类风湿关节炎患者骨量改变危险因素分析及FRAX的应用价值

目的：了解计算骨折危险性评估工具（fracture risk assessment tool，FRAX）时，使用与不使用骨密度（bone mineral density，BMD）对中国类风湿关节炎（rheumatoid arthritis，RA）患者骨折概率的影响，分析影响骨量的因素。方法：2009年12月至2012年12月于北京大学第一医院门诊及病房首次就诊的年龄大于40岁RA患者200例，双能X线测定腰椎和左髋部BMD，将使用与不使用BMD或T值计算的FRAX骨折概率进行比较，并结合患者的性别、年龄、绝经时间、体重指数、病程以及激素应用等因素进行相关性分析。结果：200例患者平均年龄（59.4±10.2）岁，77.5%为女性。有77例患者接受了双能X线检查，其中BMD正常和异常组分别为10例（13%）和67例（87%），有32例患者发生骨折。两组患者在平均年龄、糖皮质激素使用（用药时间、累积剂量、目前日平均剂量）、FRAX预测主要部位和髋部骨折风险之间差异均有统计学意义。使用与不使用BMD、T值计算的未来10年骨折概率差异无统计学差异。结合T值得出的FRAX预测骨折风险的ROC曲线下面积最大（0.899）。以腰椎及髋部的BMD作为结果变量，对影响患者BMD的因素进行多元回归分析显示：患者的疼痛评分（P=0.02）、既往发生骨折（P=0.003）、糖皮质激素的累积剂量（P=0.008）是引起腰椎骨量异常的危险因素，患者的年龄（P<0.001）、已绝经（P=0.05）、既往发生骨折（P=0.003）、体重指数（P=0.03）是引起左髋部骨量异常的危险因素。结论：RA患者骨折发生比例较高，主要部位和髋部骨折风险均增加，结合股骨颈BMD或T值计算FRAX能更有效地预测骨折概率。

Risk factors for bone mineral density changes in patients with rheumatoid arthritis and fracture risk assessment

Objective:To verify the fracture risk assessment tool ( FRAX) to estimate the probability of osteoporotic fracture in patients with rheumatoid arthritis ( RA ) with or without bone mineral density (BMD), and identify associated risk factors of osteoporosis .Methods: In the study, 200 patients with rheumatoid arthritis aged more than 40 years in Peking University First Hospital from Dec .2009 to Dec. 2012 were recruited.Clinical information was obtained from a questionnaire of their case history and medical records.FRAX tool was administered.Their lumber spine and left femoral BMD were determined by dual energy X ray absorptiometry.The gender, age, disease duration, menopause status, body mass index ( BMI) and accumulative dose of glucocorticoid were obtained in retrospect .Correlation analysis was conducted between the BMD and clinical information .Results:The study population ( female, 77.5%) had a mean age of 59.4 years, in which 10 (13%) patients showed a normal BMD, 67 (87%) were osteopenia or osteoporosis , while 32 patients (16%) had fragile fracture.Compared with the patients with normal BMD, the subjects with low BMD had significantly older age , longer period for corticoids usage , higher day dose and accumulated dose of corticoids .The 10-year fracture risk of sustai-ning major osteoporotic fractures and hip fracture was higher .No significant difference was observed be-tween the 10-year fracture risks calculated with BMD and without BMD .The values of the different area under the receiver operating characteristic ( ROC) curve ( AUC) for major and hip fractures calculated in three ways:without BMD, with the femoral neck BMD, and with T-score.The best result was for FRAX tool for hip fracture with the T-score ( AUC 0 .899 ) .A stepwise multivariate linear regression model was constructed to explore the relationship between the different clinical factors studied and a low BMD . Three statistically significant variables for lumber BMD were pain on visual assessment scale ( VAS ) (P=0.02), fracture history (P=0.003) and a higher steroid accumulated dose (P=0.008).Three statistically significant variables for left hip BMD were age (P<0.001), fracture history (P=0.05) and lower BMI ( P=0.03) .Conclusion:Low BMD is a common complication in RA patients .Risk factors for major fracture and hip fracture are increased .There is a positive correlation between FRAX calculated with and without BMD or T score .FRAX with the femoral neck T score or BMD presents a discriminatory capacity better than FRAX without BMD , according to the AUC ROC .