ABOUT
The Cholesterol Treatment Trialists’ (CTT) Collaboration was established in 1994 after it was recognised that no single randomised controlled trial of a lipid intervention would have enough participants to enable reliable assessment of mortality outcomes or assess effects in particular types of patient.
To address this issue, the Collaboration conducts individual participant data meta-analyses of large-scale (1000 or more participants), long-term (two or more years) unconfounded, randomised controlled trials of lipid intervention treatments. To date the Collaboration has focused on assessment of statin therapy.
The Collaboration initially collected individual participant data on major vascular events, cancers and mortality as described in the original 1995 CTT protocol. The number of included trials grew over time to encompassing data from 28 major statin trials (approximately 175,000 trial participants) resulting in a series of publications which significantly impacted clinical guidelines.
In more recent years the Collaboration has collected and been analysing individual participant data on all other types of adverse events, supplemented by data on relevant laboratory values and co-medication recorded in large-scale statin trials according to a pre-specified plan published in 2016.
The aim of this project is to conduct comprehensive analyses of all the effects of statin therapy, both adverse and beneficial. This has involved a huge quantity of highly heterogeneous data, so to do this the Collaboration developed methods to convert the data into a single format using systems based on commonly used standards including the Clinical Data Interchange Standards Consortium Study Data Tabulation Model (CDISC SDTM) and the Medical Dictionary for Regulatory Activities (MedDRA).
FundinG
The work of the CTT Collaboration has been funded by the Australian National Heart Foundation, Australian National Health and Medical Research Council, British Heart Foundation, Cancer Research UK, European Community Biomed Programme, National Institute for Health and Care Research and UKRI Medical Research Council.
Although individual trials that are contributing data to the analyses were funded by the pharmaceutical industry, as well as by charities and government organisations (see details for each trial in the Participating Trials section), the CTT Collaboration has not received grant funding from industry.
data POLICY
Individual patient data from each contributing trial have been provided to the CTT Collaboration on the understanding that they would be used only for the purpose of the CTT meta-analyses and would not be released to others. Requests for such data should be made directly to the data custodians of each trial.
CTT Collaborators and other bona fide researchers are welcome, however, to suggest analyses in writing to the Secretariat. Where proposals are thought to be feasible and of potential interest, the Secretariat will conduct such analyses or, where appropriate, seek the views of the Collaboration on whether the analyses should be performed. If so, then the proposing scientist(s) will be invited to collaborate with the Secretariat in conducting and interpreting the analyses, and will be members of the Writing Committee in any papers describing the results of analyses.
Publication Policy
CTT Collaborators have an opportunity to contribute to analyses of the data, interpretation of the results, and drafting of the reports as members of a Writing Committee before they are published. CTT Collaboration analyses and associated papers are published in the name of the Collaborative Group.