Clinical Research Of Sarcopenia, Vitamin D Deficiency And Falls In Rheumatoid Arthritis With Spinal Osteoporotic Fractures

Background Rheumatoid arthritis(RA)is an autoimmune disease which is characterized by chronic synovitis, and the latter could lead to bone and joint damage/which represents as local destruction of joints and general osteoporosis(OP). OP is a systemic bone disease, while bone loss, structural deterioration of bone tissue, leading to bone fragility and increased susceptibility to osteoporotic fractures(OPF) are the main features of OP. OP is the main reason of losing capacity for physical labor and disability, and OP will cause RA patients suffering great economic and life stress,. The vertebral column is one of the most commonly involved fracture sites. At present, there are little literatures about spinal OPF in patients with RA domestic and verseas, but most of studies have pointed out that the reduction of serum 25 hydroxy vitamin D(25(OH) D) can lead to falls and the occurrence of OP. Sarcopenia originally meant lacking of muscle. In 1989, Irwin described it as decline of muscle and strength in old people for the first time. In 2010, sarcopenia is defined as a functional decline of skeletal muscle mass and strength in the elderly by European working group on sarcopenia in older people(EWGSOP). The key point of sarcopenia is decrease of skeletal muscle mass, or muscle strength declining, or lowering of skeletal muscle function. Recent studies suggest that the occurrence of OP is related with sarcopenia. However, studies on OPF in patients with RA are rare, and the contribution of sarcopenia to RA patients with OPF is unclear. The aim of our study is to investigate the prevalence of OPF at vertebral column in RA and to explore associations between OPF with vitamin D(Vit D) deficiency, sarcopenia and falls by detecting anteroposterior and lateral X-rays examination of vertebral column(T5-L5), bone mineral density(BMD) and determining the level of serum 25(OH) D and the quality of skeletal muscle at different body parts for every patient, which will provide theoretical basis for clinical intervention of OPF in RA.ObjectiveTo investigate the prevalence of serum 25(OH) D deficiency, sarcopenia and falls in patients with rheumatoid arthritis(RA), to explore the effect of above factors on osteoporotic fracture(OPF). Methods A total of nine hundred and thirty-six patients with RA who fulfilled the 1987 ACR classification criteria or 2009 classification criteria of RA by ACR from department of rheumatology & immunology, the first affiliated hospital of Anhui medical university and 158 age, gender-matched normal subjects(as controls) from Jan. 2013 to Oct. 2015 were recruited. Anteroposterior and lateral X-rays scanning of vertebral column(T5-L5) were conducted for every individual, and semi-quantity method were used as the standard for determining vertebral OPF. Bone mineral density(BMD) of hip and all the vertebrae of lumbar in 648 RA patients and all the controls were detected by the DEXA. Skeletal muscle mass and the balance ability of 267 cases and 156 controls were measured by the method of biological electrical impedance and Berg balance scale. Serum levels of 25-hydroxy vitamin D(25(OH)D) were examined by electrochemiluminescence in 234 RA patients and 68 normal subjects. Meanwhile, clinical and laboratory index of patients including usage of glucocorticoid(GC) and fall in 296 RA were recorded in details.Results 1. The percentage of OP in RA was 37.8%(245/648), higher than that in control group(13.9%, 22/158)(x2=32.712,P<0.001). The prevalence of vertebral OPF in RA was 15.1%(141/936), which was 4.0 times the prevalence of control group(6/158, 3.8%)(x2=18.658,P<0.0001), while T12 and L1 was the most common involved fracture site. The total prevalence of sarcopenia in RA which was determined by skeletal muscle mass in limbs was 55.8%(149/267), it was apparently higher than that in control group(9.0%, 14/156)(x2=91.176,P<0.0001). The occurrence rate of falls in RA was 20.3% during the last year(60/296). 2. Compared to control group, RA patients had lower serum 25(OH)D levels [(22.40±6.26)ng/ml,(13.41±9.71)ng/ml, t=9.063, P<0.0001]. Of 234 RA with valid serum 25(OH) D levels, 36 cases which accounted for 15.5% were classified as Vitamin D insufficiency. Serum 25(OH)D levels in 189 cases which accounted for 80.8% was categorized as Vitamin D deficiency. In control group, the rate of Vitamin D insufficiency and Vitamin D deficiency were 52.9%(36/68) and 36.8%(25/68). The incidence of Vitamin D deficiency between the two groups was statistically different [80.8%(189/234) vs 36.8%(25/68), x2 = 49.412, P<0.0001]. 3. Compared to RA without OPF, patients with OPF had lower serum 25(OH)D levels [(17.16±10.90)ng/ml vs(12.28±5.67)ng/ml, t=2.600, P=0.01]. The percentage of Vitamin D deficiency in RA with OPF group was 89.2%(33/37), which was higher than that in RA without OPF group(69.8%, 74/106, x2=5.467, P=0.019). Patients with falls had lower serum 25(OH)D levels, compared with Patients without falls [(11.66±6.24) ng/ml,(17.23±7.14)ng/ml, t=3.615, P<0.001]. Patients with falls also had higher incidence of Vitamin D deficiency(88.5%, 23/26)than that in RA without falls(68.8%, 66/96, x2=4.028, P=0.045). 4. The prevalence of falls during the last year in RA with vertebral OPF was 39.2%(20/51), which was higher than that in RA without OPF(15.7%, 22/140)(x2=12.036, P=0.001). Incidence of Berg balance scale score <40 in patients with OPF(68.8%, 33/48) was higher than that in group without OPF(29.7%, 35/118)(x2=21.558, P<0.001). 5. The total prevalence of OPF in RA patients with glucocorticoid(GC) was 22.7%(102/449), which was apparently higher than that in group without GC(12.0%, 41/343)(x2=15.227, P<0.001). The percentage of sarcopenia in RA patients taking GC was 62.1%(90/145), higher than that in group without taking GC(47.9%, 58/121). Patients with taking GC also had higher incidence of falls than that in patients without taking GC(28.9%, 48/166 vs 9.4%, 12/128, x2=16.989, P<0.001). 6. RA patients with sarcopenia had lower Berg balance scale score than that in RA without sarcopenia [37.27±13.93 vs 43.36±12.55, t=3.524, P=0.001]. Incidence of Berg balance scale score <40 in patients with sarcopenia(50.8%, 65/128) was higher than that in group without sarcopenia(29.9%, 32/107)(x2=10.477, P=0.001). The prevalence of falls during the last year in RA with sarcopenia was 26.1%(37/142), which was higher than that in RA without sarcopenia(12.3%, 14/114)(x2=7.522, P=0.006). 7. Compared to RA without OPF, general and every part of extremities skeletal muscle mass and Berg balance scale score were significantly decreased in RA with OPF(P<0.05). Patients with Berg balance scale score <40 also had general and every part of extremities skeletal muscle mass than that in patients with Berg balance scale score≥40(P<0.05). 8. Linear correlation analysis found that Berg balance scale score positively correlated with BMD at femoral and lumbar region in RA(P<0.05). Serum 25(OH) D levels positively correlated with Berg balance scale score in RA(P=0.022). Meanwhile, skeletal muscle mass positively correlated with Berg balance scale score, BMD at site of hip and lumbar vertebra(P<0.05). 9. Defined sex(1=male, 2= female), age, fall(0=no, 1=yes), Berg balance scale score, duration of disease, serum 25(OH) D level, HAQ, usage of GC(0=no, 1=yes), occurrence of OP at femoral and lumbar region(0=without OP, 1=OP) as independent variable, and sarcopenia as the dependent variable, logistic regression analysis(LR Backward) found that sex(OR=10.833, P<0.001, 95% CI:3.154-37.207), HAQ(OR=2.535, P=0.001, 95% CI:1.463-4.392) and occurrence of OP at femur(OR=5.376, P=0.015, 95% CI:1.391-20.777) were the risk factors for sarcopenia in RA patients. Defined sex(1=male, 2=female), age, fall(0=no, 1=yes), Berg balance scale score, duration of disease, HAQ, usage of GC(0=no, 1=yes), skeletal muscle mass index(SMI), occurrence of OP at femoral and lumbar region(0=without OP, 1=OP) as independent variable, and OPF(0=without OPF, 1=OPF) as dependent variable, logistic regression analysis(LR Backward) found that age(OR=1.075, P=0.002, 95% CI:1.028-1.124) was the risk factors for OPF in RA patients, while 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 the protective factors.Conclusion 1. Incidences of OP and OPF in patients with RA are higher than that in normal subjects. Serum 25(OH) D levels is generally low in RA patients, and so are decreased balanced capacity, high incidences of falls and sarcopenia. 2. Decreased serum 25(OH) D levels deficiency, skeletal muscle mass and balance capacity and falls in RA are closely correlated with each others, they are all related with spinal OPF in RA.