[Patient compliance--concept formation, assessment methods].

The topic of patient compliance is presented synoptically in a three-part review. In this first part the definition as well as the methods for the measurement of compliance are treated. Patient compliance is a problem that concerns every physician and patient. The phenomenon is not new and is the term for an old central problem of cooperation between physician and patient. Compliance is the intention to follow a medical advice. Noncompliance is common, occurs in all kinds of diseases and is expensive. There are several methods of different accuracy that allow to assess the extent of compliance or noncompliance, respectively. Direct and indirect procedures are distinguished. Questionnaires offered to patients, 'pill-counting', 'appointment-keeping' as well as registration of drug effects represent indirect methods. The direct approach includes measurement of drugs or metabolites in urine or serum. The next issues feature on factors determining compliance, interactions between physician and patient as well as methods for the determination of compliance.