine journals with the highest total citations in 2007) and lower impact journals.


RESULTS
Four hundred sixty-nine RCTs proved eligible: 219 in higher and 250 in lower impact journals. RCTs in higher vs. lower impact journals had larger sample sizes (median, 285 vs. 39), were more likely to receive industry funding (53% vs. 28%), declare concealment of allocation (66% vs. 36%), declare blinding of health care providers (53% vs. 41%) and outcome adjudicators (72% vs. 54%), report a patient-important primary outcome (69% vs. 50%), report subgroup analyses (64% vs. 26%), prespecify subgroup hypotheses (42% vs. 20%), and report a test for interaction (54% vs. 27%); P < 0.05 for all differences.


CONCLUSIONS
RCTs published in higher impact journals were more likely to report methodological safeguards against bias and patient-important outcomes than those published in lower impact journals. However, sufficient limitations remain such that publication in a higher impact journal does not ensure low risk of bias.
2nd Department of Internal Medicine, Jagiellonian University School of Medicine, Skawinska 8, 31-066 Krakow, Poland.
Malgorzata M
MM
Bala
Elie A
EA
Akl
Xin
X
Sun
Dirk
D
Bassler
Dominik
D
Mertz
Filip
F
Mejza
Per Olav
PO
Vandvik
German
G
Malaga
Bradley C
BC
Johnston
Philipp
P
Dahm
Pablo
P
Alonso-Coello
Natalia
N
Diaz-Granados
Sadeesh K
SK
Srinathan
Basil
B
Hassouneh
Matthias
M
Briel
Jason W
JW
Busse
John J
JJ
You
Stephen D
SD
Walter
Douglas G
DG
Altman
Gordon H
GH
Guyatt
D015982:Bias; D003627:Data Interpretation, Statistical; D006801:Humans; D055811:Journal Impact Factor; D010506:Periodicals as Topic / Q000592:standards* / Q000706:statistics & numerical data; D016032:Randomized Controlled Trials as Topic / Q000379:methods / Q000592:standards*; D012107:Research Design / Q000592:standards; D018401:Sample Size