Clinical Edge Journal Scan Commentary: RA December 2021

Arundathi Jayatilleke, MD

Many people with rheumatoid arthritis (RA) have concomitant hand osteoarthritis (OA). This Swiss cohort study by Lechtenboehmer et al ¹ using a longitudinal registry of RA patients examined characteristics of RA patients who had progression of radiographic hand OA. Of over 1,300 patients who had radiographic distal interphalangeal (DIP) OA at baseline, a substantial fraction had progression of OA with osteophyte formation, joint space narrowing, and subchondral sclerosis. In subgroup analysis, biologic disease-modifying antirheumatic drug (bDMARD) use was associated with osteophyte formation, while of nearly 900 patients without radiographic OA at baseline, bDMARD use was not associated with development of DIP OA. While the authors postulate that this may be due to osteoanabolic effects of bDMARDs, in this real-world analysis the association does not imply a causative role for bDMARDs as additional confounders may exist and the onset/timing of progression is unknown. Still, the association deserves attention in controlled and long-term studies.

Another condition known to affect older adults is sarcopenia; in addition to aging, poor nutrition, lack of exercise, and autoimmune disease are thought to contribute to sarcopenia. RA is associated with an increased risk of sarcopenia. A cross-sectional study of cohort of Japanese women by Minamino et al. ² of RA examines the potential relationship between 25-OH vitamin D levels and sarcopenia. Participants were over the age of 60 and not taking vitamin D supplements. Low vitamin D levels, as well as age, 28-Joint RA Disease Activity Score (DAS-28), and health assessment questionnaire disability index (HAQ), were associated with the prevalence of severe sarcopenia, including the separate components of muscle mass, physical performance, and strength. Although this does not prove causation, the known decrease in vitamin D receptors in muscle nuclei with aging lends pathophysiologic support to vitamin D’s role in sarcopenia. Whether this plays a larger role in RA-related sarcopenia also remains to be seen.

Several recent studies have expanded our awareness of respiratory illness and exposure outside of cigarette smoking as potentially associated with RA risk. This single-center case control study by Kronzer et al ³ looked at respiratory disease diagnosis (based on ICD10 code) at least two years prior to RA diagnosis. Acute and chronic sinusitis, as well as pharyngitis, were associated with increased risk of RA, even adjusting for the known risk of smoking, raising the possibility of a role for the upper respiratory mucosa in RA pathogenesis. Whether this association is a sign of immune dysregulation instead or a result of other respiratory exposures is a question that should be further investigated given this growing body of evidence of respiratory involvement in RA pathogenesis.

In terms of other factors that influence the development of autoimmune disease, there is evidence of the involvement of the gut microbiome in RA pathogenesis, as well as public interest in the possibility of an optimal diet, such as the “Mediterranean diet” for control of arthritis symptoms. The recent Swedish crossover Anti-inflammatory Diet In Rheumatoid Arthritis (ADIRA) study by Turesson Wadell et al ⁴ examined effects of a “typical” and “anti-inflammatory” diet with whole grains, fruits, nuts, legumes, fatty fish, and probiotics in patients with RA. Prior work suggested that the anti-inflammatory diet was associated with lower RA disease activity and inflammatory markers. Only 44 patients completed the 10 week study, perhaps contributing to the lack of differences seen in functional measures, pain, fatigue, and morning stiffness at the end of the intervention. Changes in medications may have masked dietary effects in this small study and a longer study period may be necessary to assess effects. Given the lack of evidence in this area, further research is of course needed, but this study represents an initial attempt at rigorous examination and could be suggested to interested and motivated patients as generally safe.

References

1. Lechtenboehmer CA et al. Increased radiographic progression of distal hand osteoarthritis occurring during biologic DMARD monotherapy for concomitant rheumatoid arthritis. Arthritis Res Ther. 2021;23:267 (Oct 26).
2. Minamino H et al. Serum vitamin D status inversely associates with a prevalence of severe sarcopenia among female patients with rheumatoid arthritis. Sci Rep. 2021;11:20485 (Oct 14).
3. Kronzer VL et al. Association of sinusitis and upper respiratory tract diseases with incident rheumatoid arthritis: A case-control study. J Rheumatol 2021(Oct 15).
4. Turesson Wadell A et al. Effects on health-related quality of life in the randomized, controlled crossover trial ADIRA (Anti-inflammatory Diet In Rheumatoid Arthritis). PLoS One. 2021(Oct 14).