Medication non-adherence in bipolar disorder: Review of rates, demographic and clinical predictors

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