Maintaining adherence above 95% is a critical determinant of the effectiveness of Highly Active Antiretroviral Therapy (HAART), yet this is difficult for any patient to maintain during chronic therapy. Now a longitudinal study of 3,004 Spaniards who began a nelfinavir-containing regimen has demonstrated that even those who start off as excellent adherers may miss doses further down the line, and that this significantly affects outcomes measured a year later.
These new data were reported by the respected GEEMA study group, one of very few to have published randomised control trial evidence on interventions designed to support adherence to HIV therapy. Casado and colleagues prospectively reviewed patients beginning nelfinavir (both drug naïve and experienced) between December 1998 and January 2000. Virological suppression and adherence were evaluated during the first twelve months of treatment. Adherence was evaluated by a validated Simplified Medication Adherence Questionnaire (SMAQ) completed at 3, 6 and 12 months.
At baseline, median HIV viral load was 4.26 log and median CD4 was 267 cells. Seventy-eight per cent of the group were antiretroviral-experienced. Fifteen per cent were naïve to protease inhibitors, and thirty-five per cent had a prior AIDS diagnosis.
Three month adherence levels above 95% were associated with viral load suppression below 200 copies after twelve months. However, whilst 69% of the cohort reported adherence levels this high at month three, just 29% maintained this level throughout the twelve month follow-up period. Decreased adherence was significantly associated with viral load rebound; individuals whose adherence declined below 95% were four times more likely to experience rebound compared to those with greater than 95% adherence. Adherence was the main determinant of virological suppression, independent of baseline viral load or CD4.
As is clear from the general medical literature, these data demonstrate the need for adherence interventions to be part of routine clinical follow-up if they are to be effective.
Casado JL et al. Change in adherence level and outcome of HIV infection: the importance of the consistency of adherence to antiretroviral therapy. 42nd ICAAC, San Diego, September 27-30, 2002, abstract H-1707.