Previous studies indicate that the interpretation of trial results can be distorted
by authors of published reports.
To identify the nature and frequency of distorted presentation or "spin" (ie, specific
reporting strategies, whatever their motive, to highlight that the experimental treatment
is beneficial, despite a statistically nonsignificant difference for the primary outcome,
or to distract the reader from statistically nonsignificant results) in published
reports of randomized controlled trials (RCTs) with statistically nonsignificant results
for primary outcomes.
March 2007 search of MEDLINE via PubMed using the Cochrane Highly Sensitive Search
Strategy to identify reports of RCTs published in December 2006.
Articles were included if they were parallel-group RCTs with a clearly identified
primary outcome showing statistically nonsignificant results (ie, P > or = .05).
Two readers appraised each selected article using a pretested, standardized data abstraction
form developed in a pilot test.
From the 616 published reports of RCTs examined, 72 were eligible and appraised. The
title was reported with spin in 13 articles (18.0%; 95% confidence interval [CI],
10.0%-28.9%). Spin was identified in the Results and Conclusions sections of the abstracts
of 27 (37.5%; 95% CI, 26.4%-49.7%) and 42 (58.3%; 95% CI, 46.1%-69.8%) reports, respectively,
with the conclusions of 17 (23.6%; 95% CI, 14.4%-35.1%) focusing only on treatment
effectiveness. Spin was identified in the main-text Results, Discussion, and Conclusions
sections of 21 (29.2%; 95% CI, 19.0%-41.1%), 31 (43.1%; 95% CI, 31.4%-55.3%), and
36 (50.0%; 95% CI, 38.0%-62.0%) reports, respectively. More than 40% of the reports
had spin in at least 2 of these sections in the main text.
In this representative sample of RCTs published in 2006 with statistically nonsignificant
primary outcomes, the reporting and interpretation of findings was frequently inconsistent
with the results.