(RxWiki News) While the exact cause of rheumatoid arthritis remains unknown, scientists are getting a better idea of what puts people at risk for this painful disease. It seems lifestyle may have a lot to do with that risk.
A recent study showed that smoking and obesity were linked to an increased risk of inflammatory polyarthritis, or arthritis that involves five or more joints. Rheumatoid arthritis is one type of inflammatory polyarthritis.
Results also showed that patients with diabetes had an increased risk of polyarthritis.
In contrast, drinking small amounts of alcohol and being from a higher social class were linked to a lower risk of developing inflammatory polyarthritis.
"Quit smoking and start exercising."
A team of researchers led by Professor Ian N. Bruce, MD, FRCP, of the Arthritis Research UK Epidemiology Unit at the University of Manchester, set out to study the relationship between lifestyle factors and the risk of inflammatory arthritis and rheumatoid arthritis.
For their study, Dr. Bruce and colleagues followed 25,455 participants from the European Prospective Investigation of Cancer, Norfolk, UK (EPIC-Norfolk) for about 14 years. Of these, 184 went on to develop inflammatory polyarthritis.
Results showed that smoking was associated with an increased risk of both inflammatory polyarthritis and rheumatoid arthritis in men, with a hazard ratio of 1.21 for every 10 years of smoking a pack per day.
A hazard ratio explains how frequently an event happens in one group versus another group. A hazard ratio of more than 1.0 means the event happened more in the first group than in the second. In this case, arthritis occurred more often among men who smoked a pack a day for 10 years.
Smoking was also associated with an increased risk of seropositive inflammatory arthritis in both men and women, with a hazard ratio of 1.24. Seropositive means that blood tests for arthritis were positive.
In addition, body mass index (BMI) – a measure of body fat using height and weight – was associated with seropositive inflammatory polyarthritis. Compared to normal weight participants, obese participants were more likely to develop inflammatory polyarthritis, with a hazard ratio of 2.75.
Compared to women with no children, women with two or more children had an increased risk of arthritis, with a hazard ratio of 2.81. However, breastfeeding was associated with a lower risk.
Results also showed that diabetes was associated with an increased risk of inflammatory polyarthritis (hazard ratio 2.54), while drinking small amounts of alcohol was associated with a lower risk (hazard ratio 0.86).
Higher social class was also associated with a lower risk of inflammatory polyarthritis, with a hazard ratio of 0.36. In other words, professional workers had a lower risk of inflammatory arthritis than manual laborers.
In a press statement, Dr. Bruce said, "The factors we studied give us vital clues to the early events in the process that ends in someone developing rheumatoid arthritis. They are also simple to ask about and can be used as part of a prevention program.
"Our new wave of funding from the Medical Research Council and National Institute of Health Research has allowed us to move forward to the next stage in our attempt to prevent the development of this distressing condition."
The research was funded by Arthritis Research UK, the European Commission 'Europe against Cancer' Programme, Cancer Research UK, Medical Research Council and the Stroke Association among others. The study was published March 16 in the Annals of the Rheumatic Diseases.
The authors declared no competing interests.