[Long-term follow-up: methodologic aspects in the interpretation of follow-up results. A presentation exemplified by anorexia nervosa].

Long-term follow-up investigations contribute to our knowledge and understanding of illnesses, their prognosis and the effectiveness of treatments. In the evaluation and interpretation of results of long-term follow-up studies many conceptual and methodological aspects have to be considered. Using the example of long-term follow-up investigations of anorexia nervosa some of the most important issues are discussed in a more general framework.