Early stopping of prevention trials when multiple outcomes are of interest: a discussion.

In large prevention and screening trials, we want to answer multiple questions simultaneously. When monitoring prevention trials with multiple disease outcomes, composite measures may be useful, such as a count of important events, or a comparison of expected mortality. There are advantages to investigating multiple interventions in the same prevention or screening trial, using all-versus-none, factorial, or reciprocal control designs. In these situations it may be important to answer some questions early while others are still being investigated.