The relation between autoantibodies and bone mineral density in patients with rheumatoid arthritis.
Arthritis Rheumatol. 2020 Dec 14;: Authors: Amkreutz JAMP, de Moel EC, Theander L, Willim M, Heimans L, Nilsson JÅ, Karlsson MK, Huizinga TWJ, Åkesson KE, Jacobsson LTH, Allaart CF, Turesson C, van der Woude D
OBJECTIVE: Autoantibodies such as anti-citrullinated protein antibodies (ACPA) have been described to induce bone loss in RA, which could also be reflected in bone mineral density (BMD). We therefore examined the association between autoantibodies and osteoporosis in two independent RA-cohorts. METHODS: Dual X-ray absorptiometry (DXA) of lumbar spine (LS) and left hip (LH) was performed in 408 Dutch and 198 Swedish early RA-patients during five and ten years respectively. The longitudinal effect of ACPA and other autoantibodies on several BMD measures was studied using generalized estimating equations. RESULTS: In the Dutch cohort, ACPA-positive patients had a significantly lower baseline BMD compared to ACPA-negative patients (LH: Estimated Marginal Means (Confidence Interval): 0.92 (0.91-0.93) versus 0.95 (0.03-0.97) g/cm2 (p=0.01)). In accordance, significantly lower baseline Z-scores were observed in the ACPA-positive group compared to the ACPA-negative group (LH: 0.18 (0.08-0.29) vs 0.48 (0.33-0.63) (p<0.01)). However, despite clear baseline differences, ACPA-positivity was not associated with greater decrease in absolute BMD or Z-score over time. Furthermore, there was no association between BMD and higher ACPA levels or other autoantibodies (RF and anti-CarP). In the Swedish cohort, ACPA-positive patients tended to have a higher baseline prevalence of osteopenia (p=0.04), but again, ACPA-positivity was not associated with more osteopenia or osteoporosis over time. CONCLUSION: The presence of ACPA is associated with a significantly lower baseline BMD, but not with greater BMD loss over time in treated RA-patients. These results suggest that ACPA alone do not appear to contribute to bone loss after disease onset when disease activity is well managed. PMID: 33314699 [PubMed - as supplied by publisher]