Rheumatoid arthritis patients who tested positive for both rheumatoid factor and anticitrullinated protein antibodies showed a greater prevalence and size of bone erosions than did patients who came up negative for both in a prospective cohort study.
High-resolution peripheral quantitative CT revealed a prevalence of around 5.35 bone erosions per patient among 112 who were positive for both rheumatoid factor (RF) and anticitrullinated protein antibodies (ACPAs), compared with 2.49 in 69 who were negative for both of the autoantibodies. Another 29 patients who were ACPA positive and RH negative had 2.41 erosions, while 28 patients who were ACPA negative and RH positive had 2.00 erosions. The size of the bone erosion had a similar pattern, with the greatest volume observed in patients positive for both autoantibodies (7.66 mm3), followed by ACPA-positive patients (6.20 mm3), patients negative for both autoantibodies (3.32 mm3), and RH-positive patients (2.76 mm3).
The size of erosions was also associated with the presence and titer of rheumatoid factor in ACPA-positive but not ACPA-negative patients (Ann. Rheum. Dis. 2014 Aug. 12 [doi:10.1136/annrheumdis-2014-205428]).
"These observations suggest that RF may act as an enhancer of bone loss in patients with RA, and acts as an additive to ACPAs," wrote Dr. Carolin Hecht of the University of Erlangen-Nuremberg (Germany) and colleagues.
The study was supported by the Deutsche Forschungsgemeinschaft, the Bundesministerium fu¨r Bildung und Forschung, the Marie Curie project OSTEOIMMUNE, the TEAM and MASTERSWITCH projects of the European Union, and the IMI-funded project BTCure. There were no other conflicts of interest declared.