Medication adherence in schizophrenia: factors influencing adherence and consequences of nonadherence, a systematic literature review

Background: Nonadherence to medication is a recognized problem and may be the most challenging aspect of treatment. Methods: We performed a systematic review of factors that influence adherence and the consequences of nonadherence to the patient, healthcare system and society, in patients with schizophrenia. Particular attention was given to the effect of nonadherence on hospitalization rates, as a key driver of increased costs of care. A qualitative systematic literature review was conducted using a broad search strategy using disease and adherence terms. Due to the large number of abstracts identified, article selection was based on studies with larger sample sizes published after 2001. Thirty-seven full papers were included: 15 studies on drivers and 22 on consequences, of which 12 assessed the link between nonadherence and hospitalization. Results: Key drivers of nonadherence included lack of insight, medication beliefs and substance abuse. Key consequences of nonadherence included greater risk of relapse, hospitalization and suicide. Factors positively related to adherence were a good therapeutic relationship with physician and perception of benefits of medication. The most frequently reported driver and consequence were lack of insight and greater risk of hospitalization respectively. Conclusions: Improving adherence in schizophrenia may have a considerable positive impact on patients and society. This can be achieved by focusing on the identified multitude of factors driving nonadherence.