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.
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