There are several lines of evidence showing that only a minority of patients with schizophrenia strictly adhere to their antipsychotic medication.[Tiihonen et al., 2011; Sendt et al., 2015; Ljungdalh, 2017] Several risk factors are associated with medication non-adherence in patients with schizophrenia, including illicit drug and alcohol use, antidepressant treatment, and greater levels of patient-reported medication-related cognitive impairment.[Ascher-Svanum et al., 2006]
One recently conducted systematic literature review of adherence rates in schizophrenia reported a wide range of adherence values ranging from 11–72%.[Ljungdalh, 2017] Part of the explanation for this range is the non-standard way in which adherence, and non-adherence, are defined and monitored in clinical trials.[Ljungdalh, 2017; Osterberg & Blaschke, 2005] This makes it challenging to develop and implement interventions to foster good adherence.[Ljungdalh, 2017; Osterberg & Blaschke, 2005]
References:
Ascher-Svanum H, Zhu B, Faries D, et al. A prospective study of risk factors for nonadherence with antipsychotic medication in the treatment of schizophrenia. J Clin Psychiatry 2006; 67 (7): 1114–1123.
Ljungdalh PM. Non-adherence to pharmacological treatment in schizophrenia and schizophrenia spectrum disorders – an updated systematic literature review. Eur J Psychiatry 2017; 31 (4): 172–186.
Osterberg L, Blaschke T. Adherence to medication. N Engl J Med 2005; 353 (5): 487–497.
Sendt KV, Tracy DK, Bhattacharyya S. A systematic review of factors influencing adherence to antipsychotic medication in schizophrenia-spectrum disorders. Psychiatry Res 2015; 225 (1–2): 14–30.
Tiihonen J, Haukka J, Taylor M, et al. A nationwide cohort study of oral and depot antipsychotics after first hospitalization for schizophrenia. Am J Psychiatry 2011; 168 (6): 603–609.