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Treatment nonadherence among patients with chronic illness is high, and bipolar disorder (BD) is no exception. Approximately 21% to 50% of patients with BD do not adhere to their recommended treatment regimen,1 which adds to the burden of illness and worsens prognosis.
Although treatment nonadherence is a concern with any psychiatric disorder, we focus on BD because of the high prevalence of the disorder, the lifelong nature of the illness, and its resulting disability. BD is challenging to treat even with motivated patients, and psychiatrists cannot count on individuals to follow their prescribed regimen just because they were told to do so. Choosing the best treatment for each patient is complicated, and as physicians, we need to learn how to connect with our patients, increase our insight into their concerns, and work collaboratively to find a treatment they can follow.
This article describes methods of assessing adherence, factors that affect adherence, and pharmacologic and psychosocial interventions to enhance adherence and improve outcomes.
What is adherence?
As the doctor-patient relationship and medical treatment evolved to become more patient-centered, so have the terms used to describe individuals’ treatment-related behavior. Compliance, a physician-centered term that mandates following instructions to achieve treatment goals, evolved to adherence, the extent to which a person fulfills their part of an agreed-upon treatment plan, followed by concordance, which describes a decision-making alliance between patient and provider that strongly considers patients’ input.
Adherence is considered adequate when it occurs at the minimum level necessary for the patient to respond to treatment and avoid relapse.2 Research on adherence in BD can be difficult to interpret because results may be influenced by:
- selection bias (patients who are adherent and insightful are more likely to consent to research)
- complications caused by polypharmacy and comorbidity
- investigators’ ability to choose the proper measure to delineate medication adherence attitudes and behaviors
- patients’ compliance with the adherence-enhancing interventions.2
Assessment methods. Several tools can be used to measure adherence to mental illness treatment. Attitudinal scales capture a person’s subjective feelings (such as being on a medication, insight, perceived strength of the therapeutic alliance, and level of stigma faced) and can reflect attitude change that may result from adherence-enhancing interventions. Adherence behavior scales may be convenient to administer in the office but tend to overestimate patients’ adherence (Table 1).3-7
Pill counts are inexpensive but patients can manipulate unused medication. Prescription refill counts are easy to obtain but do not confirm that the patient took the medication. Electronic medication monitors capture the time of specific doses and can calculate the adherence rate, but they are expensive and do not ensure that the medication was ingested. Measuring the drug in urine or blood is an objective measure of adherence and can serve as clinical guide to pharmacotherapy, but offers limited correlation with the amount of medication taken and is expensive. A combination of measures to estimate adherence may be best.2
Table 1
Tools for measuring adherence to medications
| Components/characteristics | Advantages | Disadvantages |
|---|---|---|
| Rating of Medication Influences3 | ||
| 19 items. Subscales: Reasons for adherence (prevention, influence of others, medication affinity), reasons for nonadherence (denial, dysphoria, logistical problems, label rejection, family influence, negative therapeutic alliance) | Valid, reliable. Correlates with other scales (DAI) | Developed on a population including only patients with schizophrenia treated with antipsychotics. Requires a trained rater |
| Drug Attitude Inventory4 | ||
| 30 items. Reflects patients’ attitudes about medication | Self-rated. High internal consistency. Accurately discriminates between adherent and nonadherent patients | Developed on a population including only patients with schizophrenia |
| Lithium Attitudes Questionnaire5 | ||
| 19 items. Areas of assessment: opposition to continue lithium, therapeutic effectiveness of lithium not accepted, difficulty with pill-taking routine, denial of illness severity, subcultural attitudes opposed to drug treatment, dissatisfaction with factual knowledge of lithium | Self-rated. Developed on patients with BD attending a lithium clinic. Good test/retest reliability for most items | The questionnaire is fairly long; shorter versions were adapted from original version |
| Medication Adherence Rating Scale6 | ||
| 10 items that assess medication adherence behavior, attitudes toward taking medication, negative side effects, attitudes toward psychotropic medication, measures adherence in past week | Self-rated. Validated on patients with various diagnoses, including BD. Correlates well with DAI, MAQ, and mood stabilizer drug levels (lithium and carbamazepine) | Validation methods may be limited by the other measures (for example, medication levels can be influenced by metabolism) |
| Brief Adherence Rating Scale7 | ||
| 3 items. Number of pills prescribed daily, days with no medication taken, and days with medication taken less than prescribed. Nonadherence defined as <70% of doses taken. Measures adherence in past month | Clinician–rated. Short. Good correlation with electronic medication monitoring. High internal reliability. Good test/retest reliability. Greater adherence on BARS correlates with lower psychotic symptom scores. Sensitive and specific in identifying nonadherence | Validation study only on patients with schizophrenia and schizoaffective disorder taking antipsychotics |
| BARS: Brief Adherence Rating Scale; BD: bipolar disorder; DAI: Drug Attitude Inventory; MAQ: Medication Adherence Questionnaire | ||