Patient Adherence to Treatment Regimen
University of Pittsburgh
There is little doubt that a major contributor to health care costs is the failure of patients to adhere satisfactorily to treatment regimen. Indeed, the costs of nonadherence to pharmaceutical therapies alone has been estimated to exceed $100 billion a year (Grahl, 1994). The costs of nonadherence to other forms of treatment (e.g., diet, exercise, smoking cessation, and indialysis) have not been estimated, but given their contribution to disease management, they yield costs over and above those due to poor adherence to prescribed medication.
A portion of the costs of poor adherence lies in the necessity to further treat the complications or progression of varied diseases. For example, the person with hypertension who adheres poorly to treatment may progress to a stroke; the person with diabetes who adheres poorly may progress to limb loss, blindness, and/or cardiovascular disease. Both instances may lead to the necessity for rehabilitation and caretaking services as well as additional forms of treatment. Even in lifethreatening conditions, poor adherence has been observed. For example, poor adherence to treatment accounts for 25% of graft fail&es in organ transplantation (Rovelli et al., 1989). Even small deviations from the prescribed regimen can have significant clinical implications for the transplant patient. Indeed, poor adherence to treatment has been linked to unnecessary complications, as well as to disease progression in multiple diseases (Dunbar-Jacob & Schlenk, 1996).
More recently, poor adherence has been linked to the development of treatment-resistant organisms in infectious disease. The increase in tuberculosis in the past decade has been linked in part to variable adherence and/or to early cessation of antituberculosis medications (Bloom & Murray, 1992; Gibbons, 1992; Nolan, Aitken, Elarth, Anderson, & Miller, 1986). Similarly, poor adherence to antibiotic therapies has been associated with treatment resistance among children with otitis media (DeLalla, 1998) and has been suspected in a portion of disease-resistant staphylococcal and streptococcal infections (Schwarzmann, 1998). Most recently, there are dications that even slight deviations from prescribed antiretroviral medications may lead to the development of drug resistant strains of the HIV virus (Vanhove, Schapiro, Winters, Merigan, & Blaschke, 1996). Unfortunately, these drug resistant viruses are themselves transmissible.
The problems of poor adherence are also found in other conditions. For example, in primary prevention immunization rates are less than optimal in both the pediatric and geriatric groups. The failure to immunize leads to excess cases of such conditions as measles in childhood (Mason, 1992) and pneumonia among the elderly (Nichol, Margolis, Wuorenma, & VonSternberg, significant problem in rehabilitation where performance of therapeutic exercise looks similar to efforts to follow drug regimen (Dunbar- Jacob, 1998).
One factor that influences the degree of poor adherence found in research and clinical populations is the definition of adherence that is selected. Adherence can be defined in at least two general ways. The first is through the pattern of adherence problem expressed by the patient. The second is by the quantitative assessment that is made.