Biomarkers for BMD Changes Differ at Anatomic Sites in Osteoporosis With RA

Effective biomarkers of changes in bone mineral density (BMD) were identified at different anatomic sites in patients with osteoporosis secondary to rheumatoid arthritis (RA), according to study results published in Arthritis Research & Therapy.

Using the Kyoto University Rheumatoid Arthritis Management Alliance (KURAMA) cohort from May 2011, a longitudinal cohort study was conducted involving patients with osteoporosis and RA. In 2012, their BMD was measured at three sites: the lumbar spine, proximal femur, and distal forearm. The patients also underwent a clinical examination, serum testing, and urinalysis. Two years later, the same data were collected from the same patients. Inclusion criteria included meeting the 1987 or 2010 American College of Rheumatology/European League Against Rheumatism criteria for RA, a written informed consent, age >18 years, and the availability of a complete data set.

Of 379 patients enrolled in the KURAMA cohort, 214 were chosen for the final analysis. The average patient age was 63.2 years (range, 32-85 years), 91.1% were women (61.6% were older than 60 years and expected to be in menopause), median body mass index was 21.3 kg/m² (range, 12.3-30.0 kg/m²), and mean glycated hemoglobin was 5.65% (range, 4.6%-9.2%). Patients’ physical functioning, disease activity, and joint distraction were also assessed. In addition, the researchers noted current medication use, including biologic disease-modifying antirheumatic drugs (used by 31.3%), vitamin D (used by 37.3%), and osteoporosis medications (bisphosphonate; used by 31.3%). Mean observation time was 2.3 years.

Annual BMD changes measured at the lumbar spine, proximal hip, and forearm were -0.14±2.70, -0.46±1.63, and -1.14±1.85, respectively, with no significant differences seen among sites. Patients who experienced new fractures (n=15; 7%) showed lower BMD at the three sites compared with patients without fractures (P =.04, .02, and .001, respectively).

In the multivariate analysis, homocysteine was a significant predictor of BMD loss at the lumbar spine. At the proximal femur, BMD changes were predicted by anti-cyclic citrullinated peptide antibody (BMD loss) and use of bisphosphonates or vitamin D (BMD gains). BMD changes at the distal forearm were predicted by levels of tartrate-resistant acid phosphatase 5b (BMD loss) and by the use of bisphosphonates or vitamin D (BMD gains).

Study limitations included a small cohort for the identification of biomarkers for each anatomic site, the fact that decreases in BMD may not necessarily reflect bone fragility, data analysis from a single-center study, a relatively short follow-up period, and the omission of newer osteoporosis drugs for consideration.

“Practitioners should treat each anatomical site with different markers and prescribe osteoporosis drugs to prevent fractures for RA patients,” the researchers wrote.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Tomizawa T, Ito H, Murata K, et al. Distinct biomarkers for different bones in osteoporosis with rheumatoid arthritis. Arthritis Res Ther. 2019;21(1):174.