Assessment of Distal Radius Bone Mineral Density in Osteoporosis Patients Receiving Denosumab, Including Those with Rheumatoid Arthritis and Those Receiving Oral Glucocorticoids

Recently, the osteoporosis treatment has attracted attention, and several drugs have been developed. Among these, bisphosphonates (BPs), parathyroid hormone (PTH) and anti-receptor activator of nuclear factor kappa B ligand (RANKL) monoclonal (MAb) denosumab (DMAb) are the major osteoporosis agents. Several studies demonstrated that the effect of osteoporosis agents is evaluated by lumar or hip dual energy X-ray absorptiometry (DXA). However, private clinic commonly use the radial DXA. On the other hand, rheumatoid arthritis (RA) is sometimes associated with osteoporosis but there is no established treatment approach. In addition, glucocorticoids (GCs) are often used in the treatment of RA and sometimes induce osteoporosis. The present study assessed the effect of DMAb on osteoporosis in patients divided into RA and RA + GC patients by radial DXA.

The therapeutic effect of denosumab was assessed in female osteoporosis patients using radial dual-energy X-ray absorptiometry (radial DXA) in three groups: those with postmenopausal osteoporosis (PO group), PO with rheumatoid arthritis (RA group), and PO with RA receiving glucocorticoids (RA + GC group).

In total, 427 PO patients 60 years of age or older with a young adult mean value of <70 %, as determined by radial DXA, were treated with denosumab. The denosumab treatment group comprised a PO group (n = 205), RA group (n = 156), and RA + GC group (n = 66). The control group comprised a PO group (n = 44) and RA group (n = 33) who received oral bisphosphonate. Bone mineral density (BMD) was determined by using radial DXA. The bone turnover marker type I collagen cross-linked N-telopeptide (NTx) was also measured.

Radial DXA revealed a significant increase in BMD in the denosumab treatment group but not in the bisphosphonate treatment group. The onset of an increase in BMD with denosumab was slower in the RA group than in those without RA. The effect of denosumab in preventing increased NTx levels was smaller in the RA and RA + GC groups than in the PO group. Adherence to denosumab treatment was statistically significantly greater than for bisphosphonate treatment.