Search

Rationale, aims and objectives Open-label extension (OLE) studies following blinded randomized controlled trials (RCTs) of pharmaceuticals are increasingly being carried out but do not conform to regulatory standards and questions surround the validity of their evidence. OLE studies are usually discussed as a homogenous group, yet substantial differences in study design still meet the definition of an OLE. We describe published papers reporting OLE studies focussing on stated objectives, design, conduct and reporting. Method A search of Embase and Medline databases for 1996 to July 2008 revealed 268 papers reporting OLE studies that met our eligibility criteria. A random sample of 50 was selected for detailed review. Results Over 80% of the studies had efficacy stated as an objective. The most common methods of allocation at the start of the OLE were for all RCT participants to switch to one active treatment or for only participants on the new drug to continue, but in three studies all participants were re-randomized at the start of the OLE. Eligibility criteria and other selection factors resulted in on average of 74% of participants in the preceding RCT(s) enrolling in the OLE and only 57% completed it. Conclusions Published OLE studies do not form a homogenous group with respect to design or retention of participants, and thus the validity of evidence from an OLE should be judged on an individual basis. The term 'open label' suggests bias through lack of blinding, but slippage in relation to the sample randomized in the preceding RCT may be the more important threat to validity. [ABSTRACT FROM AUTHOR]

Rationale, aims and objectives Systematic reviews, meta-analyses and clinical guidelines (reviews) are intended to inform clinical practice, and in this sense can be thought of as scientific truthmakers. High-quality controlled trials should align to this truth, and method quality markers should predict truth status. We sought to determine in what way controlled trial quality relates to scientific truth, and to determine predictive utility of trial quality and bibliographic markers. Method A sample of reviews in rehabilitation medicine was examined. Two scientific truth dimensions were established based on review outcomes. Quality and bibliographic markers were extracted from associated trials for use in a regression analysis of their predictive utility for trial truth status. Probability analysis was undertaken to examine judgments of future trial truth status. Results Of the 93 trials included in contemporaneous reviews, overall, n = 45 (48%) were true. Randomization was found more in true trials than false trials in one truth dimension ( P = 0.03). Intention-to-treat analysis was close to significant in one truth dimension ( P = 0.058), being more commonly used in false trials. There were no other significant differences in quality or bibliographic variables between true and false trials. Regression analysis revealed no significant predictors of trial truth status. Probability analysis reported that the reasonable chance of future trials being true was between 2 and 5%, based on a uniform prior. Conclusions The findings are at odds with what is considered gold-standard research methods, but in line with previous reports. Further work should focus on scientific dynamics within healthcare research and evidence-based practice constructs. [ABSTRACT FROM AUTHOR]