Comparison of Bone Metabolism among RA Population on Chronic DMARD Therapy and Those on anti TNF Blocker, Treatment Naive RA Patients and Normal Population

초록

Introduction Bone metabolism is disturbed in rheumatoid arthritis (RA) patients. Effects of oral disease modifying antirheumatic drug (DMARD) and anti Tumor necrosis factor (TNF) blockers on bone metabolism are still unknown. Objective We sought to compare the bone metabolism among RA population on chronic DMARD, anti TNF treatment, age and sex matched naïve RA patients and normal control. Methods Thirty-three seropositive RA patients (5 male, 28 female) were enrolled. More than 90% of patients had been receiving methotrexate with or without other DMARD for more than 6 months. Etanercept was administered, twice a week. Venous blood was drawn at baseline on DMARD therapy and 12-16 weeks after etanercept use, respectively. Treatment naïve RA patients who did not receive any DMARD treatment prior to the study were recruited along with normal control. Bone metabolism was assessed using bone specific alkaline phosphatase (BSAP) and sclerostin for bone formation and c-telopeptide (CTX) for bone resorption. Statistical differences between two groups were examined by independent samples T test. As RA on DMARD group and RA on TNF blocker group came from same population at different time point, their difference was assessed using paired samples T test. A p value of equal and less than 0.05 was denoted statistically significant. Results RA on DMARD group showed significantly lower level of BSAP compared to naïve RA population (p=0.044). Both BSAP and sclerostin increased after etanercept treatment, but was slightly significant only for sclerostin (p = 0.055). Serum CTX level was markedly lower in DMARD group than naïve RA population (p=0.008). It also increased after etanercept treatment which was significant (p = 0.026). Naïve RA population showed highest CTX level among all four groups. Conclusion In general, bone metabolism markers in RA on DMARD group showed lower serum level compared to naïve RA population which tended to incre