A prospective study of risk factors for nonadherence with antipsychotic medication in the treatment of schizophrenia

J Clin Psychiatry. 2006 Jul;67(7):1114-23. doi: 10.4088/jcp.v67n0715.


Objectives: This study aimed to prospectively identify the best single predictor and the best set of predictors of risk for nonadherence with anti-psychotic medication in the treatment of patients with schizophrenia.

Method: We used data from 1579 patients in a 3-year, prospective, naturalistic, nonrandomized, multisite study of schizophrenia patients conducted from July 1997 to September 2003 (U.S. Schizophrenia Care and Assessment Program). Adherence with any oral antipsychotic medication was assessed using patient-reported medication adherence and an indirect adherence measure based on medical record prescription information. Patients who reported poor medication adherence or had a medication possession ratio < or = 80% (percentage of days with prescriptions for any oral antipsychotic) during the first year after enrollment were defined as nonadherent (N = 296, 18.8%). Thirty-nine previously reported potential risk factors of nonadherence with antipsychotic medication were assessed at enrollment with valid and reliable measures. Risk factors represented patient-, environment-, and treatment-related domains, including sociodemographics, symptom severity, substance use, threat to safety of self and others, other illness-related factors, need for supervision, medication-related adverse events, and prior medication-utilization patterns.

Results: The best single predictor of future nonadherence was nonadherence during the 6 months prior to enrollment (odds ratio = 4.1, 95% confidence interval = 3.1 to 5.6, p < .001). The best set of predictors of nonadherence, ordered by strength of association, included prior non-adherence, recent illicit drug use, recent alcohol use, prior treatment with antidepressants, and greater patient-reported, medication-related cognitive impairment.

Conclusion: Nonadherence with antipsychotic medication is associated with a well-defined set of risk factors that can be used to identify patients who are predisposed to poor adherence.

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Antidepressive Agents / therapeutic use
  • Antipsychotic Agents / administration & dosage
  • Antipsychotic Agents / adverse effects
  • Antipsychotic Agents / therapeutic use*
  • Cognition Disorders / chemically induced
  • Cognition Disorders / diagnosis
  • Cognition Disorders / epidemiology
  • Drug Utilization
  • Female
  • Follow-Up Studies
  • Health Status
  • Humans
  • Longitudinal Studies
  • Male
  • Medical Records / statistics & numerical data
  • Prospective Studies
  • Psychiatric Status Rating Scales / statistics & numerical data
  • Risk Factors
  • Schizophrenia / drug therapy*
  • Schizophrenia / epidemiology
  • Schizophrenic Psychology
  • Treatment Refusal / statistics & numerical data*
  • United States


  • Antidepressive Agents
  • Antipsychotic Agents