Adherence is the term used to describe the act of following a course of medication in exactly the manner it is prescribed. Adherence is sometimes also called compliance.

Wherever medication is given to treat or prevent a condition, it will only be effective if it is taken as intended. However, in HIV therapy, there are particular reasons why adherence is unusually important. The levels of adherence required for Highly Active Antiretroviral Therapy (HAART) to be successful are in the range of 90-95%, and thats much higher than levels which might be adequate with other types of medication. Moreover, HAART is typically taken long-term, and adhering well to therapy for any chronic condition presents its own challenges.

Poor adherence to HAART results in treatment failure, and faster disease progression in fact adherence has been shown to be the single most important factor in successful HIV therapy. The consequences of a failed HAART regimen may be far-reaching. HAART is prescribed in a manner designed to maintain a consistent attack on HIV. If you miss doses, or neglect any other aspect of your regimens requirements, this consistency will be lost. As drug levels in your body fluctuate, HIV is allowed to continue to reproduce. This ongoing replication permits drug-resistant strains to develop, and this can reduce the benefit youll gain from other antiretrovirals in the future. For more on resistance to HIV treatment, see the section titled Resistance.

Despite the importance of adherence in HIV therapy, our understanding of barriers and enablers of long-term high adherence is quite limited. In part, thats because it is a difficult area to investigate through commonly-used research methods. However, there is much to be learnt from the study of adherence in other disease settings.

Adherence is influenced by many complex factors. Some are quite practical, such as ensuring theres a reasonable match between the requirements of your regimen and your day-to-day lifestyle. Others are more cognitive and relate to how you perceive your health and medication whether you believe your treatment will do you more good than harm.

Some of these factors are more amenable to interventions designed to support adherence than others. However, health care professionals increasingly recognise that high adherence to HAART must be actively facilitated. The British HIV Association (BHIVA), in partnership with the Medical Society for Study of Venereal Diseases (MSSVD), have issued recommendations on how adherence should be managed within UK HIV clinics. The key principles which underpin their advice are that:

• Low adherence is difficult to predict and so HAART should not be withheld on the basis of assumptions about which patients will be high or low adherers.
• All patients prescribed HAART will require support if they are to adhere successfully.
• Adhering successfully to long-term therapy is more likely where patients have access to a wide range of supportive interventions.
• Interventions should be available throughout the time in which treatment is prescribed, and must therefore be integrated into routine patient care.

Reference

BHIVA Writing Group. Draft British HIV Association (BHIVA) / Medical Society for Study of Venereal Diseases (MSSVD) guidelines on provision of adherence support to individuals receiving antiretroviral therapy (2002). Available online at http://www.aidsmap.com/about/bhiva/bhiva_adherence.asp