However, the results on this topic were difficult to interpret as only a small number of patients were included and the studies were limited to a single country. In addition, tenofovir alafenamide and dolutegravir were often used simultaneously in these studies, meaning that the individual effect of the antiretroviral drugs on weight dynamics could not be conclusively analysed.

The aim of the study was therefore to investigate the individual effect of different HIV drugs including tenofovir alafenamide and dolutegravir on body mass index (BMI) - with more people from more countries.

In total, the study analysed data from 14,703 people, of whom 7863 (54%) showed an increase in BMI of more than 7%.

Compared to lamivudine, which has not been shown to cause weight gain, the use of dolutegravir, raltegravir and tenofovir alafenamide was significantly associated with an increase in BMI of more than 7%. It was also shown that, compared to lamivudine, both dolutegravir and tenofovir alafenamide remained associated with an increase in BMI of more than 7%, even when the two substances were not combined. However, the increase in BMI was all the greater when dolutegravir and tenofovir alafenamide were taken at the same time.

In everyday clinical practice, tenofovir alafenamide is increasingly being used instead of tenofovir disoproxil fumarate and is often prescribed together with dolutegravir. The study has shown that both tenofovir alafenamide and dolutegravir are independently associated with an increase in BMI and that this is exacerbated when both drugs are taken at the same time.

Weight gain can lead to insulin resistance, an increase in cholesterol levels and high blood pressure. Future studies must now investigate whether weight gain in conjunction with antiretroviral drugs also leads to an increased risk of cardiovascular disease.

It is also still unclear whether tenofovir alafenamide actually leads to an increase in weight. It could also be that its predecessor tenofovir disoproxil fumarate simply has a weight-suppressing effect - and that this effect disappears when switching to tenofovir alafenamide.

Swiss HIV Cohort Study (SHCS)

What is a cohort study?

A cohort is a group of people who have experienced a common, long-term formative event. The HIV cohort study includes people with HIV in Switzerland.

What does the SHCS do?

The SHCS is a collaboration between hospitals and treating physicians who care for people with HIV. Since 1988, the SHCS has followed over 22,000 people with HIV, collected their health data and analysed it in scientific studies.

Why collect data?

The aim of research is to improve the quality of life of people living with HIV. Thanks to the research results, treating physicians can improve HIV therapy, for example by reducing side effects. Mental health needs also become more visible. By participating in the SHCS, people with HIV make a valuable contribution to improving medical care - for themselves and others.