Compliance with treatment is notoriously low in psychiatric patients. Traditional methods of monitoring compliance, however, may underreport nonadherence to treatment. In this study, actual plasma levels at admission - which are ROUTINELY taken at the Dept Psychiatry of the Paracelsus Medical University - were compared to plasma levels that can be expected from the prescribed preadmission dosing regimen. This was done to give treating psychiatrists a quantitatively precise idea of how frequently they can expect their patients to have plasma levels that are below the level of medication as intended by the prescribing physician.

Context Noncompliance or incomplete compliance with psychopharmacological medication by psychiatric patients is a frequent risk and may be underreported by classical methods (e.g., pill counts or coloring additives).

Objective To determined the prevalence of incomplete compliance and/or faster-than average elimination of the medication by comparing actual plasma levels with those expected from the prescribed dosage under naturalistic routine conditions.

Design Forty-five day prospective routine survey.

Setting University acute inpatient clinic.

Participants All consecutive admissions for acute inpatient treatment from June 1, 2005 to July 15, 2005 who had been treated with antidepressants and/or antipsychotics.

Intervention Determination of plasma levels of all psychiatric medications and their comparison to the expected plasma levels, based on known preadmission dosing regimen and average pharmacokinetic data.

Main outcome measures The percentage of admissions with actual plasma level that were (a) more than 2-fold lower or (b) more than 2-fold higher than the expected plasma level or (c) differing only 0.5- to 2-fold from the expected plasma level.

Inclusion Criteria:

• eligible for psychiatric inpatient treatment

Exclusion Criteria:

• not eligible for psychiatric inpatient treatment

patients consecutively admitted for routine psychiatric inpatient treatment