Strategic Timing of AntiRetroviral Treatment

When is the best time to start treatment for people with HIV?

What is this study about?

The aim of START was to determine if it is better for people with HIV to start anti-HIV drugs earlier than is current practice.

CD4+ cells form an important part of the immune system- they help coordinate the immune response by stimulating other immune cells to fight infection. HIV weakens the immune system by destroying CD4+ cells. So, the stronger the immune system, the higher number of CD4+ cells in the blood (CD4+ count). During the study the recommended guidance was for people with HIV start anti-HIV drugs when their CD4+ count drops to 350 (per microlitre).

Participants in START were people with HIV but with CD4+ count more than 500. The study compared the effects of starting anti-HIV drugs (antiretroviral therapy - ART) straight away when CD4+ count is more than 500 (immediate group) with delaying treatment until CD4+ count is less than 350 (deferred group) on disease progression and death in people with HIV. 

START Results

Starting HIV treatment straight away, rather than waiting until the disease has damaged the person's immune system, reduces the risk of developing serious illnesses. The results from the START trial were presented on the 20th July 2015 at the International AIDS Society conference in Vancouver and published in the New England Journal of Medicine.

Antiretroviral therapy is very effective at treating HIV, but it does have side effects. Until now it has not been clear whether it is better for a person with HIV whose immune system is still intact to wait until their immune system had been weakened by the disease before starting treatment for life, or to start is as soon as possible. START is the first large-scale randomised controlled trial to establish that starting antiretroviral treatment straight away benefits HIV-infected individuals regardless of the state of their immune system.

Follow up phase 

Following the results of START all participants were offered treatment if they were not already on antiretroviral therapy, and initially were all to be followed, as planned until 2016. Following additional funding the follow up has been extended to address another important question

'Are there long-term consequences from having delayed ART treatment?'

Only START can address this question reliably by comparing the immediate and deferred ART groups for rates of the START primary composite outcome for the calendar period 2016 to 2021.

The follow up data will provide valuable additional information on early HIV treatment. 

START infographic

Transparency Statement

Type of study

Randomised trial

Contact details

Who is funding the study?

The National Institute of Allergy and Infectious Diseases, USA.

When is it taking place?

Recruitment to the START study ended in December 2013. Following additional funding, participants will be followed to the end of 2021.

Where is it taking place?

START is taking place in 36 countries around the world, there are currently 20 sites in the UK.

Who is included?

To join START participants had a CD4+ count of at least 500 and had never taken antiretroviral therapy. Participants were randomly allocated to either start antiretroviral therapy immediatly, or wait until their CD4+ count drops to less than 350 before starting anti-HIV drugs.

The follow up phase is open to all the origianl START particpants