ORIGINAL INVESTIGATION Evaluation of factors influencing medication compliance in inpatient treatment of psychotic disorders Birgit Janssen & Wolfgang Gaebel & Martin Haerter & F. Komaharadi & Birgit Lindel & Stefan Weinmann Received: 15 February 2006 / Accepted: 14 April 2006 / Published online: 19 May 2006 # Springer-Verlag 2006 Abstract Rationale Short- and long-term compliance to prescribed antipsychotic drugs is of particular concern in regard to medication choice and treatment outcome in the care of psychotic disorders. Objective We evaluated patient-related and treatment-relat- ed factors associated with medication compliance in inpatients with a diagnosis of schizophrenia, schizoaffective disorder, or other psychotic disorder. Methods Within a naturalistic study in seven psychiatric hospitals, individuals with a psychotic disorder were assessed weekly on mental state, social functioning, side effects, and medication compliance. Logistic regression analyses were computed to assess patient and clinical predictors of medication compliance. Results We found a significant association between medica- tion compliance and substance abuse (OR 0.52, CI 0.32– 0.85), involuntary admission (OR 0.60, CI 0.41–0.89), history of aggressive behavior (OR 0.57, CI 0.38–0.85), and no school graduation (OR 0.59, CI 0.41–0.86). Individuals with pronounced paranoid or negative symptoms were also less compliant in taking their prescribed medication. There was no association between the initial inpatient antipsychotic medi- cation regime and patients’ compliance. Individuals who switched from a typical to an atypical antipsychotic drug were more compliant than those with their typical antipsychotic drug maintained. Those with higher medication compliance showed significantly greater improvement of their psychiatric symptoms during the inpatient stay. Conclusion Patient-related in addition to disease-related factors may strongly influence medication compliance. Besides more compliance with atypicals supposed by the literature, there may be a higher propensity for atypical drugs to be prescribed to those assumed to be more compliant. Keywords Schizophrenia . Compliance . Psychopharmacology Introduction Psychopharmacology of schizophrenia has improved in recent years with the development of new medications increasing the probability of finding an adequate drug for the individual patient. However, the large number of available treatment options makes the choice between various substances difficult. Most guidelines and reviews recommend choosing medications on aspects of effective- ness, tolerability, and patients’ preferences (Lehman et al. 2004; Davis and Chen 2003). As schizophrenia is a chronic disorder and psychotropic medication is generally adminis- Psychopharmacology (2006) 187:229–236 DOI 10.1007/s00213-006-0413-4 B. Janssen (*) : W. Gaebel : B. Lindel Department of Psychiatry and Psychotherapy, Heinrich Heine-University Duesseldorf, Bergische Landstr. 2, 40629 Duesseldorf, Germany e-mail: Birgit.Janssen@lvr.de B. Lindel e-mail: Birgit.lindel@lvr.de M. Haerter : F. Komaharadi Department of Psychiatry and Psychotherapy, University of Freiburg, Hauptstrasse 5, 79104 Freiburg, Germany S. Weinmann Department of Psychiatry II, University of Ulm, Ludwig-Heilmeyer-Str. 2, 89312 Guenzburg, Germany