RA Disease Activity Not Associated With Progression of Distal Interphalangeal Osteoarthritis

Rheumatoid arthritis (RA) activity, autoantibody status, and metacarpophalangeal erosions do not affect the prevalence or progression of distal interphalangeal osteoarthritis (DIP-OA), according to results published in Arthritis and Rheumatology.

These results indicate that inflammation plays a distinct role in the pathogenesis of RA and DIP-OA.

The study included participants with RA in the Swiss rheumatic disease registry (n=1988). The researchers used sequential radiographs to score participants’ DIP joints for the presence of central erosions and subchondral sclerosis (n=15,904). They also scored the severity of osteophytes and joint-space narrowing according to the modified Kellgren-Lawrence grade. They defined DIP-OA as ≥1 joint with Kellgren-Lawrence grade ≥2 and progression as an increase in total Kellgren-Lawrence grade.

At baseline, 60% of participants had DIP-OA. The researchers found that several factors were associated with the presence of DIP-OA, including age (OR, 1.09; 95% CI, 1.08-1.10), female sex (OR, 1.37; 95% CI, 1.08-1.74), and greater BMI (OR, 1.03; 95% CI, 1.00-1.06). However, neither anticitrullinated protein antibodies nor rheumatoid factor was associated with DIP-OA (OR, 0.72 [95% CI, 0.50-1.03]; and OR, 1.01 [95% CI, 0.74-1.38], respectively).

During a median 4.5 years of follow-up, 22% (174 of 789) of participants who did not have DIP-OA at baseline developed OA in at least 1 DIP joint. Among participants who had DIP-OA at baseline, 57% (680 of 1199) showed progression in their total Kellgren-Lawrence grade.

RA activity as measured by the Disease Activity Score of 28 joints based on the erythrocyte sedimentation rate (OR, 0.85; 95% CI, 0.75-0.96) and by erythrocyte sedimentation rate alone (OR, 0.98; 95% CI, 0.98-1.00) were negatively associated with the development of DIP-OA.

The researchers also noted that RA duration had no relevant size effect associated with DIP-OA progression (OR, 0.97; 95% CI, 0.96-0.99).

“The comprehensive radiographic assessment of DIP joints in this large RA cohort contributes to the understanding of DIP-OA and demonstrates that RA activity and autoantibody status are not involved in the radiographic course of DIP-OA,” the researchers wrote.

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Reference

Lechtenboehmer CA, Jaeger VK, Kyburz D, et al. Influence of disease activity in rheumatoid arthritis on radiographic progression of concomitant interphalangeal joint osteoarthritis [published online August 2, 2018]. Arthritis Rheumatol. doi: 10.1002/art.40684