4: Treatment Adherence

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CHAPTER 4 Treatment Adherence

EPIDEMIOLOGY

Studies suggest that rates of nonadherence with psychiatric treatment are alarmingly high (24% to 90%). In a large meta-analysis, with a pooled sample of over 23,000 patients, the mean rate of nonadherence was 26%.1

Rates of treatment adherence vary depending on the population, the diagnosis, and the pharmacological intervention. Particularly high rates of treatment nonadherence occur among those with psychotic disorders. This was made clear in the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) investigation, which reported high rates of treatment discontinuation (74%) among the intent-to-treat group of 333 patients, within 4 months.2 A majority of patients were unable to remain in treatment, largely due to inadequate efficacy of treatment or to intolerable side effects. Reasons for nonadherence are multiple, complex, and varied.

Data on nonadherence include the following: only 45% of patients referred for psychotherapy from a general hospital psychiatry outpatient department showed up for one or more appointments3; nonattendance rates for patients with scheduled medical appointments are high (19% to 28%); nonadherence with medical recommendations accounts for 5% to 40% of hospital readmissions; medication doses are delayed or omitted by 30% to 50% of patients; patients with chronic diseases take their medications as prescribed only half of the time; 20% of patients stop filling their prescriptions within 1 month of their issue; approximately one-fourth of patients do not inform their physician about having stopped their antidepressant medications4; and in a follow-up study of inpatients with suicidal ideation, 52% of patients were nonadherent with use of medications at 12 weeks.5

CLINICAL AND ECONOMIC IMPACT OF ADHERENCE AND NONADHERENCE

Clinical outcomes are directly related to treatment adherence, which in turn is related to resource utilization and to the economic burden of mental illness. Adherence with psychiatric treatments is associated with better outcomes, a lower relapse rate, improved adherence with treatment regimens for nonpsychiatric illness, and lower rates of hospitalization.68 Nonadherence has been associated with a greater risk of psychiatric hospitalization, use of emergency services, arrests, violence, victimizations, lower mental function, lower life satisfaction, and more prevalent use of substances.9 Rates of suicidal ideation are significantly greater among patients who are treatment nonadherent following hospitalization.5

Given the clinical impact of treatment nonadherence, the economic burden incurred through nonadherence is significant. Data derived from the Global Burden of Disease Study conducted by the World Health Organization, the World Bank, and Harvard University revealed that mental illness, including suicide, accounts for over 15% of the burden of disease in countries such as the United States.10 Additionally, since major depression is the leading cause of disability worldwide among persons age 5 or older, adherence to treatment can reduce the economic burden of mental illness.

Although little studied, the negative impact (including feeling frustrated, underappreciated, helpless, ineffectual, and “burned out”) of treatment nonadherence on clinicians should also be considered. Treating clinicians are affected when their patients are nonadherent with treatment. Future studies will undoubtedly measure the dispiriting impact when clinicians feel underappreciated and disaffected.

RISK FACTORS AND PREDICTORS OF TREATMENT NONADHERENCE

The reasons for treatment nonadherence are incompletely understood; however, they are undoubtedly multiple, com-plex, and varied. Any effort to understand this multifactorial challenge must include consideration of the elements in Figure 4-1 and Table 4-1.

Table 4-1 Factors That Affect Treatment Adherence

Most studies of adherence focus on specific patient populations that are typically categorized by diagnosis.

Affective Disorders

Symptoms of both mania and depression directly affect treatment adherence. In depression, persistent dysphoria and hopelessness may make a patient feel that his or her condition is irreparable and that treatment is futile. Psychomotor retardation, decreased energy, poor concentration, and diminished self-care lead to missed medications and appointments. With hypomania and mania comes an elevated mood and an invigorated energy level that most patients experience as positive; this makes many unmotivated to take medications that slow them down. When insight and judgment are impaired, some patients do not believe that they have an illness that requires treatment.

Studies of treatment adherence in those with depression demonstrate that adherence is highest when the perceived need for medication is greatest and the harmfulness of medication is low.11 In addition, a patient’s skepticism about the efficacy of antidepressant medications predicts early discontinuation of them.12 Reasons for nonadherence include discomfort about psychiatric diagnoses, denial of the illness, problematic side effects, fears of dependency, and the belief that medications were unhelpful following resolution of the acute phase of illness.13

In a study of African American and Caucasian patients with bipolar I disorder, more than half of all patients were either fully or partially nonadherent with medications, 4 months after an episode of acute mania.14 More than 20% denied having bipolar disorder, and they cited side effects of medications as contributing to their nonadherence. African Americans (more often than Caucasians) cited the fear of addiction and medication as a symbol of illness as reasons for nonadherence, which suggests that different cultures or ethnic groups may differ in their reasons for nonadherence.

Among patients with bipolar disorder, insight into treatment has been positively correlated with medication adherence, and adherence at the time of remission predicted adherence at one year.15