Research
Prominent medical journals often provide insufficient information to assess the validity of studies with negative results
-
* Corresponding author: Randy S Hebert hebertrs@msx.upmc.edu
1 Division of General Internal Medicine, University of Pittsburgh, 933W MUH, 200 Lothrop Street, Pittsburgh, PA 15213, USA
2 Division of General Internal Medicine, Johns Hopkins Bayview Medical Center, Johns Hopkins University School of Medicine, A6W, 4940 Eastern AvenueBaltimore, MD 21224, USA
3 Division of General Internal Medicine, Vanderbilt University Medical Center, S-1121 MCN 2587, Nashville, TN 37232, USA
Journal of Negative Results in BioMedicine 2002, 1:1 doi:10.1186/1477-5751-1-1
Published: 30 September 2002Abstract
Background
Physicians reading the medical literature attempt to determine whether research studies are valid. However, articles with negative results may not provide sufficient information to allow physicians to properly assess validity.
Methods
We analyzed all original research articles with negative results published in 1997 in the weekly journals BMJ, JAMA, Lancet, and New England Journal of Medicine as well as those published in the 1997 and 1998 issues of the bimonthly Annals of Internal Medicine (N = 234). Our primary objective was to quantify the proportion of studies with negative results that comment on power and present confidence intervals. Secondary outcomes were to quantify the proportion of these studies with a specified effect size and a defined primary outcome. Stratified analyses by study design were also performed.
Results
Only 30% of the articles with negative results comment on power. The reporting of power (range: 15%-52%) and confidence intervals (range: 55–81%) varied significantly among journals. Observational studies of etiology/risk factors addressed power less frequently (15%, 95% CI, 8–21%) than did clinical trials (56%, 95% CI, 46–67%, p < 0.001). While 87% of articles with power calculations specified an effect size the authors sought to detect, a minority gave a rationale for the effect size. Only half of the studies with negative results clearly defined a primary outcome.
Conclusion
Prominent medical journals often provide insufficient information to assess the validity of studies with negative results.