To conduct a systematic search for all studies examining rates and demographic and illness-related determinants of medication non-adherence in bipolar disorder (BD).

A comprehensive literature search was undertaken of six English-language databases to identify published articles on medication non-adherence in BD from inception till December 2016. Any article, either a review or an original-research article was examined for its relevance to the subject. All such articles were manually searched to locate any further articles containing relevant information. Studies were included only if they had adequately described the patient sample, assessment methods and statistical procedures, presented their results systematically and their conclusions were congruent with the results.

The initial search yielded 249 articles on the subject; of these 198 articles were included. Of the 162 original-research studies, 132 had provided information on rates of medication non-adherence in BD. There was a wide variation in rates ranging from universal adherence (100%) to almost universal non-adherence (96%); this discrepancy was more due to methodological differences than true variations in rates. Notwithstanding the significant discrepancies in methodology, based on these 132 studies mean rates of 41.5%-43% and median rates of 40%-41% were obtained for medication non-adherence in BD. Rates of adherence with mood stabilizers were significantly lower than those for antipsychotics, or for medications of all classes. None of the demographic attributes were unequivocally linked to medication non-adherence in BD. Similarly, medication-related variables such as type of medications, doses, treatment regimens and side effects did not demonstrate consistent associations with non-adherence. Among clinical characteristics the presence of comorbid substance use disorder and absence of insight were the only two factors clearly linked to non-adherence in BD.

Medication non-adherence is prevalent in about a third to half of patients with BD. Demographic, illness and treatment related factors do not predict non-adherence with certainty.

• Medications
• Demographics
• Rates
• Non-adherence
• Illness characteristics
• Treatment variables
• Bipolar disorder

About half of the patients diagnosed with bipolar disorder (BD) become non-adherent during long-term treatment, a rate largely similar to other chronic illnesses and one that has remained unchanged over the years. Non-adherence in BD is a complex phenomenon determined by a multitude of influences. However, there is considerable uncertainty about the key determinants of non-adherence in BD. Initial research on non-adherence in BD mostly limited itself to examining demographic, clinical and medication-related factors impacting adherence. However, because of inconsistent results and failure of these studies to address the complexities of adherence behaviour, demographic and illness-related factors were alone unable to explain or predict non-adherence in BD. This prompted a shift to a more patient-centred approach of viewing non-adherence. The central element of this approach includes an emphasis on patients’ decisions regarding their own treatment based on their personal beliefs, life circumstances and their perceptions of benefits and disadvantages of treatment. Patients’ decision-making processes are influenced by the nature of their relationship with clinicians and the health-care system and by people in their immediate environment. The primacy of the patient’s perspective on non-adherence is in keeping with the current theoretical models and concordance-based approaches to adherence behaviour in BD. Research over the past two decades has further endorsed the critical role of patients’ attitudes and beliefs regarding medications, the importance of a collaborative treatment-alliance, the influence of the family, and the significance of other patient-related factors such as knowledge, stigma, patient satisfaction and access to treatment in determining non-adherence in BD. Though simply moving from an illness-centred to a patient-centred approach is unlikely to solve the problem of non-adherence in BD, such an approach is more likely to lead to a better understanding of non-adherence and more likely to yield effective solutions to tackle this common and distressing problem afflicting patients with BD.

• Non-adherence
• Bipolar disorder
• Attitudes
• Health-beliefs
• Treatment-alliance
• Familial influences
• Knowledge
• Stigma