Background Patients with rheumatoid arthritis (RA) develop osteoporosis more frequently than healthy individuals. Bone resorption and formation are respectively increased and inhibited in patients with RA¹, and steroids negatively affect bone metabolism in both patients with RA and healthy individuals. The effect of reducing the steroid dose on bone metabolic markers in patients with RA has remained unknown.

Objectives To understand annual changes in bone metabolic markers in patients with RA and healthy volunteers and to identify bone metabolic markers for RA.

Methods We started the 10-year prospective cohort TOMORROW (TOtal Management Of Risk factors in Rheumatoid arthritis patients to lOWer morbidity and mortality clinical trial (registration number, UMIN000003876)) in 2010. We compared changes in urinary crosslinked N-telopeptide of typeI collagen (NTx) and serum osteocalcin (OC), which are markers of bone resorption and formation, respectively, in a total of 404 age- and sex-matched patients and volunteersbetween 2010 and 2011 (ΔNTx = NTx during 2011 – NTx during 2010; ΔOC = OC during 2011 – OC during 2010). We also investigated the effects of decreasing the prednisolone (PSL) dosage on disease activity (ΔDAS28) for NTx and OC in the patients.

Results The ΔNTx values were significantly lower in the patients than in the volunteers (-0.51 ± 29.4 vs. 7.41 ± 18.7 nmol; p=0.0013), whereas theΔOC values were significantly higher in the patients (0.94 ± 2.47 vs. 0.37 ± 1.62; p=0.0065). The change of PSL dosage negatively and positively correlated with ΔOC ((r=-0.227, p=0.001; Fig. 1) and ΔNTx (r=0.07, p=0.323; Fig. 2), respectively, in the patients, whereas ΔDAS28 did not significantly correlate with ΔOC or ΔNTx.

Conclusions A decrease in the dose of PSL respectively decreased and increased markers of bone resorption and formation in parallel among patients with RA. That is, bone metabolic makers were improved. However, bone metabolic makers and disease activity did not correlate. Thus, bone metabolic markers might degenerate even when disease activity is under good control. Decreasing the PSL dosage is important for bone metabolism in patients with RA.

References

1. Garnero P, Delmas PD. Noninvasive techniques for assessing skeletal changes in inflammatory arthritis: bone biomarkers. Curr Opin Rheumatol. 2004; 16:428-34.

Disclosure of Interest M. Tada Grant/research support from: Japan Osteoporosis Foundation grant 2013, T. Koike Speakers bureau: Takeda Pharmaceutical, Mitsubishi Tanabe Pharma Corporation, Chugai Pharmaceutical, Eisai, Abbott Japan, Teijin Pharma, Banyu Pharmaceutical and Ono Pharmaceutical, T. Okano: None Declared, Y. Sugioka: None Declared, K. Mamoto: None Declared, K. Inui: None Declared, H. Nakamura: None Declared