How can we explain the duration of clinical trials?
A recent Nature Drug Discovery article written by L. Pregelj & her colleagues from the University of Queensland (Australia) found a solution with a multiple-regression model partially explaining the variation in clinical trial length. The controlling factors included trial primary purpose, end point classification, trial size, therapeutic class, geographic location, type of sponsoring organization.
Sample characteristics: trials started between 2005 and 2009, registered at ClinicalTrial.gov by February 2013. Total number of trials analyzed: 14’319 (Phase I, II or III)
A first view on the trials shows that:
– the numbers of individual trials registered each year rose;
– the length of these trials initially decreased across all phases.
But more details are needed to have better view of the real factors impacting the duration of clinical trials.
The authors built a model to assess whether the changes in clinical trial length depend on trial design specificities (primary purpose, phase, size, allocation,…), therapeutic class (anti-infectives, cancer drugs, cardiovascular medicines, CNS products, metabolics,…), geographic location, type of sponsoring organization (Government vs. Industry) or a combination of some of these factors
– overall mean length (unweighted): 21.6 months.
– 2 key factors influencing clinical trial length: type of sponsoring organization and therapeutic class. The trend for length is flat for the pharma industry meaning greater experience and knowledge enabled the companies to build efficiencies but further improvements will be difficult to achieve with standard trial design. The trend is decreasing for US Federal sponsored trials suggesting that best practices began to diffuse beyond the industry itself.
– despite the fact that the stage of the trial (Phase I, II or III) was not one of the two major factors contribution to the length of a clinical trial, the influence of this factor increased significantly in the recent years.
These results are surprising somehow as you would anticipate to have the stage of the trial as a major contributor to its length but the therapeutic class and the sponsor are far more important.
Nature Drug Discovery Article (Subscription required)
Understanding Clinical Trials – 2013- An overview provided by Roche
An Overview of Bayesian Adaptive Clinical Trial Design – 2012 – Berry Consultants
Adaptive design clinical trials: Methodology, challenges and prospect – 2010 – Indian Journal of Pharmacology