In the Journal Of The American Medical Association (JAMA) last month (sept9th 2009) a rather dull article was published that continues to raise significant questions about the availability of quality data required for optimal clarity in making clinical decisions.
For some time now it has been understood that trials can go missing, that is they are started but not reported on, mainly due to unwanted outcomes, rather than collapse of the trial. The result can be a level of selective publishing practice that highlights benefits rather than failure by excluding unsuccessful studies or may deliver a retrospectively applied outcome score to an allied interventional benefit when the proposed (wished for) outcome does not materialise.
Of the 323 included trials, 147 (45.5%) were adequately registered (ie, registered before the end of the trial, with the primary outcome clearly specified). Trial registration was lacking for 89 published reports (27.6%), 45 trials (13.9%) were registered after the completion of the study, 39 (12%) were registered with no or an unclear description of the primary outcome, and 3 (0.9%) were registered after the completion of the study and had an unclear description of the primary outcome. Among articles with trials adequately registered, 31% (46 of 147) showed some evidence of discrepancies between the outcomes registered and the outcomes published. The influence of these discrepancies could be assessed in only half of them and in these statistically significant results were favored in 82.6% (19 of 23).
Comparison of the primary outcomes of RCTs registered with their subsequent publication indicated that selective outcome reporting is prevalent
Sylvain Mathieu, Isabelle Boutron, David Moher, Douglas G. Altman, and Philippe Ravaud Comparison of Registered and Published Primary Outcomes in Randomized Controlled Trials JAMA, Sep 2009; 302: 977 – 984 View Abstract