Does early intervention improve the prognosis in anorexia nervosa? A systematic review of the treatment-outcome literature.

OBJECTIVE: Early intervention has been suggested to be an important positive prognostic factor in the treatment of anorexia nervosa (AN). The treatment-outcome studies conducted thus far were systematically reviewed in search of evidence to confirm this suggestion.
METHOD: An extensive search was conducted for treatment outcome studies specifically addressing the prognostic value of the duration of the illness. Thirty-three follow-up studies of eating disorders and AN in particular were subjected to nine "best-evidence" criteria for methodological soundness. Six of these studies were found to meet all of the criteria and thus considered in greater detail.
RESULTS: In four of these studies, the duration of illness was not found to be related to the treatment outcome. This is presumably because of the low variability in duration of illness found in these studies. In the two remaining studies, a negative relation between duration of illness and the outcome of treatment was reported. As a result of methodological shortcomings and a lack of control for potentially confounding variables, however, the prognostic value of early intervention could still not be estimated on the basis of these studies. DISCUSSION: The prognostic value of early intervention in AN cannot be estimated on the basis of the treatment-outcome literature. Unfortunately, the duration of the illness and not the occurrence of early intervention is considered in most of the outcome studies of AN. In addition, a number of methodological shortcomings make it impossible to evaluate the prognostic value of early intervention.