Poor Adherence to Oral Psychiatric Medication in Adults with Bipolar Disorder: The Psychiatrist May have More Influence than in Other Severe Mental Illnesses

Objective: Medication adherence in bipolar disorder (BD) may be influenced by 6 self-reported dimensions: 1) high/low psychological reactance, 2) high/low internal health locus of control (HLOC), 3) high/low doctor HLOC, 4) pharmacophobia, 5) pharmacophilia, and 6) skepticism about a specific medication. This study in Spain, Argentina, and Venezuela included 142 outpatients with BD prescribed 320 psychiatric medications and 1230 other psychiatric outpatients prescribed 2134 medications. Methods: Logistic regression models included adherence for each psychiatric medication, measured by the Sidorkiewicz Adherence Tool as the dependent variable. The models provided adjusted odds ratios (ORs) of dichotomous independent variables: clinical variables and 6 self-reported dimensions. Results: ORs significant in both groups were: 1) high doctor HLOC (OR=1.87 in BD, OR=1.25 in other patients), 2) high psychological reactance (respectively OR=0.572, OR=0.798), 3) pharmacophobia (respectively OR=0.361, OR=0.614), and 4) skepticism about a specific medication (respectively OR=0.300, OR=0.556). Two ORs were only significant in BD patients: medication duration > 1 year (OR=0.449), and extreme polypharmacy (OR=2.49). The study included 104 BD patients prescribed 122 mood stabilizers and 136 other patients prescribed 140 mood stabilizers. Two ORs were significant for mood stabilizer adherence only in BD patients: high doctor HLOC and skepticism (respective ORs=2.38, OR=0.390). The study included 87 BD patients prescribed 97 antipsychotics and 417 other patients prescribed 458 antipsychotics. Four ORs were significant for antipsychotic adherence only in the BD group. Conclusions: Future studies of adherence to all/specific medications should explore the specificity/commonality of these dimensions, particularly doctor HLOC, in BD versus other psychiatric patients.