HIV update - 20th February 2019

What you can do to prevent health problems

Preventing smoking, lowering cholesterol, controlling blood pressure and curing hepatitis C are the most important interventions needed to prevent ill health in people with HIV, according to a major American study.

While improvements to HIV treatment and care would prevent some cases of cancer, heart disease, liver disease and kidney disease, far more cases could be prevented by eliminating the well-known risk factors for these health problems.

Data came from over 180,000 people living with HIV in North America, between 2000 and 2014. People who had a heart attack, non-AIDS defining cancer, end-stage liver disease and end-stage kidney disease were compared with people who did not. The risk factors, both related to HIV and not, were assessed.

The researchers calculated the “population-attributable fraction”, in other words the proportion of cases that would be avoided in the population if a risk factor was removed.

Smoking increases the risk of lung cancer, anal cancer and oral cancer (all of which affected significant numbers of people in this cohort), as well as other cancers. In this study, 24% of cancers would have been prevented if nobody smoked. While damage to the immune system contributes to cancers in people with HIV, only 3% of cancers would have been prevented by CD4 cell counts never falling below 200 cells/mm³.

In relation to heart attacks, 37% would have been prevented by never smoking, 44% prevented by controlling cholesterol and 42% prevented by controlling blood pressure. While immune suppression also contributes to cardiovascular disease, only 6% of heart attacks would have been prevented by CD4 cell counts never falling below 200 cells/mm³.

End-stage liver disease can be a consequence of excessive alcohol intake – 35% of cases would have been avoided if guidelines for alcohol consumption had never been exceeded. Similarly, 16% and 30% of end-stage liver disease would have been avoided if nobody acquired hepatitis B and C, respectively. Damage to the immune system had more of an impact on liver disease than the other conditions – 19% of cases would have been avoided by CD4 cell counts never falling below 200 cells/mm³.

Turning lastly to end-stage kidney disease, controlling high blood pressure and cholesterol would have prevented 39% and 22% of cases, respectively. While diabetes is a common cause of kidney disease in the general population, it had less impact in this group of people with HIV. Preventing diabetes would have avoided 6% of cases of end-stage kidney disease. Uncontrolled viral load can lead to HIV-associated kidney damage, especially in African Americans. Maintaining viral load below 400 copies/ml would have prevented 19% of cases.

For each of the four health conditions the researchers looked at, addressing HIV-related risk factors would have had less effect than dealing with the ‘traditional’ risk factors doctors are already familiar with from their care of people who don’t have HIV. The study shows the importance of healthy lifestyles in living a long life with HIV.

For more information, read NAM's booklet 'A long life with HIV'.

More news on smoking

Two other interesting studies on smoking in people with HIV have recently been published.

One found that people living with HIV appear to metabolise nicotine at a faster rate than HIV-negative people. This could explain why people with HIV are more likely to become smokers and find it harder to quit. People who metabolise nicotine at a slower rate smoke fewer cigarettes, are less dependent on nicotine and are more likely to succeed in quitting smoking. This was an innovative study – other researchers should try to do the same experiment and see if they get the same results.

The other study found that frequent cannabis smoking is a risk factor for lung disease in men with HIV, in addition to cigarette smoking as a risk factor. It is well known that people with HIV have an increased risk of lung disease. This is partly because of the high rates of smoking among HIV-positive individuals, as well as damage caused by HIV and immune suppression.

The research involved both HIV-positive and HIV-negative men. During ten years of follow-up, men living with HIV who had smoked cannabis every week for at least a year were more likely to have lung disease due to an infection (33%) than men living with HIV who did not use cannabis (22%). Similarly, cannabis smokers were more likely to have bronchitis (21%) than men who did not smoke cannabis (17%).

In contrast, in the men who did not have HIV, cannabis was not linked to either form of lung disease. This suggests that people with HIV are especially vulnerable to lung disease caused by cannabis smoking.

For more information, read NAM's factsheet 'Smoking'.

Do gay men know that U=U?

In late 2016 and early 2017, a survey was run with gay, bisexual and other men who have sex with men living in New York City. They were asked: “If an HIV-negative man and an HIV-positive man have anal sex together without condoms, how much protection would the following strategies provide against HIV transmission?” Five strategies were presented.

• Daily pre-exposure prophylaxis (PrEP): 70% believed this provided “a lot of” or “complete” protection.
• The HIV-positive man maintains an undetectable viral load: 39% believed it offered “a lot of” or “complete” protection.
• Event-based PrEP: 17% believed it offered protection.
• Strategic positioning (the HIV-negative man limits himself to the top position and the positive man to the bottom position): 16% said this would give “a lot of” or “complete” protection.
• Withdrawal before ejaculation: 11% said this provided protection.

In fact, when PrEP is taken daily, it provides over 99% protection, while a sustained viral load provides 100% protection. In this study, just one in five men living with HIV had confidence than an undetectable viral load provided “complete” (rather than “a lot of”) protection.

While knowledge did not vary by age or ethnicity, men who did not identify as gay, men with less education and HIV-negative men were more likely not to know what an “undetectable viral load” was.

To read the results of a similar survey with Australian gay men, read HIV update from June 2018.

For more information, read NAM's factsheet 'Undetectable viral load and transmission'.