Incomplete data in randomized dermatology trials: consequences and statistical methodology.

ABSTRACT

Randomized clinical trials can provide the highest level of evidence regarding the effectiveness of therapeutic interventions. When individuals in trials do not complete the planned treatment period it is often not possible to observe the desired outcomes, which results in incomplete data. Here we review various mechanisms which can lead to incomplete data, discuss the impact of these mechanisms, and present strategies for dealing with incomplete data. We discuss these issues in the context of clinical trials in dermatology and provide practical recommendations for planning and drawing conclusions from studies which could involve incomplete data.