Clinical research of sarcopenia and vitamin D deficiency in rheumatoid arthritis patients with osteoporosis / 中华风湿病学杂志

ABSTRACT

Objective To investigate the effect of sarcopenia and vitamin D deficiency on osteoporosis (OP) in patients with rheumatoid arthritis (RA).Methods Six hundred and forty-eight patients with RA were enrolled into the study,while 158 normal subjects were recruited as the control group.Bone mineral density (BMD) at total hip and lumbar vertebra 2-4 were measured by dual energy X-ray absorptiometry (DEXA),limbs skeletal muscle mass was determined in 267 patients with RA and 156 normal subjects by bioelectrical impedance method.Serum 25-hydroxy vitamin D [25(OH)D] levels were determined by electrochemiluminescence in 234 RA patients and 68 normal subjects.Clinical and laboratory features,daily dosage and duration of glucocorticoid (GC) were recorded.Numerical data and categorical data comparisons were analyzed using t test,x2 test,linear correlation analysis,single factor analysis of variance test and Logistic regression analysis test.Results ① Incidence of OP in RA (37.8％,245/648) was significantly higher than that in the controls (13.9％,22/158)(x2=32.712,P＜0.01).Incidence of sarcopenia was evidently higher in RA,compared with normal subjects [55.8％(149/267),9.0％(14/156),x2=91.176,P＜0.01].Percentage of sarcopenia was higher in RA with OP compared with RA without OP group [76.6％(49/64),39.3％(35/89),x2=20.848,P＜0.01].②Compared to control group,serum 25 (OH)D levels were significantly lower in RA group [(13.4±9.7) ng/ml,(22.4±6.3) ng/ml,t=9.063,P＜0.01].Rate of vitamin D deficiency iu RA was also higher than that in controls [80.8％(189/234),36.8％(25/68),x2=49.412,P＜0.01].③The differences of serum 25 (OH)D levels among different bone metabolic state groups at lumbar vertebra in RA (normal bone mass,osteopenia,OP) were statistically significant (F=6.263,P=0.003),whichrepresented a clearly decreasing trend along with the decreasing of serum 25 (OH)D levels (P=0.001).④Linear correlation analysis found that skeletal muscle mass indexes at limbs in RA were positively correlated with BMD and serum 25 (OH)D levels (P＜0.05).⑥Logistic Regression analysis revealed that sarcopenia (OR=4.373,P=0.002),age (OR=1.083,P=0.001) and duration of disease (OR=1.074,P=0.029) were the risk factors for occurrence of OP in patients with RA.Conclusion Sarcopenia generally exists in patients with RA,which is correlated with decreasing of serum 25 (OH)D levels,and also is the risk factor for the occurring of OP in RA.