Health systems in the world's poorest nations are unlikely to rapidly develop the capacity to measure CD4 cell counts, viral loads, or resistance mutations until these tests become technically less demanding and less expensive. A regular supply of electricity is lacking in many areas in which AIDS is endemic and laboratory staff are scarce. In addition, the costs of most second line drugs remain prohibitively high for widespread use and, as a result, many countries have elected to have a restrictive drug formulary that limits the options for those in whom first line regimens fail. Thus, the development of cheaper drugs and diagnostic strategies remain urgent priorities for long term success in treating HIV and AIDS in resource poor settings.9,10
In the meantime, many countries and programmes are launching and scaling-up AIDS treatment with standard first line drugs and clinical monitoring algorithms. Most patients will thrive with this approach. However, since viral load is not routinely measured, early treatment failure (inability to suppress viral replication before clinical worsening) may not be detected. Patients with persistent viraemia during drug treatment will be at risk of accumulating an increasing number of HIV resistance mutations that may limit future therapeutic options. Once clinical failure ensues, the ability to select an optimal treatment regimen will be further limited by the inability to test for resistance.
For these reasons, prolonging the clinical efficacy of first line antiretroviral drugs regimens in resource limited settings is critical. Meticulous adherence to treatment, which has been shown in multiple studies to be the most important factor in delaying the development of drug resistance, must be emphasised.11-14
In the United States, the emergence of resistant strains, which now account for up to 15% of all new infections in certain cities, has little to do with the lack of sophisticated laboratory capacity but rather the lack of social support needed for vulnerable patients to adhere to demanding regimens (C del Rio et al, 8th annual conference on retroviruses and opportunistic infections, Chicago, IL, 2001).15
The global epidemic of multidrug resistant tuberculosis, fuelled by underfunded and poorly functioning systems of care, provides another sobering example of this phenomenon. Labelled a ticking time bomb,16
multidrug resistant tuberculosis has now been reported in more than 100 countries worldwide, accounting for over 20% of all cases in the mostly highly burdened areas.17
The consequences of erratic adherence to HIV therapy may be even greater because antiretroviral drugs are required for life and the risk of poor adherence is therefore much higher. Adherence to treatment for tuberculosis is highest with community based, supervised patient care.18,19
It seems reasonable to assume that treatment support will also be a cornerstone of HIV therapy.6,7