Attitudes in clinical trials.

Two important papers by Schwartz and Lellouch have drawn distinctions between explanatory and pragmatic attitudes to clinical trials, and between individual and collective ethics. The pragmatic approach accords with the widespread use of 'intention-to-treat' analyses, but recent research has started to explore models for non-compliance adjustment which seek an explanatory approach. Individual and collective ethics often co-exist, and standard approaches to randomization may provide the most satisfactory compromise.