Research Profile - Following your HAART

Antiretroviral drugs now mean that HIV infection can be treated as a chronic health condition instead of the first step in a terminal illness, but lack of adherence to the therapy can put people at risk.

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In the early 1980s, a diagnosis of HIV was a death sentence. It was only a matter of time before the condition worsened to full-blown AIDS. But the introduction of antiretroviral drug therapy in the 1990s has meant the once-terminal disease is now a manageable condition. Highly Active Antiretroviral Therapy, HAART, involves taking a combination of three or four drugs that suppress the virus, allowing a person with HIV to have a good quality of life. However, because the therapy can require taking several pills at different times of day, adherence can be a problem, says Dr. Viviane Dias Lima, Senior Statistician with the British Columbia Centre for Excellence in HIV/AIDS. In this Q&A, Lima explains how non-adherence to antiretroviral therapy contributes to the spread of HIV.

Question: What do your studies indicate are the reasons for lack of adherence to HAART?

Answer: The epidemic of HIV has changed quite a lot. In the beginning, the toxicity of the drugs made it very hard to achieve complete adherence. Additionally, it was observed that most individuals getting HIV were gay men whose lifestyles sometimes made it complicated to adhere - if they smoked and drank alcohol or used illicit drugs. All this made them more prone to not adhere to therapy, because they had to remember to take the therapy at very specific times and there were lots of restrictions regarding taking the drugs. It was hard to comply. But the epidemic is changing; more individuals with addiction or mental health problems are now getting HIV and with that comes a (new) list of complications. If you have a mental illness you might not be in treatment all the time and your life could be a bit chaotic, which makes it difficult to comply.
 

Question: Why is adherence to antiretroviral therapy so important?

Answer: The drugs suppress the amount of the virus in your blood. The only way that you have an undetectable level of virus in your blood is if you take the drugs. We ask people with HIV to take at least 95% of all the drugs they're supposed to take; that is high adherence or full compliance. The HIV virus is smart – it reproduces quickly and it will try to escape from those drugs to reproduce and mutate. If you have adherence between 80% and 95% there is a risk of developing those mutations so that the drugs will not work any more for you. If you're taking less than that, you're going to have the virus in your blood and your immune system is not going to protect you and you're going to start to develop AIDS conditions.
 

Question: Do people realize if they have HIV and they don't adhere to the therapy they are putting themselves at risk for AIDS?

Answer: It happens. HIV still has a lot of stigma. For example, some people don't feel comfortable opening their bottles in the middle of work to say, 'Oh I'm taking my drugs now.' Lots of people don't want their co-workers to know that they have HIV. Some people may not tell their partners that they have HIV, so they have to take their drugs when no one sees it. If you're embarrassed or afraid, how can you take the medication when you're supposed to?
 

Question: You are funded by the Canadian Institutes of Health Research. Where are you focusing your research?

Answer: There are lots of things I would like to work on. One of these is to understand the impact of alcohol on adherence. Right now I'm preparing a manuscript that looks into alcohol use and incomplete adherence and negative treatment outcomes. If a person also uses illicit drugs, how much more complicated is it to adhere? I'm also working with mathematical modeling and, with that, adherence always is there, in terms of HIV transmission. I'm developing mathematical models for British Columbia and I'm working with the National Institutes of Health in the United States and, more recently, I have developed a model for Scotland to assess the impact of increased access to HIV therapy on their epidemic. Basically we are working together to test different hypotheses for how we can stop HIV from spreading.
 

Question: What role do mathematical models play in preventing HIV transmission?

Answer: I'll give an example. In BC, we showed that antiretroviral therapy can be used as a prevention tool, since the medication is going to make a person's virus go as low as possible. The lower their virus, the less chance they have to transmit HIV. Mathematical models, in my case, help me to make predictions into the future to see the impact of different interventions to stop the spread of HIV. We can use the past data to inform what might happen in the future. You can make a mathematical model to predict how many people have to be on treatment so we see a decrease in the number of new HIV infections.
 

Question: So that's the point of the mathematical model? To inform policy making?

Answer: Yes, and also to help you generate different hypotheses. Our hypothesis is that antiretroviral treatment can decrease HIV infection, and the mathematical model has shown that to be true. Now we're going to show in real data – because we're investing in putting more people on treatment in British Columbia – that the mathematical model was correct. We are just testing that hypothesis.
 

Question: When you say you put more people on antiretroviral therapy, that's for people that are already infected, correct?

Answer: Yes. Someone may be eligible for treatment, but may have to wait to get it. But the studies have shown that the earlier you start therapy, the greater is their benefit. There is the individual benefit because your quality of life is going to increase and you're not going to wait until you're very sick to come to treatment. In terms of public health, it's going to save money for the government because hospital beds, emergency services, all those things cost money. And society benefits from a decreased risk of infections.
 

By the numbers

• According to the Public Health Agency of Canada, the number of people living with HIV (including AIDS) continues to rise, from an estimated 57,000 in 2005 to 65,000 in 2008 – a 14% increase.
   
• Estimates of the annual number of new HIV infections range between 2,300 and 4,300.
   
• In 2008, men who have sex with men continued to comprise the greatest proportion – 44% – of new infections. The proportion of new infections among persons who inject drugs was 17%.

"The medication is going to make your virus go as low as possible. The lower the amount is in your blood, the lower the transmission rate."
-- Dr. Viviane Dias Lima