Systematic qualitative review of the literature on data monitoring committees for randomized controlled trials

To systematically review the published literature on data monitoring committees (DMCs) for randomized controlled trials (RCT) and summarize information and opinions on best practice. This was part of the DAMOCLES project.

A systematic and comprehensive search of five online bibliographic databases was performed, identifying 4007 potentially relevant articles. These were assessed in two stages by the authors. The 84 most relevant articles were agreed and were supplemented with extracts from 16 books: ultimately, 100 sources were reviewed. A series of 23 questions plus subquestions were developed to structure the data extraction and interpretation process.

Much has been written about DMCs but by a rather small community of authors. The papers included some results of surveys, but were mainly opinion pieces based on the authors' beliefs, practices and experiences. There is a lack of empirical evidence for many aspects of DMCs. There was a great range of detail in the literature relating to the prespecified questions. It was generally agreed that interim monitoring of accumulating data was necessary in some form for most trials. Questions such as membership of the DMC featured widely in the literature with opinions and practice ranging from 3-20 members, of whom between none and all should be independent. There was a consensus that formal statistical methods should be used as tools to guide decision making rather than as hard rules. Conversely, topics such as the training and experience required for DMC membership were discussed in very few papers.

There is a consensus in the published literature in a number of areas, although there are many different models for structure and functions of a DMC. While uncertainty remains about some issues, it is strongly recommended that an explicit set of guidelines (Charter) is prepared for each DMC prior to the start of the trial specifying clearly how it will operate.