Issues in data monitoring and interim analysis of trials (DAMOCLES)



The DAMOCLES study explored a range of issues around data monitoring committees (DMCs) for randomised controlled trials including: why and when are they needed; their roles and responsibilities; their structure and organisation; what information is required and who owns it; and decision-making and reporting requirements.   The study took a broad perspective, using several complementary research strategies to study behavioural and organisational aspects of DMCs and procedural issues of interim analyses. In brief, these included:

  • a systematic review of the published literature on DMCs;
  • a review of small group processes in decision-making;
  • surveys of plans and practices of DMCs in current and recently completed trials in the UK, and of relevant organisations' policies; and
  • case studies of DMCs where difficult decisions were faced and interviews with experienced DMC members.

Based on the results of the research, the group formulated a list of considerations that would be valuable for a DMC to address at the start of a trial. These were developed into a charter to describe systematically a DMC's operating practices and procedures.


Marion Campbell;




The DAMOCLES Study Group. A proposed charter for clinical trial 2005 data monitoring committees: helping them do their job well. Lancet 2005; 365: 711-22

Grant AM, Sydes M, McLeer S, Clemens F, Altman DG, Babiker A, Campbell MK, Darbyshire J, Elbourne D, Parmar M, Pocock S, Spiegelhalter D, Walker A, Wallace S. Issues in data monitoring and interim analysis of trials (the DAMOCLES study). Health Technol Assess. 2005, 9 (7)

Clemens F, Elbourne D, Darbyshire J, Pocock S and the DAMOCLES group. Data monitoring in randomised controlled trials: surveys of recent practice and policies. Clinical Trials 2005; 2: 22-23.

Sydes MR, Altman DG, Babiker AB, Parmar MKB, Spiegelhalter DJ and the DAMOCLES group. Reported Use of Data Monitoring Committees in the Main Published Reports of Randomised Controlled Trials: A Cross-sectional Study. Clinical Trials 2004; 1: 48-59.

Sydes MR, Spiegelhalter DJ, Altman DG, Babiker AB, Parmar MKB and the DAMOCLES group. Systematic review of Data Monitoring Committees in Randomised Controlled Trials. Clinical Trials 2004: 1: 60-79.

Walker AE, McLeer SK and the DAMOCLES Group. Small group processes relevant to Data Monitoring Committees: an overview of reviews. Clinical Trials 2004; 1: 282-296.

Additional information (files available to download)