Background/Purpose:  To analyze the association between osteoprotegerin (OPG) and Dickkopf-related protein 1 (DKK-1) and the annual percent change (Δ%) in bone mineral density (BMD) in patients with tightly controlled rheumatoid arthritis (RA).

Methods:  Observational mixed-study. RA patients followed-up with a tight-control strategy were included. Bone densitometries were performed at baseline (T0) and follow-up (T1) and OPG and DKK-1 were measured by ELISA also in T0 and T1; additional clinical variables included disease activity measures, and treatment for RA and osteoporosis. Descriptive bivariate and multivariate analyses, stratified by gender, were performed.

Results:  We included 97 RA patients (70% female, with a mean age of 53 years, and 76% with low activity by DAS28); 95% were treated with DMARDs and 37% with anti-osteoporotic drugs. Mean lag-time between bone densitometries was 2.7 years. Most patients had their BMD improved. The mean Δ%BMD was +0.42% for lumbar spine, +0.15% for femoral neck and +0.91% for total femur. In men, baseline OPG was significantly associated with higher BMD loss (β coefficient -0.64) at femoral neck. In women, DKK-1 was associated with higher BMD loss at femoral neck (β coefficient -0.09), and total femur (β coefficient -0.11); however, DKK-1 was associated with lower BMD loss at lumbar spine (β coefficient 0.06).

Conclusion:  In tightly controlled RA patients, we have found no evidence of bone loss. Other factors than OPG and DKK-1, namely smoking and ACPA, may have a larger effect on bone mass than these molecules.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/effect-of-dkk-1-and-osteoprotegerin-on-bone-mass-in-tightly-controlled-rheumatoid-arthritis/