Does brachydactyly have a protective effect on the erosive changes in rheumatoid arthritis?

OBJECTIVE

Brachydactyly (BD) is a general term for inappropriately short fingers and/or toes. The author previously reported that a short metacarpal bone had a protective effect on the metacarpophalangeal joint of the same finger in rheumatoid arthritis (RA). The objective was to investigate the prevalence of BD in patients with RA and its potential effect on the phenotype, especially erosive changes.

METHODS

A total of 1524 Korean patients with RA were recruited. The presence of BD on hand radiographs, rheumatoid factor (RF), anti-cyclic citrullinated peptide antibody (anti-CCP), HLA-DRB1 shared epitopes (SE), risk haplotypes of peptidyl deiminase type IV (PADI4) and erosive joint stage, and smoking status, were determined.

RESULTS

The prevalence of BD was 7.9% (n=120) in our RA cohort. The types of BD were type A3 (79.2%), type D (15.0%), Kirner deformity (14.2%), and type E (6.7%). RA patients with BD had reduced erosion on hand radiographs (OR=0.57, 95% CI: 0.34-0.95, p=0.029) adjusted for age, sex, disease duration, smoking, RF, anti-CCP, SE, and PADI4.

CONCLUSION

BD is more common in RA patients than might be expected. BD may have a protective effect on erosive changes in RA independent of previously well-established risk factors such as seropositivity, SE, PADI4, and smoking.