Worldwide trends in volume and quality of published protocols of randomized controlled trials

Abstract

Background: Publishing protocols of randomized controlled trials (RCT) facilitates a detailed description of study rationale, design, and related ethical and safety issues. Little is known about how the practice of publishing protocols developed over time. Therefore, this study describes the worldwide trends in volume and methodological quality of RCT protocols. Methods: PubMed and EMBASE were searched, identifying 596 protocols published over a decade. Data were extracted on quality characteristics. Methodological quality was stated as high if adequate generation of allocation, concealment of allocation and intention-to-treat analysis were used. A comparison was made by publication period, geographical region and medical specialty. Results: The number of published RCT protocols increased from 69 in the first, to 390 in the third period (p<0.0001). Internal medicine and paediatrics were the most common topics. Whereas most protocols in the first period originated from North America (n=30, 44%), in the second and third this was Europe (respectively, n=65, 47% and n=190, 48%) (p=0.02). Quality of protocols was higher in Europe compared to North America. Surgical protocols had the highest quality among the three specialty topics used in this study (OR=1.94, CI=1.09-3.45, p=0.02). Conclusion: A five-fold increase in RCT protocol publication was observed. Although quality of protocols improved, it varied between geographical regions and across medical specialties. Improving training in RCT methodology is therefore important.