Measuring Adherence To Medication In Schizophrenia: The Relationship Between Attitudes Toward Drug Therapy And Plasma Levels Of New-Generation Antipsychotics.

Measuring Adherence To Medication In Schizophrenia: The Relationship Between Attitudes Toward Drug Therapy And Plasma Levels Of New-Generation Antipsychotics.

Int J Neuropsychopharmacol. 2014 Dec 7;

Authors: Yalcin-Siedentopf N, Wartelsteiner F, Kaufmann A, Biedermann F, Edlinger M, Kemmler G, Rettenbacher MA, Widschwendter CG, Zernig G, Fleischhacker WW, Hofer A

Abstract
BACKGROUND: Non-adherence to medication is still a major problem in the treatment of schizophrenia. The current longitudinal study investigated whether the patients' attitudes toward treatment correlated with the ratio of observed versus expected plasma levels of antipsychotic drugs as an objective measurement of adherence.
METHODS: Data of patients starting monotherapy with a new-generation antipsychotic (NGA) were collected 2, 4, and 12 weeks after the initiation of treatment. Next to the assessment of patients' attitudes toward medication by means of the Drug Attitude Inventory (DAI) the ratio of the observed versus the expected plasma level was calculated. Antipsychotic-induced side effects were evaluated by means of the Udvalg for Kliniske Undersogelser (UKU) Side Effect Rating Scale.
RESULTS: A total of 93 patients were eligible for statistical analysis. About half of the ratios of observed versus expected plasma levels ranged from 0.5-2 and were considered as normal, whereas the other ratios were considered as either too low (<0.5) or too high (<2). No consistent correlation between patients' attitude toward drug therapy and the individual ratios of observed versus expected plasma levels of medication was detected. This finding was not affected by side effects.
CONCLUSIONS: Our results highlight the importance of recognizing the complex nature of adherence to medication in schizophrenia patients. Importantly, we found no consistent correlation between subjective and objective measures of medication adherence. Therefore, monitoring adherence to medication remains a challenge in clinical practice.

PMID: 25522423 [PubMed - as supplied by publisher]