ABSTRACT
Objective To investigate the prevalence of balance capacity declining and sarcopenia in patients with rheumatoid arthritis (RA),and to explore the effect of balance capacity declining and sarcopenia on spinal osteoporotic fracture (OPF)in RA. Methods A total of 963 hospitalized patients with RA and 158 age, gender-matched normal subjects from Jan. 2013 to Oct. 2015 were recruited from department of Rheumatology and Immunology, the first affiliated hospital of Anhui Medical University. Anteroposterior and lateral X-ray scanning of vertebral column(T5-L5)was conducted for every individual and semi-quantity method were used as the standard for determining vertebral OPF. Two hundred and sixty-seven RA patients and 156 control individuals were measured by bioelectrical impedance method for detecting skeletal muscle mass. Berg balance scale method was used to determine the balance capacity in RA patients. Statistical analyses were performed using statistical product and service solutions (SPSS) software (Version 17.0). Comparison of frequency among different groups was used by x2test. Ranksum test was used to compare the median of measurement data in different groups when the data were skewed in distribution. Linear correlation between two indicators was represented with correlation coefficient. Multivariate regression was analyzed by binary logistic Regression(Backward LR). Results ①The prevalence of vertebral OPF in RA was 15.1%(141/936), which was higher than that in the control group (6/158, 3.8%) ( x2=18.658, P<0.01). The incidence of sarcopenia in RA patients was 55.8%(149/267), which was significantly higher than that in control group (9.0%, 14/156) ( x2=91.176, P<0.01).②Compared to RA without spinal OPF, skeletal muscle mass of general body and every part of extremities were apparently decreased in RA with spinal OPF (P<0.05). Berg balance scale score in RA with spinal OPF (33±15) was lower than that in RA without spinal OPF (43 ±14) (t=4.150, P<0.01). ③Berg balance scale score in RA patients with sarcopenia was lower than that in RA without sarcopenia (37±14 vs 43±13, t=3.524, P=0.001) and the proportion of Berg balance scale score ≤40 in RA with sarcopenia was higher than that in RA without sarcopenia (50.8%,65/128 vs 29.9%,32/107, x2=10.477, P=0.001).Skeletal muscle mass of general body(18±4 vs 20±5,t=3.563,P<0.01)and every part of extremities in RA patients with Berg balance scale score ≤40 also were significantly reduced than that in RA group with Berg balance scale score >40(P<0.05). ④ Linear correlation analysis found that Berg balance scale score was positively correlated with skeletal muscle index (SMI)(r=0.299, P<0.01), skeletal muscle mass of general body (r=0.251, P<0.01), muscle mass of right upper limb (r=0.225, P<0.01), muscle mass of left upper limb (r=0.221,P<0.01).muscle mass of trunk(r=0.230,P<0.01),muscle mass of right lower limb(r=0.228, P<0.01), muscle mass of left lower limb (r=0.245, P<0.01) in RA. ⑤Logistic regression analysis (LR Backward) discovered that age (OR=1.075, P=0.002, 95%CI (1.028,1.124)] was the risk factor for spinal OPF in RA patients, while skeletal muscle mass index (SMI) [OR=0.649, P=0.020, 95% CI (0.451, 0.933)] and Berg balance scale score [OR=0.957, P=0.016, 95%CI (0.924, 0.992)] were protective factors for the occurrence of spinal OPF in RA. Conclusion Sarcopeniaand balance capacity declining are probably correlated with spinal OPF in RA.