Family link for cardiovascular disease

Rheumatoid arthritis and acute coronary syndrome have a shared association within families.

Rheumatoid arthritis is a chronic inflammatory disease that affects a person’s joints, causing pain and disability. Due to the inflammatory process, also internal organs, especially the heart, may also be affected over time. Rheumatoid arthritis is more common in older than young people, and it affects women more frequently than men.

It is known that people with rheumatoid arthritis are more at risk of getting cardiovascular diseases, including angina and heart attacks (sometimes called acute coronary syndrome, or shortened to ACS). This is thought to be due to the underlying inflammation in the body, which as well as causing rheumatoid arthritis, also affects the heart and blood vessels. Despite good inflammatory control with modern treatments, there is still a somewhat greater cardiovascular risk in people with rheumatoid arthritis than in people without the disease.

What did the authors hope to find?
The authors hoped to find out more about the links between cardiovascular risk and rheumatoid arthritis. They also wanted to investigate how much of the increased risk of getting acute coronary syndrome is caused by rheumatoid arthritis, and how much by other factors such as a person’s lifestyle or genetics.

Who was studied?
The study looked at over 8000 people with rheumatoid arthritis and their brothers or sisters (siblings). The siblings had to be full siblings, which means that they have both the same biological mother and father as the person with rheumatoid arthritis. Full siblings have similar genetic makeup, have been brought up in a similar way, and usually have similar adult lifestyles and environments. To be included in the study, the siblings had to be born within 5 years of each other.

How was the study conducted?
This was an observational study with prospectively collected data, which means that the authors used existing databases of continuously recorded patient data to look back and find people for each group. There was no interventional treatment given as part of this study.

The authors looked at nationwide registers available in Sweden to find the records of people with rheumatoid arthritis who had at least one full brother or sister not more than 5 years older or younger than them. They then matched these records with the records of up to five people from the general population that also had at least one full sibling born within 5 years of them, and then compared the risk of acute coronary syndrome for the people with rheumatoid arthritis and their full siblings against the people in the general population.

What were the main findings of the study?
The main finding of the study was that people who had a brother or sister with rheumatoid arthritis were themselves more at risk of having acute coronary syndrome. This increased risk could not be explained by traditional cardiovascular factors or by people’s socioeconomic background, which suggests that there is a direct link between rheumatoid arthritis and acute coronary syndrome.

Are these findings new?
Yes, this link has not been studied before.

What are the limitations of the study?
The study did not have information about people’s smoking habits or weight, which could have affected their risk of getting acute coronary syndrome. However, based on what is already known about the link between smoking and cardiovascular risk, the authors were able to take this into account when they analysed their data, and they believe that it is unlikely to change the results.

What do the authors plan on doing with this information?
The authors are planning more studies to look into what factors are shared between rheumatoid arthritis and acute coronary syndrome, and to investigate whether the link is genetic, or an external environmental factor in the way people are brought up.

What does this mean for me?
If you have rheumatoid arthritis, you have a higher risk of developing acute coronary syndrome than other people. This risk might also be higher for members of your immediate family, even if they do not have rheumatoid arthritis. These results suggest that you – and also potentially any full brothers and sisters you may have – might benefit from strategies to look after your heart and blood vessels. This includes stopping smoking, staying active, and eating healthily.

If you have any concerns about your disease or its treatment, you should talk to your doctor.

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Date prepared: May 2019
Summary based on research article published on: 20 February 2019
From: Westerlind H, et al. Siblings of patients with rheumatoid arthritis are at increased risk of acute coronary syndrome. Ann Rheum Dis 2019;78:683–687. doi:10.1136/annrheumdis-2018 214828

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