HAART’s Achilles Heel: Why one-off adherence interventions are not enough

This article is more than 21 years old.

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.



In HIV, an individual who is ‘treatment naive’ has never taken anti-HIV treatment before.

longitudinal study

A study in which information is collected on people over several weeks, months or years. People may be followed forward in time (a prospective study), or information may be collected on past events (a retrospective study).

virological suppression

Halting of the function or replication of a virus. In HIV, optimal viral suppression is measured as the reduction of viral load (HIV RNA) to undetectable levels and is the goal of antiretroviral therapy.


Short for logarithm, a scale of measurement often used when describing viral load. A one log change is a ten-fold change, such as from 100 to 10. A two-log change is a one hundred-fold change, such as from 1,000 to 10.

randomised controlled trial (RCT)

The most reliable type of clinical trial. In a trial comparing drug A with drug B, patients are split into two groups, with one group receiving drug A and the other drug B. After a number of weeks or months, the outcomes of each group are compared.

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.