The research shows for the first time that cardiovascular risks affect autoimmune disease as a group of disorders, rather than selected disorders individually.

Earlier research has suggested associations between some autoimmune disorders and a higher risk of cardiovascular disease, and now,  a new study shows that nineteen of the most common autoimmune disorders seem to increase risk for developing heart disease.

Patients with autoimmune disease have a substantially higher risk (between 1.4 and 3.6 times depending on which autoimmune condition) of developing cardiovascular disease than people without an autoimmune disorder. This excess risk is comparable to that of type 2 diabetes.

The group of 19 autoimmune disorders accounts for about 6 percent of cardiovascular events. Importantly, excess cardiovascular risk was visible across the whole cardiovascular disease spectrum, beyond classical coronary heart disease, including infection-related heart disorders, heart inflammation, as well as thromboembolic and degenerative heart disorders, suggesting the implications of autoimmunity on cardiovascular health are likely to be much broader than originally thought. 

Furthermore, the excess risk was not explained by traditional cardiovascular risk factors such as age, sex, socioeconomic status, blood pressure, BMI, smoking, cholesterol and type 2 diabetes. The excess risk is particularly high among patients with autoimmune disorders under 45 years.

The findings were presented at the annual congress of the European Society of Cardiology in Barcelona and published in the Lancet.

The study was based on electronic health records from the United Kingdom's Clinical Practice Research Datalink (CPRD), a very large database of anonymized patient data from about one-fifth of the current UK population. Among 22 million patient records, the researchers assembled a cohort of patients newly diagnosed with any of the nineteen autoimmune disorders. They then looked at the incidence of  12 cardiovascular outcomes -- an unprecedented granularity that was made possible by the very large size of the dataset -- in the following years, and they compared it to a matched control group. The risk of developing cardiovascular disease for patients with one or more autoimmune disorders was on average 1.56 times higher than in those without autoimmune disease. They also found that the excess risk rose with the number of different autoimmune disorders in individual patients. Among the disorders with the highest excess risk were systemic sclerosis, Addison's disease, lupus and type I diabetes, the study showed.

"We see that the excess risk is comparable to that of type 2 diabetes. But although we have specific measures targeted at diabetes patients to lower their risk of developing cardiovascular disease (in terms of prevention and follow-up), we don't have any similar measures for patients with autoimmune disorders,” says study co-author Nathalie Conrad, PhD an epidemiologist in cardiovascular science at the University of Leuven in Belgium.

"We need to develop targeted prevention measures for these patients. And we need to do further research that helps us understand why patients with an autoimmune disorder develop more cardiovascular diseases than others, and how we can prevent this from happening."

The underlying mechanisms linking autoimmunity and heart disease are still poorly understood, she said. “The general hypothesis is that chronic and systemic inflammation, which is a common denominator in autoimmune disorders, can trigger all sorts of cardiovascular disease,” she said. “Effects of autoimmune disease on connective tissues, small vessels, and cardiomyocytes, and possibly some of the treatments commonly used to treat autoimmunity are also likely to contribute to patients' cardiovascular risk. This really needs to be investigated thoroughly.”