Compliance is a crucial determinant of the treatment outcome of any medical condition. Poor treatment compliance may affect the therapeutic alliance; create skepticism in both therapist and patient; create resistance; worsen the disease or the prognosis; and increase health care costs (Osterberg and Blaschke, 2005). Unfortunately, poor treatment compliance is often associated with blame, and noncompliant patients are sometimes punished with involuntary administrative discharge from treatment.
There are multiple indicators of treatment compliance that can be measured using direct or indirect methods. Among the direct methods, investigators and clinicians have used actual attendance to therapy sessions, direct observation or video-recording of sessions, measurement of medication blood levels, surrogate markers of medication, or expected changes in laboratory values. The indirect methods include self-reported compliance, pill counts, evidence or absence of expected side effects, and electronic monitoring devices. Unfortunately, the direct methods are expensive, and the indirect ones can be subject to biases.
In psychiatry, treatment compliance may be affected by factors associated with the therapist's characteristics, the service, the nature of the treatment and the patient's idiosyncrasies. The therapist may not adhere to the recommended treatment guidelines or the therapy manual. The services may affect compliance if they are hard to access or have long wait times, long lapses between appointments or complex administrative procedures. Treatments that involve complex procedures, are hard to follow, have unpleasant side effects, take a while to produce the desired effect, and are either unavailable or difficult to access may increase the chances of poor compliance. The characteristics of the patient, such as the presence of comorbid mental illness and substance use disorders (SUDs), can greatly affect treatment compliance.
EpidemiologyThe interest in psychiatric comorbidity increased with the publication of results from the Epidemiologic Catchment Area Study (Regier et al., 1990) and the National Comorbidity Study (Kessler et al., 1994). More recently, Kessler et al. (2005) showed that the relative magnitude of associations of having at least one substance use disorder in the past 12 months was significant for all but two mental conditions. The prevalence of mental health service use in the past year was only 41.1% and 38.1% for individuals who had any mental disorder or any substance use disorder in that time period, respectively (Wang et al., 2005).
Unfortunately, little is known about the proportion of individuals in the general population who use mental health services and actually adhere to their treatment plan. A survey of psychiatrists showed that 40% of their patients with SUDs had treatment compliance problems (Herbeck et al., 2005). Both clinical and nonclinical factors appeared to be associated with treatment compliance problems. Among the clinical factors, patients with low treatment compliance were more likely to have personality disorders, lower global assessment of functioning scores and medication side effects than those without treatment compliance problems (Herbeck et al., 2005).
It has been reported that the rates of completion of clinical trials for chronic medical conditions are only between 43% and 78% (Osterberg and Blaschke, 2005). It is likely that for those with psychiatric disorders, particularly with comorbid SUDs, this percentage may be even lower. According to a meta-analysis of medication compliance, the mean compliance rate for patients with physical disorders was 76%, whereas the ratio for patients taking antidepressants was 65% and 58% for antipsychotics (Cramer and Rosenheck, 1998). It has been estimated that medication noncompliance accounts for about 40% of re-hospitalizations of patients with schizophrenia (Weiden and Olfson, 1995).
The concurrence of mental illness and SUD seems to have a negative synergistic effect. It has been suggested that comorbid psychiatric disorders can further increase the risk of relapse and can have important implications for predicting treatment outcomes (Compton et al., 2003). The rates of treatment compliance among patients with SUD vary greatly, depending on the type of SUD and treatment, severity of the disorder, degree of psychosocial support, and the presence and severity of psychiatric comorbidity. Patients with only alcohol use disorders have significantly higher treatment retention rates (42%) than those with drug use disorders (20%) or combined alcohol and drug use disorders (26%) (McCaul et al., 2001). Furthermore, clinical trials of treatments for cocaine and other stimulant use disorders have difficulty retaining participants. In contrast, clinical trials of opioid agonist medications have better compliance rates (De Castro and Sabate, 2003).
