Practical issues in data monitoring of clinical trials: summary of responses to a questionnaire at NIH.

A targeted poll was undertaken to compare and contrast models of data monitoring of randomized clinical trials sponsored by the National Institutes of Health. In an attempt to represent the institutes which conduct clinical trials, twelve individuals were selected and asked to respond to a questionnaire specifically prepared for this workshop. The response rate was 100 per cent. Most of the large trials sponsored by the institutes have independent, formally constituted data monitoring committees. There was one institute which does not have any data monitoring committees. The questionnaire is described in detail and a summary of the results is given.