Confidence in the efficacy of using antiretroviral drugs to treat HIV infection has grown in the past year as a result of the prolonged survival of those randomly allocated to receive an additional drug in comparative controlled trials. HIV remains, however, the only serious infectious disease for which antimicrobial treatment is deliberately delayed. This is because infected subjects can often be symptomless for more than a decade in the absence of any treatment, and results from trials with the nucleoside analogue reverse transcriptase inhibitor zidovudine have failed to show any evidence for extended survival in those beginning treatment early compared with those who deferred treatment. The new confidence in currently available treatments, and in the prospects for new ones, inevitably leads to renewed questioning of the current strategy of waiting for signs of immune deficiency before electing to intervene. A new randomised controlled trial comparing strategies of early and deferred treatment is required to assess whether the time has come for intervention immediately after HIV has been diagnosed.

Recent evidence that combinations of antiretroviral drugs prolong survival compared with zidovudine alone (B Gazzard, third conference on retroviruses and opportunistic infections, Washington, DC, 1996; S Hammer, fifth European conference on clinical aspects and treatment of HIV, Copenhagen, 1995) and that the addition of the protease inhibitor ritonavir prolongs survival in late stage HIV infection (B Cameron et al, third conference on retroviruses and opportunistic infections, Washington, DC, 1996) has reopened the long running debate: when should antiretroviral treatment be started?

Since 1987, when zidovudine was shown to prolong survival in patients with AIDS,1 the key question of whether patients would be better off if treatment were started before the development of severe immune deficiency, reflected by clinical symptoms or low CD4 lymphocyte counts, has divided clinical opinion.2 3 4 …