A recent Israeli study published in the International Journal of Clinical Practice examined the association between obesity and rheumatoid arthritis.
Obesity, one of the major consequences of the modern lifestyle, affects millions of people worldwide. It is a risk factor for a number of diseases including diabetes, cardiovascular disease, and cancer. Previous studies show that obesity worsens the rheumatoid arthritis disease activity score (a composite score that takes into account multiple factors such as joint swelling and pain and lab tests for systemic inflammation), decreases the quality of life of rheumatoid arthritis patients, and also reduces the rate of disease remission.1-5
However, other studies, rather intriguingly, indicate that obesity may protect joints from damage in early rheumatoid arthritis patients.6A more comprehensive study that followedmore than 200,000 women over the course of more than a decade found that being overweight or obese increased the risk for rheumatoid arthritis.7 A study carried out in Israel examined the link between obesity and rheumatoid arthritis published its results recently in the International Journal of Clinical Practice.8
Researchers gathered data on patients with rheumatoid arthritis from an Israeli health service database, and each patient with rheumatoid arthritis was compared with five age- and sex-matched controls from the same database. Data from 11,406 patients with rheumatoid arthritis and 54,701 age-and sex-matched controls was included in the study. Data gathered from the database included age, sex, socioeconomic status, body mass index, and smoking status. The study subjects were divided into three groups based on their socioeconomics status and into the following four groups based on their body mass indices: underweight, normal, overweight, and obese. Data from roughly the year 2000 and until 2015 were used.
What Factors Affect the Risk of Arthritis?
An analysis of the data showed that the proportion of obese individuals in the rheumatoid arthritis group was 33.4% compared to 31.6% in the control group. The proportion of smokers in the rheumatoid arthritis group was 33.5% compared to 29.7% in the control group. The association of obesity with rheumatoid arthritis was statistically significant. Both smoking and obesity were independently linked to rheumatoid arthritis. Males were less likely to suffer from rheumatoid arthritis than females. A medium socioeconomic status compared to high status was more likely to be associated with rheumatoid arthritis patients than the control group.
Is Chronic Inflammation to Blame?
One possible condition that could link obesity with rheumatoid arthritis is chronic inflammation. Several markers of systemic inflammation, including circulating C-reactive protein are higher in obese and overweight individuals. White adipose tissue, in addition to storing excess energy as fat, also secretes a plethora of proinflammatory and anti-inflammatory factors, which include leptin, adiponectin, and resistin among others. These modulate inflammatory processes and immunity, and therefore, chronic obesity may play an important role in the onset of autoimmune conditions such as rheumatoid arthritis. The results of this study appear to support this assumption.
The immobility that results from rheumatoid arthritis and the prescription of steroids for treating the condition can lead to weight gain, but the role of rheumatoid arthritis in contributing to obesity was not explored in this study. Further studies that further expand and delineate the nature of the association between obesity and rheumatoid arthritis could help develop better disease management strategies.
Written by Usha B. Nair, Ph.D.
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