The Differential Effect of Antibodies on Radiographic Progression in Rheumatoid Arthritis

The presence of bony erosions in patients with RA is a marker of disease severity and once present they are largely irreversible. Previous studies have shown that the presence of both rheumatoid factor (RF) and anti-cyclic citrullinated peptide (ACPA) antibodies is associated with erosive burden. The aim of our study is to determine the strength of relationship between antibody status and the presence of radiographic erosions at diagnosis.

A retrospective study of patients diagnosed with RA at a large university teaching hospital between January 1981 and December 2018. Clinical records were reviewed to determine antibody status, diagnosis date, duration of symptoms, DAS-28, age, ethnicity and whether the 1987 RA criteria was met. The presence of erosions at diagnosis were determined from plain film radiographs reports of hands and feet of patients. Statistical analysis was done using a Chi Square Model and Mann Whitney two-tailed U test.

There were 774 patients diagnosed with RA in our cohort. 367 (47%) of them were RF+/ACPA+, 87 (11%) were RF+/ACPA-, 66 (9%) were RF-/ACPA+ and 254 (33%) were antibody negative. 127 patients had erosions at the time of diagnosis. Patients in the double positive group had a significantly higher (p=0.003) erosion burden compared to the double negative group i.e. 21.5% in RF+/ACPA+ versus 11.0% in RF-/ACPA- group. The erosion burdens in RF+/ACPA- and RF-/ACPA+ groups were 13.7% and 12.1% respectively.

Our results show that patients RF+/ACPA+ have nearly two-fold higher incidence of radiographic erosions than patients who are RF-/ACPA-.