Prevalence of and risk factors for medication nonadherence in patients with schizophrenia: A comprehensive review of recent literature

Objective: Nonadherence to prescribed antipsychotic medications places patients with schizophrenia at a greatly increased risk of illness exacerbation and rehospitalization. Identification of risk factors for nonadherence is an initial step toward designing effective interventions. This article reviews recent literature on the prevalence of and risk factors for medication nonadherence in patients with schizophrenia. Data Sources: We searched the MEDLINE/ HealthSTAR and PsycINFO databases using combinations of the keywords risk factor(s), adherence, compliance, antipsychotic, neuroleptic, schizophrenia, and psychosis for articles published since 1980 that identified risk factors for medication nonadherence in schizophrenia patients. We included reports that (1) were published in English and (2) specifically examined risk factors for medication nonadherence. Thirty-nine articles met our selection criteria. Data Synthesis: Among the 10 reports that met a strict set of study inclusion criteria, we found a mean rate of nonadherence of 41.2%; the 5 reports that met a stricter set of inclusion criteria had a mean nonadherence rate of 49.5%. In the 39 articles reviewed, factors most consistently associated with nonadherence included poor insight, negative attitude or subjective response toward medication, previous nonadherence, substance abuse, shorter illness duration, inadequate discharge planning or aftercare environment, and poorer therapeutic alliance. Findings regarding an association between adherence and medication type were inconclusive, although few studies explored this relationship. Other factors such as age, gender, ethnicity, marital status, education level, neurocognitive impairment, severity of psychotic symptoms, severity of medication side effects, higher antipsychotic dose, presence of mood symptoms, route of medication administration, and family involvement were not found to be consistent predictors of nonadherence. Limitations of the published literature are discussed. Conclusion: Efforts to improve medication adherence in patients with schizophrenia should target relevant risk factors.