expected to HAART, assays of genetic mutations associated with antiretroviral resistance are also commonly used, and some studies suggest an improved outcome if drug doses are adjusted for measured serum drug concentrations (DHHS, 2004). In many patients, antiretroviral therapy fails to fully suppress the virus either immediately or after a period of success. In this event, altering some or all of the drugs in the prescribed regimen may be required (DHHS, 2004).
The central challenge of HAART is adherence, or the ability of an individual to consistently follow the prescribed treatment regimen. Adherence is crucial in the treatment of any illness; however, its importance is magnified in the treatment of HIV for two reasons. First, fully successful suppression of the virus in the blood requires very high levels of adherence. Second, poor adherence can contribute to the development of drug-resistant strains of the virus, which can then be transmitted to others. This results in reduced treatment effectiveness and options in those individuals who have never been treated for HIV before and thus constitutes a public health threat. The factors that influence an individual’s ability to adhere to HAART include the regimen itself, an individual’s personal characteristics, and the social environment of the patient (Ickovics and Meisler, 1997; Catz et al., 2000; Stone, 2002; Gebo et al., 2003).
The ability to fully adhere to a treatment regimen for any illness is almost never complete; in general, 80 percent compliance is considered adherent (Piliero and Colagreco, 2003; Rabkin and Chesney, 1999). Although rates of compliance of those with HIV on HAART are generally higher than those of individuals with other chronic illnesses, HAART requires unprecedented adherence of more than 90 percent to receive optimal benefit (Harrigan et al., 2003; Garcia de Olalla et al., 2002; Bangsberg et al., 2001; McNabb et al., 2001; Paterson et al., 2000). While adherence levels in clinical trials have been high, results in the clinical setting have not been as successful (Escobar et al., 2003). A number of studies using multiple methods to measure adherence in various settings and populations have indicated that patients’ adherence to HAART averages 70 to 80 percent. Significantly, the studies show that few individuals are able to achieve the adherence levels required to receive the maximum benefit from the medication (Golin et al., 2002; Liu et al., 2001; Bangsberg et al., 2000). The inability of large numbers of patients to achieve the high levels of adherence required for complete viral suppression underscores the need to develop and provide appropriate adherence support as a routine part of HIV care.
The second factor that must be considered in any discussion of adherence is its role in the development of drug resistance. Drug resistance can