Adherence to Treatment With Antipsychotic Medications Among Patients With Schizophrenia, Major Depressive Disorder, or Bipolar Disorder

Objective: To assess potential nonadherence among patients prescribed antipsychotic agents and to identify the use of illicit substances and/or nonprescribed medications in these patients. Methods: Urine samples that were submitted to the laboratory from patients prescribed antipsychotic medications were analyzed for the presence of antipsychotics and/or illicit substances (marijuana metabolite and/or cocaine metabolite) and nonprescribed opioid medications. Samples were classified as positive or negative for the antipsychotic if either parent and/or metabolite(s) were confirmed or not detected, respectively. Antipsychotic medications were tested using liquid chromatography/tandem mass spectrometry. Other drugs were tested using mass spectrometry confirmation following a presumptive positive screening result. Results: Among 3609 urine samples analyzed, 1561, 686, and 1362 samples had a listed diagnosis of schizophrenia, major depressive disorder (MDD), or bipolar disorder (BD), respectively. The proportion of urine samples that tested negative for a prescribed antipsychotic medication was significantly higher for both MDD (32.8%; odds ratio [OR], 2.1; 95% confidence interval [CI], 1.7-2.6) and BD (27.2%; OR, 1.6; 95% CI, 1.3-1.9) groups compared with the schizophrenia group (19.0%). The presence of illicit substances (ie, marijuana, cocaine) and/or nonprescribed medications (ie, opiate, synthetic opioid, benzodiazepine) was detected in significantly more samples from patients with MDD (42.7%; OR, 2.1; 95% CI, 1.7-2.5) or BD (35.2%; OR, 1.5; 95% CI, 1.3-1.8) relative to schizophrenia patients (26.5%). Conclusions: These results indicate that potential antipsychotic medication nonadherence and substance misuse may be even greater among patients with MDD or BD than those with schizophrenia.