Prior opportunistic infections, symptom severity and low CD4 counts are all predictors of adherence. One patient described the progression of disease as "creating a sense of urgency for treatment." Another said: "As I first entered the study, I had a T-cell count below 10. I was at the hospital 20 some times The grim reaper was standing above me." (Erlon and Mellors, 1999).

Seeing an improvement in the immunological and virological indices used to monitor ART (CD4 cell counts and HIV viral load) may be a powerful incentive to maintain adherence (Kaplin et al., 1999). However, caution should be exercised in emphasizing a patient's improved laboratory indices without assurance that adherence is almost faultless. The value of these indices may improve in the short term, despite sporadic adherence and this may reinforce a patient's level of sub-optimal adherence.

Lack of symptoms (despite laboratory evidence of the need for ART) may have an adverse effect on adherence (Jones, et al., 1999). Most patients with untreated HIV infection have a median AIDS-free time of 11 years, and ART is often begun when patients have laboratory evidence of disease progression but are essentially asymptomatic and feeling well. In Uganda, the policy is to initiate treatment in patients with documented HIV infection and:

• WHO Stage IV disease, irrespective of CD4 cell count; or

• Advanced WHO Stage III disease, including persistent or recurrent oral thrush and invasive bacterial infections, irrespective of CD4 cell count or total lymphocyte count: or

• With a CD4 cell count of 200/mm³ or less for patients in WHO Stage I, II or III; or

• Tuberculosis with a CD4 cell count of 200-350/mm³.

3.5.2 Depression and severe anxiety

Depression and severe anxiety are both predictors of sub-optimal adherence (Hirschorn L et al., 1998). At some time in the course of their illness, most people with HIV, experience a psychiatric disorder (Buhrich and Judd, 1997). Depression and/or anxiety are reported in up to 70% of AIDS patients with symptomatic disease. Adherent patients demonstrate significantly less depression or other psychiatric disturbance (Catz et al., 1999).

As the disease progresses, HIV may have an impact on the central nervous system and affect memory. AIDS-related dementia (AIDS Dementia Complex) is a common finding in patients with advanced disease and is characterized by abnormalities in cognitive and motor functions. Although studies describing adherence and AIDS Dementia Complex were not found, cognitive deficits have a negative impact on adherence to ART (Meisler et al., 1993). Even when cognition is unimpaired, it is difficult to remember when to take medications.

3.5.3 Beliefs and knowledge

A patient's beliefs about their illness and the effectiveness of medication are predictive of adherence. A good level of understanding about HIV by the patient, a belief that ART is effective and prolongs life, and recognition that poor adherence may result in viral resistance and treatment failure (Wenger et al., 1999) all impact favourably upon a patient's ability to adhere. Conversely, a lack of interest in becoming knowledgeable about HIV and a belief that ART may in fact cause harm adversely affect adherence.