There remains considerable debate about the best time to start anti-HIV treatment. After the introduction of HAART in the mid-1990s, some experts believed that starting potent treatment very early - often referred to as the ‘hit early, hit hard’ approach - would reduce the risk of disease progression and possibly even eradicate the virus.

But as the long-term side effects of antiretroviral therapy became more apparent - and as it became clear that HIV eradication was unlikely using current drugs - experts began to favour delaying treatment until there were signs of disease progression. Of particular concern were metabolic complications such as body fat changes and elevated blood fat levels, which could increase the risk of developing heart disease.

Current European and US guidelines recommend commencing treatment when an asymptomatic person’s CD4 cell count falls into the 200 to 350 cells/mm³ range. Treatment should be started sooner if a person is experiencing symptoms of immune suppression, and should be considered at a higher CD4 count if a person has a high viral load (above 100,000 copies/ml).

Evidence from recent research, however, suggests that earlier treatment may be more beneficial. Several studies have shown that people are more likely to achieve HIV suppression below 50 copies/ml if their pre-treatment level is relatively low (below 50,000 copies/ml), and to attain a near-normal CD4 cell count if their pre-treatment count stayed relatively high.

The most common antiretroviral regimens used by people starting treatment today are less toxic than those used in the past, and appear less likely to cause long-term metabolic complications. Thus, some experts are once again beginning to favour earlier treatment, in the 350 to 500 cells/mm³ range.

Nevertheless, starting treatment earlier involves greater inconvenience and expense, the potential for reduced quality of life due to side-effects over a longer period of time and the risk of ‘using up’ available drugs sooner due to the development of drug resistance. In addition, there is still limited evidence that starting treatment earlier will provide long-term benefits in terms of slower disease progression or longer survival.

There are many factors to consider when deciding when to start treatment, including current viral load and CD4 cell count, overall health, pregnancy, co-existing conditions (such as hepatitis B or C) and risk factors (such as older age or smoking) that may increase the likelihood of serious complications while on therapy. For this reason, it is important, if possible, to receive care from healthcare providers who have experience treating people with HIV.

See Choosing a first combination for information on available drugs and current thinking about the sequence in which they could be used.