Controlled clinical trials and postmarketing experience

The evaluation of any therapy, i.e. pharmacotherapy or a psychotherapy follows a stepwise process. Marketing authorization will be granted by the authorities after successful completion of a series of controlled trials. But it is generally accepted that results of controlled clinical trials cannot be generalized automatically to routine treatment. Thus, a separate evaluation of therapy under conditions of routine treatment has to be carried out, i.e. postmarketing surveillance or evaluation of therapy in so-called phase IV. There is a variety of methods and designs in phase IV research, for example, recording spontaneous observations regarding adverse events, epidemiologic surveys, stimulated spontaneous observations, case control studies and cohort studies, database analyses, interviews or experimental studies on special questions. Drug utilization observation studies are of particular importance since they are a very frequent study type. There are drug-epidemiologic studies with non-reactive assessment methods collecting and interrelating information on patient, illness, prescription, course and outcome. A protocol describing purpose of study and methodologic procedure is scientifically indispensable. Results of a drug utilization observation study on venlafaxine show to what extent hospitalized patients differ from those in ambulatory treatment. This is true for example for history of treatment or severity of illness. It can, therefore, be inferred that results from one treatment setting or from a particular group of physicians cannot automatically be generalized to another.