Rheumatoid Arthritis: 3 New Risk and Exacerbating Factors

February 13, 2018

Menopause, obesity, and bacterial infection all have a negative impact on RA, according to 3 recent studies.

References:

1. Mollard E, Pedro S, Chakravarty E, et al. The impact of menopause on functional status in women with rheumatoid arthritis. Rheumatology. 2018 Jan 29. doi.org/10.1093/rheumatology/kex526.2. Schulman E, Bartlett SJ, Schieir O, et al. Overweight and obesity reduce the likelihood of achieving sustained remission in early rheumatoid arthritis: results from the Canadian Early Arthritis Cohort Study. Arthritis Care Res. 2017 Nov 30. doi:10.1002/acr.234573. Sharp RC, Beg SA, Naser SA. Polymorphisms in protein tyrosine phosphatase non-receptor type 2 and 22 (PTPN2/22) are linked to hyper-proliferative T-cells and susceptibility to Mycobacteria in rheumatoid arthritis. Front Cell Infect Microbiol. 2018 Jan 25;8:11. doi: 10.3389/fcimb.2018.00011.

Highlights of 3 recent studies in rheumatoid arthritis (RA) include: (1) women with RA suffer a greater decline in physical function after menopause; (2) patients with early RA who are overweight or obese are less likely to achieve sustained remission; and (3) a strain of bacteria commonly found in milk and beef may trigger RA in those who are genetically susceptible.^1-3

An observational study investigated the association of menopause with functional status in women with rheumatoid arthritis.¹ The study included 8189 women: 2005 women (24.5%) were premenopausal (mean age, 39.7 years); 611 women (7.5%)-mean age, 50.7 years-transitioned through menopause during the study; and 5573 women (68.1%)-mean age, 62.3 years-were postmenopausal.

Women who were premenopausal had less functional decline, as measured by the Health Assessment Questionnaire, than women who were postmenopausal. These results remained strong even after adjustment for other significant factors. Use of hormone replacement therapy, pregnancy, and a longer reproductive life were all associated with reduced functional decline.
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"Further study is needed as to why women with RA are suffering a greater decline in function after menopause. Not only is this decline causing suffering for women, it is costly to both individuals and the healthcare system as a whole. Research is specifically needed on the mechanism connecting these variables with the eventual goal of identifying interventions that can maintain or improve function in postmenopausal women with RA," said lead author, Elizabeth Mollard of the University of Nebraska Medicine Center in Lincoln, NE.

A multicenter observational trial of patients with early RA treated by rheumatologists using guideline-based care included 982 patients: 315 patients (32%) had a healthy BMI, 343 patients (35%) were overweight, and 324 patients (33%) were obese.²

Within 3 years of diagnosis, 355 patients (36%) achieved sustained remission. Initial treatment did not differ by BMI category. Those who were overweight (hazard ratio [HR] = 0.75) and obese (HR = 0.53) were significantly less likely to achieve sustained remission than patients with a healthy BMI.
(©design36/Shutterstock.com)

"This is the largest study demonstrating the negative impact of excess weight on RA disease activity and supports a call to action to better identify and address this risk in RA patients," stated the researchers, led by Elizabeth Schulman, MD, of the Hospital for Special Surgery and Weill Cornell Medical School in New York.

Mycobacterium avium subspecies paratuberculosis (MAP) has previously been linked to Crohn's disease. Rheumatoid arthritis (RA) and Crohn's disease share the same genetic predispositions, and both are often treated with the same types of immunosuppressive drugs.

In this study, blood samples from 100 patients with RA were tested for single nucleotide polymorphisms; 78% of the patients were found to have a mutation in the PTPN2/22 gene, the same genetic mutation found in patients with Crohn's disease.³ Some 40% of the patients with RA tested positive for MAP.
(©Africa Studio/Shutterstock.com)

"We believe that individuals born with this genetic mutation and who are later exposed to MAP through consuming contaminated milk or meat from infected cattle are at a higher risk of developing RA. Understanding the role of MAP in RA means the disease could be treated more effectively. Ultimately, we may be able to administer a combined treatment to target both inflammation and bacterial infection," said senior author Saleh Naser, MD, of the University of Central Florida College of Medicine.