According to a new study from Uppsala University, having a high BMI increases the risk of five major rheumatic diseases: arthritis, osteoarthritis, gout, psoriatic arthritis and inflammatory spondylitis. The researchers also found that BMI was a greater risk factor for gout and psoriatic arthritis in women than in men. This study will be presented in the journal Arthritis & Rheumatology. “The study results provide a greater understanding of the risks behind rheumatoid arthritis and show that low body weight can be used as an intervention to reduce the risk of developing rheumatoid arthritis,” Docent and researcher Veronica tells one. Department of Immunology, Genetics and Pathology at Uppsala University, who led the study.
Most rheumatic diseases are driven by inflammation in the body and mainly affect the joints, muscles and bones, but vital organs and vessels can also be affected. Symptoms of arthritis can include fatigue, swelling, joint pain, stiffness, and decreased range of motion. Previous studies have found associations between rheumatic diseases and high BMI (a type of ‘true’ body weight that also takes into account a person’s height).
However, it has not been fully investigated whether this association is due to the higher BMI actually causing the rheumatic disease, and not to patients with rheumatic disease having higher BMI on average for other unknown reasons. This is a common problem in epidemiological studies based on observational data.
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In the new study, the researchers attempted to solve the problem by using information contained in human genes instead. By using specific genetic variants that may be linked to high BMI, the researchers were able to show that men and women who have a genetic predisposition to high BMI also have an increased risk of developing gout.
“Although we have seen this association in the past, it is difficult to identify causal relationships between BMI and disease. But when we found that genes associated with higher BMI were also associated with higher risk of these rheumatic diseases, we were able to to conclude that BMI actually has an effect on the risk of developing rheumatoid arthritis,” says one.
The researchers used the same genetic method, called Mendelian inference, to study differences between men and women as well as possible differences in how BMI affects risk in women of childbearing age compared to women who have gone through menopause. This is known as randomization.
“For both gout and psoriatic arthritis, which is a common disease in patients with psoriasis, we observed that higher BMI was a stronger risk factor in women than in men. We also noted that BMI was associated with increased risk of developing osteoarthritis.” “Post-menopausal women have lower rates of childbearing than women of childbearing age,” explains Fatemeh Hadizadeh, a postdoctoral fellow at Uppsala University’s Department of Immunology, Genetics and Pathology and one of the study’s lead authors.
The researchers also found that a given increase in BMI did not result in a similar increase in the risk of developing gout among individuals with low, normal and high BMI. “We observed that an increase in BMI in normal-weight individuals resulted in a significantly greater increased risk of developing gout than an increase in BMI in already overweight and obese individuals. So the risk does not increase as much.” person who is already overweight. However, the higher your BMI, the higher the underlying risk of developing gout is always. It is interesting to study such non-linear effects from a molecular biological perspective to try to understand to understand why excess body weight increases the risk of disease,” says Torgny Carlsson, statistician at Uppsala University’s Department of Immunology, Genetics and Pathology and one of the study’s lead authors.