Cholesterol Treatment Trialists' Collaboration release of independent patient data to independent researchers
Executive summary
The Cholesterol Treatment Trialists’ (CTT) Collaboration is a long-established, investigator-led meta‑analysis consortium that holds pooled individual participant data (IPD) from large statin and lipid‑lowering trials and has used those IPD to publish major findings on efficacy and major outcomes [1] [2] [3]. Public reporting and the collaboration’s own documentation show efforts to extend and harmonise adverse‑event data and to request fuller trial datasets from sponsors, but the supplied sources do not document a general, open release of CTT’s independent patient‑level data for unrestricted access by independent external researchers [4] [5] [6].
1. The CTT’s data holdings and published IPD work
The CTT was created to pool large randomized trial datasets so that individual‑participant meta‑analyses could reliably estimate effects on mortality and major vascular events, and its landmark published analyses report pooled IPD from tens of thousands to hundreds of thousands of trial participants demonstrating consistent LDL‑lowering benefits [1] [2] [3]. The collaboration’s analyses have driven guideline and policy shifts because they are based on harmonised individual participant records rather than aggregate trial summaries [3] [7].
2. What the collaboration has shared and analysed so far
Historically, the CTT’s access and analytic scope have been focused on patient‑level data for cause‑specific mortality, major vascular events and site‑specific cancers, with primary publications reporting those endpoints and related efficacy measures; that limited scope was explicitly acknowledged in replies to calls for transparency [4]. More recent CTT work has undertaken harmonisation of adverse‑event data across trials and initiated reviews of all adverse events collected in participating trials, indicating an expansion of the kinds of IPD being assembled and analysed [5] [8].
3. Steps toward broader adverse‑event datasets — and remaining gatekeepers
Project descriptions and regulatory summaries show the CTT has asked trial sponsors and investigators to provide occurrence and timing of all adverse events, plus identifiers to link to existing records, and has published protocols for that extension, but these materials describe data aggregation and analysis rather than an unconditional public release of de‑identified patient datasets for third‑party use [6] [5]. The BMJ’s transparency campaign and commentary highlight that CTT’s prior access was limited and that independent re‑analysis proponents continue to press for open access to underlying participant‑level data [4].
4. Competing viewpoints and implicit interests
Supporters argue that CTT’s centralised, investigator‑controlled meta‑analyses are the most reliable way to estimate treatment effects because they standardise definitions and minimise bias in trial comparisons [7] [3]. Critics and open‑data advocates counter that independent external investigators should be permitted to re‑analyse de‑identified IPD to validate findings and explore harms, pointing to the collaboration’s past limits on adverse‑event analyses as a reason for broader access [4]. The sources also imply structural tensions: trial sponsors and original investigators remain necessary providers of granular adverse‑event records, creating practical and potential conflict‑of‑interest dynamics in who controls what data are available for secondary research [6] [5].
5. What the public record does — and does not — show about independent release
Based on the provided reporting, there is clear evidence the CTT holds and analyzes extensive IPD for major outcomes and is actively expanding its adverse‑event harmonisation work, and there are explicit requests to sponsors for more detailed adverse‑event data to be added to the CTT dataset [1] [5] [6]. However, none of the supplied sources documents that the CTT has broadly released its assembled patient‑level datasets to independent researchers outside the collaboration on an open, unrestricted basis; the debate documented in BMJ materials and project protocols centers on expanding and analysing data, not on a wholesale public data release [4] [6]. Where the records are silent, this report does not speculate beyond those documented steps.