Psychotherapy for patients with complex disorders and chronic symptoms. The need for a new research paradigm.

BACKGROUND

A clear distinction has been made between efficacy and effectiveness in relation to the methods of evaluation of new psychological treatments in psychiatry. Efficacy trials target patients with relatively pure conditions, who may not be representative of the patients who are usually referred for psychological treatment in a clinical setting. Few studies have explored the benefits of psychotherapy in patients with complex disorders and enduring symptoms.

AIMS

To explore the rationale for the distinction between efficacy and effectiveness, particularly in relation to outcome studies of patients with complex and enduring disorders.

METHOD

A narrative review with examples drawn from the literature, and an illustration of a recent naturalistic outcome study which combines features of both efficacy and effectiveness.

RESULTS

Studies of patients with complex and mixed disorders can be designed so that they retain internal validity, but also have external validity and are relevant to clinical practice.

CONCLUSION

Studies which evaluate psychological interventions should be carried out in populations of patients clinically representative of those who are likely to receive the intervention, should it be shown to be of benefit.