Epidemiology of treatment failure: a focus on recent trends

As antiretroviral therapy has been refined with the development of more potent agents and simpler regimens, fewer individuals experience treatment failure. This review will highlight recent trends in treatment failure and virologic resistance in the developed world and resource-limited settings.

The goal of antiretroviral therapy in all individuals, regardless of prior treatment exposure or HIV drug resistance, is to achieve full suppression of viral replication with a viral load of less than 50 copies/ml. This goal has been made a reality by the development of newer agents and simpler, better tolerated regimens. Recent cohort studies have demonstrated improved virologic outcomes in the current antiretroviral era, with decreased rates of virologic failure and associated resistance. Improved tolerability has aided adherence, which remains a key determinant of treatment success. Cohorts in resource-limited settings report improved clinical and virologic outcomes as rollout of highly active antiretroviral therapy programs continues.

There has been a reassuring decrease in the frequency of virological failure and drug resistance in the modern highly active antiretroviral therapy era. This observation provides an important incentive to strengthen support of antiretroviral therapy programs to optimize virological outcomes, particularly in resource-limited settings in which access to newer agents and laboratory monitoring may be needed to ensure sustainable success.