Synergistic effect of sarcopenia and osteoporosis on spinal osteoporotic fracture in patients with rheumatoid arthritis / 中华风湿病学杂志

ABSTRACT

Objective:To investigate the synergistic effect of sarcopenia and osteoporosis on the occurrence of spinal osteoporotic fracture (OPF) in patients with rheumatoid arthritis (RA).Methods:A total of 389 hospitalized RA patients and 156 age and sex-matched normal subjects (control group) were recruited. Dual energy X-ray absorptiometry (DEXA) method was used to measure bone mineral density (BMD) of lumbar spine and hip, and bioelectrical impedance method was applied to determine skeletal muscle mass of limbs. X-ray examination of spin was conducted and spinal OPF was diagnosed according to semi-quality method. Student's t test was used for comparison of measurement date between the two groups, χ2 test was used for comparison of intergroup rates, and Logistic Regression(Backward LR) method was used for multivariate Regression analysis of binomial classification data. Results:BMD of all test sites in RA patients was significantly lower than that in the control group ( P<0.01). The incidence of total OP in RA group was significantly higher than that in the control group [(32.9% vs 12.8%), χ2=22.706, P<0.01]. A total of 84 patients with RA developed spinal OPF, with an incidence of 21.6% which was higher than that in the control group [(3.8%), χ2=25.439, P<0.01]. The incidence of sarcopenia in RA was 54.8%, significantly higher than that in the control group [(9.6%), χ2=93.241, P<0.01]. The incidence of sarcopenia combined with osteoporosis in RA group (28.5%) was significantly higher than that in the control group [(5.8%), χ2=118.110, P<0.01]. Comparison of the incidence of spinal OPF in RA patients among groups with different bone mass (normal bone mass, osteopenia, osteoporosis) showed that the incidence of spinal OPF among these groups was statistically different ( χ2=43.373, P<0.01), and the incidence of spinal OPF increased along with the decrease of bone mass ( χ2=43.003, P<0.01). The incidence of spinal OPF in RA patients with sarcopenia (27.2%, 58/213) was significantly higher than that in RA patients without sarcopenia [(14.8%, 26/176), χ2=8.833, P=0.003]. All participants were divided into three groups group 1=no OP and sarcopenia, group 2=with sarcopenia or OP, group 3=both sarcopenia and OP. Difference of incidence of spine OPF in RA patients among three groups was statistically significant ( χ2=33.832, P<0.01), and the incidence of spinal OPF raised gradually in group 1 and 3, ( χ2=37.164, P<0.01). Incidences of sarcopenia, OP and spinal OPF in RA treated with glucocorticoid (GC) were higher than those in RA without GC ( P<0.05, P<0.01). Results of logistic regression showed advanced age[ OR(95% CI)=1.069(1.038, 1.101), P<0.01], usage of GC [ OR(95% CI)=3.169(1.679, 5.984), P<0.01] and sarcopenia combined with OP [ OR(95% CI)=2.113(1.430, 3.124), P<0.01] were risk factors for spinal OPF in RA patients. Conclusion:Incidences of sarcopenia, OP and spinal OPF in RA patients are higher than that in normal controls. Sarcopenia and OP have a synergistic effect on spinal OPF in RA patients.