| BackgroundRheumatoid arthritis(RA)is a chronic systemic autoimmune disease characterized with lesion of joint synovitis.Main symptom of RA is local and systemic destruction of bone joints,and sometimes associated with systemic osteoporosis(OP).OP is a systemic osteopathy characterized by reduction of per unit volume bone mineral density(BMD),degeneration of bone microstructure,decreasing of bone trabeculae,thinness of bone cortex and reduction of bone strength,which can increase bone fragility and occurrence of osteoporotic fracture(OPF).OPF is a main cause of disability and loss of labor force in RA patients,which results in tremendous mental,economic and living pressure in RA.Spine is one of the most common fracture sites.Obesity refers to abnormal fat distribution and/or excessive accumulation of nutritional and metabolic disorders.The commonly diagnostic indicators of obesity is body mass index(BMI)and waist circumference(WC).However,diagnostic criteria is influenced by race,age and gender,and the diagnostic criteria are different in different countries.BMI is not suitable for patients with muscular development and abnormal body fat distribution.Therefore,obesity is divided into simple obesity,oligomyosis and oligomyosis obesity.This paper mainly discusses correlation among different types of obesity,the disease activity of RA patients and occurrence of OP by evaluating the disease activity of RA patients,examining bone mineral density(BMD)of hip and lumbar spine and X-ray,calculating the BMI of RA patients,measuring body fat percentage,waist circumference(WC)and the quality of skeletal muscle in each part,and judging the existence of sarcopenia obesity,so as to provide theoretical basis for clinical prevention and treatment of RA.objectiveTo explore the correlation between different types of obesity and disease activity,OP in patients with RA.MethodThe research objects are a total of 418 RA patients hospitalized in the Department of Rheumatology,First Affiliated Hospital of Anhui Medical University from January2015 to December 2017 and 156 age-and sex-matched normal persons(control group).The diagnosis of all chosen RA patients conforms to ACR classification criteria for RA in 1987 and 2009.DEXA method is used to measure BMD of lumbar spine and hip in RA patients and control group,and bioelectrical impedance method is applied to determine skeletal muscle mass of limbs,body fat percentage,waist circumference,etc.Meanwhile,the general situation of RA patients were also recorded in detail including age,sex,height,weight,clinical and laboratory indicators.Result(1)Occurrences of different types of obesity in RA patients and control group.Median of BMI,PBF and WC of 418 RA patients and 156 normal control group suggested that the average BMI of RA patients was lower than that of control group(P<0.0001)while PBF was higher than that of control group(P=0.046).There was no statistical difference in WC between the two groups(P>0.05).There were significant differences in the composition ratio of different BMI groups between the two groups(x~2=15.017,P=0.002).There were obvious differences in the composition ratio of different sarcopenia obesity groups between the two groups(x~2=100.575,P<0.0001).Differences of PBF between RA patients and control groups was distinct(normal:elevated,158:254 vs 53:103),but there was no statistical difference between the two groups(x~2=0.928,P=0.335).Comparison of WC between two groups was clear(Normal:elevated,149:72 vs 101:55),but with no statistical difference(x2=0.293,P=0.588).(2)Comparison of BMI,PBF,WC and sarcopenia obesity among RA patients with different disease activity.The average BMI and WC were significantly different among RA patients with different disease activity(P<0.05).The higher disease activity was,the lower BMI and WC were.There was no significant difference in PBF between RA patients with different disease activity(P=0.542).There were remarkable differences in BMI and WC composition ratio among RA patients with different disease activity(x~2=12.820,P=0.046;x~2=6.501,P=0.039);PBF composition ratio among RA patients with different disease activity(normal:over-standard,5:13 vs 59:91 vs 98:146)and sarcopenia obesity composition ratio(normal:sarcopenia:obesity,sarcopenia obesity4:1:7:6 vs 37:22:39:51 vs 42:56:57:88),there was no significant difference(x~2=9.577,P=0.144).(3)Differences among all indicators of disease activity of RA patients in different BMI groups.The average ESR of RA patients in different BMI groups was significantly different(P=0.022),which showed that the higher BMI was inversely proportional to ESR.No statistical difference was manifested in other disease activity indicators between RA patients in different BMI groups(P>0.05).The composition ratio of joint function(I:II:III:IV)between RA patients in different BMI groups were these(4:37:19:5 vs 30:130:63:6 vs 10:55:25:5 vs 1:16:8:1 vs),but with no statistical difference(x2=7.479,P=0.587).(4)Comparisons of all disease activity indicators among RA patients in different PBF groups.There was no significant difference in disease activity indicators between RA patients in different PBF groups(P>0.05).(5)Comparisons of all disease activity indicators among RA patients in different WC groups.The average ESR level of RA patients in WC-elevated group was significantly lower than that in WC-normal group(P=0.022);there was no significant difference in other disease activity indicators among RA patients in different WC groups(P>0.05).(6)Comparisons of all disease activity indicators among RA patients in different sarcopenia obesity groups.The average ESR,DAS28 and HAQ levels of RA patients in different sarcopenia obesity groups were significantly different(P<0.05-0.0001).The average ESR,DAS28 and HAQ levels were higher in sarcopenia group and sarcopenia obesity group.The comparison of other disease activity indicators between different sarcopenia obesity groups was also made.The results showed no statistical difference(P>0.05).The composition ratio of joint function(I:II:III:IV)of RA patients in different BMI groups was compared(18:51:12:2 vs 5:42:23:5 vs 9:61:28:3 vs12:79:51:7 vs).The difference was statistically significant(x~2=22.500,P=0.007).The joint function of RA patients in sarcopenia group and sarcopenia obesity group was also worse.(7)The incidence of BMD and OP in different parts of RA patients in different BMI groups.The average BMD was obvious different among RA patients in different BMI groups(P<0.005-0.0001),which suggested that the BMI was in direct proportional to BMD.Comparisons of OP incidence in different parts of RA patients among different BMI groups showed that OP incidence in all parts of RA patients was significantly different(P<0.05-0.0001)except L4(P=0.078),and the incidence of OP decreased with the increase of BMI.(8)Comparisons of X-ray staging ratios of both hands and Sharp in RA patients with different BMI groups(emaciation:normal:overweight:obesity).There was no significant difference in X-ray staging ratios of RA patients(I-II-III-IV)(x~2=10.870,P=0.285).Sharp scores of RA patients among different BMI groups showed significant differences[44.50(8.75-126.25):34.5(7.00-102.75):21.00(1.00-80.00):15.00(2.75-71.50),z=8.325,P=0.040].Sharp scores decreased gradually with the increase of BMI.(9)The incidence of BMD and OP in different parts of RA patients in different PBF groups.There was no significant difference in BMD between different parts of RA patients in different PBF groups(P>0.05).The incidence of OP in different parts of RA patients among different PBF groups revealed that the overall incidence of OP in normal PBF group was significantly lower than that in elevated PBF group(53/162,32.7%vs 84/248,33.9%,x~2=7.077,P=0.029),while the incidence of OP in neck part(30/161,18.6%vs 33/247,13.4%,x~2=8.023,P=0.018)in normal PBF group was significantly higher than that in elevated PBF group.There was no significant difference in the incidence of OP in other parts among different PBF groups(P>0.018).05).(10)Comparisons between X-ray staging ratios of both hands and Sharp of RA patients between different PBF groups(normal:elevated).There was no significant difference in X-ray staging ratios of RA patients between different PBF groups(I-II-III-IV)(x~2=4.235,P=0.236).There was no significant difference in Sharp scores between different PBF groups(normal:elevated)in RA patients(z=1.337,P=0.181).(11)The incidence of BMD and OP in different parts of RA patients in different WC groups.As to BMD,there was no statistical difference(P>0.05)in different parts of RA patients in different WC groups.The incidence of OP in different parts of RA patients in different WC groups showed that the incidence of OP in total hip(33/151,21.9%vs 7/76,9.2%,x2=6.238,P=0.044)and L3(33/152,21.7%vs 8/76,10.5%,x2=7.039,P=0.030)in normal WC group was significantly higher than those in elevated WC group.There was no significant difference in the incidence of OP in other parts of WC groups(P>0.05).(12)Comparisons of X-ray staging ratios of both hands in RA patients between different WC groups with Sharp(normal:elevated).There was no significant difference in X-ray staging ratios of RA patients between different WC groups(I-II-III-IV)(x2=0.483,P=0.923).There was no significant difference in Sharp scores between different WC groups(normal:elevated)in RA patients(z=0.708,P=0.479).(13)Comparisons of BMD and OP incidence in different parts of RA patients among different sarcopenia obesity groups.The median BMD of different parts of RA patients among different sarcopenia obesity groups(normal-obesity-sarcopenia-sarcopenia obesity)is shown in Table 16.The results showed that the average BMD of RA patients was significantly different among different sarcopenia obesity groups(P<0.005-0.0001),and BMD was gradually decreasing.The incidence of OP in different parts of RA patients in different sarcopenia obesity groups was significantly different(P<0.0001),and the incidence of OP was higher in sarcopenia and sarcopenia obesity groups.(14)The comparison of hands joint X-ray staging composition ratio and Sharp of RA patients in different sarcopenia obesity groups.The X-ray staging ratio(I-II-III-IV)of RA patients with different sarcopenia obesity groups(normal:obesity:sarcopenia:sarcopenia obesity)was significantly different(28.6%-23.8%-32.1%-15.5%:27.2%-13.6%-35.0%-35.0%-24.3%:16.7%-15.3%-36.1%-31.9%:9.7%-21.5%-34.0%-34.7%;x~2=26.002,P=0.002).Sharp scores of RA patients among different sarcopenia obesity groups showed significant differences[10.00(2.00-47.00):14.00(2.00-71.00):48.00(12.00-111.00):55.00(7.00-130.00),[z=29.240,P<0.0001],and assumed a gradual upward trend.(15)The correlation analysis between BMI,PBF and WC and the disease-related indicators of RA patients.BMI was negatively correlated with ESR,CRP,DAS28,RF,HAQ and Sharp scores of RA patients(P<0.05-0.0001),and positively correlated with BMD of all parts(P<0.0001);PBF was positively correlated with joint function,X-ray staging of both hands and Sharp scores of RA patients(P<0.0.0001).There was a negative linear correlation between WC and the number of tenderness,ESR,CRP and DAS28 in patients with RA(P<0.05-0.0001),and a positive linear correlation between WC and BMD in patients with RA(P<0.05-0.008).(16)Multiple linear Regression correlation analysis.Joint swelling,joint tenderness,VAS and ESR were positively proportional to DAS28 in RA patients(P<0.001-0.0001),while BMI,PBF and WC were not correlated with disease activity in RA patients(P>0.05).(17)Multiple linear Regression correlation analysis of Sharp score of RA patients.The course of disease and PBF were positively correlated with Sharp score of RA patients(P<0.05-0.0001),while BMI was negatively correlated with Sharp score of RA patients(P<0.0001),and other indicators were not correlated with Sharp score of RA patients(P>0.05).(18)Multiple logistic regression analysis of OP in RA patients.Female,advanced age and sarcopenia obesity were a risk factor for RA patients to be hit by OP(P<0.01-0.0001),while BMI was a protective factor for RA patients from OP(P=0.001).conclusion(1)Incidence of different types of obesity in RA patients is different.(2)Increased body fat and sarcopenia might be risk factors for bone and joint injury in RA patients. |
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