Article type
Year
Abstract
Background: In the past decade there has been a worldwide initiative to make all clinical trials public. With the establishment of clinical trials registries, such as the US based ClinicalTrials.gov in 2000 and the Australian New Zealand Clinical Trial Registry (ANZCTR) in 2005, researchers and consumers are now able to find which clinical trials are taking place across all areas of health. This not only protects against publication bias and selective reporting, but also provides a valuable resource to evaluate trends in clinical trial activity.
Objectives: The aim of this study was to analyse the trends over time for clinical trial activity in Australia, including the number of trials across all disease areas, the types of interventions being evaluated, the size of clinical trials being conducted and the types of funding sources.
Methods: Data was sourced from ClinicalTrials.gov and ANZCTR for all registered intervention trials that had at least one Australian recruitment site. These registries combined cover 98% of registered trials in Australian sites (Dear, MJA 2011). The search results were exported as XML files and then converted into MS Excel spreadsheets, where they were cleaned and coded for analysis.
Results: Data were extracted for a total of 7891 registered trials. The total number of Australian trials registered annually on ANZCTR / ClinicalTrials.gov has steadily increased over the last nine years, from 567 in 2005 to 1028 in 2013. There was a 30% decrease in median sample size from 150 in 2005 to 84 in 2013. The proportion of industry trials has decreased from a peak of 55% in 2007 to 39% of trials commencing in 2013. Studies evaluating behaviour and lifestyle interventions have increased sixfold from 26 in 2005 to 185 in 2013. The top condition category studied was cancer, and mental health has overtaken cardiovascular disease as the category with the second most numerous trials.
Conclusions: A trend towards smaller sample sizes underscores the importance of meta-analyses to enable effects of interest to be detected. Other patterns in clinical trial activity may have important implications for systematic review planning and methodology.
Objectives: The aim of this study was to analyse the trends over time for clinical trial activity in Australia, including the number of trials across all disease areas, the types of interventions being evaluated, the size of clinical trials being conducted and the types of funding sources.
Methods: Data was sourced from ClinicalTrials.gov and ANZCTR for all registered intervention trials that had at least one Australian recruitment site. These registries combined cover 98% of registered trials in Australian sites (Dear, MJA 2011). The search results were exported as XML files and then converted into MS Excel spreadsheets, where they were cleaned and coded for analysis.
Results: Data were extracted for a total of 7891 registered trials. The total number of Australian trials registered annually on ANZCTR / ClinicalTrials.gov has steadily increased over the last nine years, from 567 in 2005 to 1028 in 2013. There was a 30% decrease in median sample size from 150 in 2005 to 84 in 2013. The proportion of industry trials has decreased from a peak of 55% in 2007 to 39% of trials commencing in 2013. Studies evaluating behaviour and lifestyle interventions have increased sixfold from 26 in 2005 to 185 in 2013. The top condition category studied was cancer, and mental health has overtaken cardiovascular disease as the category with the second most numerous trials.
Conclusions: A trend towards smaller sample sizes underscores the importance of meta-analyses to enable effects of interest to be detected. Other patterns in clinical trial activity may have important implications for systematic review planning and methodology.