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EULAR: Obesity linked with increased rheumatoid arthritis incidence

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Substantial evidence supports an obesity and RA link

The new findings reported by Dr. Ljung that show obesity is a risk factor for developing rheumatoid arthritis are very consistent with what my associates and I reported last year using data collected in the Nurses Health Study (Ann. Rheum. Dis 2014;73:1914-22) as well as findings in several other recent reports (Ann. Rheum. Dis. 2014;73:1911-3). I think we can now say with confidence that obesity does increase a person’s risk for developing rheumatoid arthritis.

Mitchel L. Zoler/Frontline Medical News

Dr. Karen H. Costenbader

This firm link is important because it gives us practical information we can give to family members of patients with rheumatoid arthritis (RA) with implications for disease prevention. First-degree relatives of patients with RA often ask me what they can do to try to prevent themselves from also developing RA. For many years we had to tell them we didn’t know what they could do, but recently that’s changed. I tell relatives that while they can’t change their genes they can lose weight or not gain weight and that will reduce their risk, as well as certain other preventive steps such as not smoking. Many rheumatologists have been advocating smoking cessation for several years as a way to prevent RA onset, but talking about the risk for RA posed by obesity is only now starting to gain a similar place in prevention counseling.

Unfortunately we don’t yet have clear evidence that by taking these steps relatives of RA patients will better avoid developing the disease themselves, but nevertheless it is something positive they can do that has a reasonably good chance for success.

My associates and I have launched a pilot trial in which we are evaluating a risk calculator designed to assess the RA risk faced by first-degree relatives of RA patients, and then we are studying the efficacy of different counseling approaches to convey information about this risk. Preventive rheumatology is an exciting new facet of our specialty.

Dr. Karen H. Costenbader is a rheumatologist at Brigham and Women’s Hospital in Boston. She had no disclosures. She made these comments in an interview.


 

AT THE EULAR 2015 CONGRESS

References

ROME – Obese people had a 50% increased rate of developing rheumatoid arthritis compared with normal or underweight people, in a case-control study of more than 2,000 Swedish residents for which researchers used prospectively collected data.

The increased rate of developing rheumatoid arthritis (RA) conferred by obesity occurred in both women and in men, it was greatest in the subgroup of people who developed RA symptoms when they were age 50 years or younger, and it was greatest in the subgroup of people seropositive for anti-citrullinated protein antibodies (ACPA), rheumatoid factor (RF), or both Dr. Lotta Ljung said at the European Congress of Rheumatology.

The findings add to the growing body of evidence documenting obesity as a risk factor for development of RA, said Dr. Ljung, a rheumatologist at Umeå (Sweden) University.

She and her associates used data collected in two Swedish population-based cohorts followed prospectively, the Västerbotten Intervention Programme and the Northern Sweden portion of the MONICA project. The two databases included baseline and long-term follow-up data during 1985-2013 from more than 110,000 Swedish citizens, average age 52 years at baseline, and average body mass index of 26 kg/m2. The databases included 557 patients with incident RA, which appeared an average of 6 years following entry into their database, with 83% of the cases showing seropositivity for ACPA, RF, or both. The researchers matched these cases on a 3:1 basis with 1,671 controls without RA by their sex, year of birth, cohort, examination year, and region of residence in Sweden.

Dr. Lotta Ljung Mitchel L. Zoler/Frontline Medical News

Dr. Lotta Ljung

In an analysis that controlled for both smoking and education level, people who entered one of the databases with a BMI of 30 kg/m2 or higher, defined as obesity, had a statistically significant 50% increased rate of developing RA during follow-up, compared with people who entered with a BMI of less than 25 kg/m2, which corresponded to normal- or under-weight. Those with a BMI of 25-29.99 kg/m2, the overweight group, had a borderline statistically significant 20% increased rate of developing RA during follow-up, compared with the reference group, Dr. Ljung reported.

An analysis that examined the link between incident RA and baseline BMI as a continuous variable showed a 2% increased rate of incident RA for each 1-unit increase in BMI, but this relationship fell short of statistical significance after adjustment for smoking and education level. A second analysis that looked at waist circumference as a continuous variable showed a statistically significant 2% rise in RA incidence for each 1-cm increase in waist circumference at baseline after adjustment.

mzoler@frontlinemedcom.com

On Twitter @mitchelzoler

*Correction, 7/7/15: An earlier version of this article misstated information in the Vitals section.

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