Magrey Marina N, Lewis Steven, Asim Khan Muhammad
Department of Medicine, MetroHealth Medical Center, School of Medicine, Case Western Reserve University, 2500 MetroHealth Dr, Cleveland, OH.
Center for Health Care Research and Policy, Case Western Reserve University at Metrohealth Medical Center, Cleveland, OH.
Semin Arthritis Rheum. 2016 Aug;46(1):88-94. doi: 10.1016/j.semarthrit.2016.03.003. Epub 2016 Mar 9.
Conventional DXA imaging of spine and hip to measure bone mineral density (BMD) has limitations in patients with ankylosing spondylitis (AS). We investigated the correlation of hip and spine BMD measurements in patients with AS to determine if hip DXA will prove clinically useful while avoiding the confounding effect of spinal disease. Also, we studied risk factors for osteoporosis (OP) and osteopenia in AS.
We randomly identified patients from our validated AS registry ≥18 years of age who met the Modified New York Classification criteria for AS. BMD was measured and interpreted using ISCD 2007 guidelines and diagnosis of OP was based on WHO criteria. ESR, CRP, urinary N-telopeptide, and 25-hydroxy vitamin D were also measured. Correlation between the BMD (total hip and/or femoral neck) and lumbar spine was calculated. Statistical comparisons between the 2 sites, lumbar spine (AP) and hip (total hip and or femoral neck) were made using Bowker's test for symmetry and kappa statistics. Chi-square and odds ratio using logistic regression were used to assess the association of the purported risk factors for OP in these patients.
Frequency of OP among AS patients ≥50 years of age was 23%, and that of osteopenia was 41%. Among patients <50 years of age, the frequency of low bone mass for expected age (Z-score ≤-2.0) was 14.7%. There was moderate correlation (ρ = 0.59) and a fair agreement (κ = 0.26; 95% CI: 0.10-0.42) between the lowest T-values of hip and lumbar spine (AP view). OP was significantly associated with elevated CRP level [OR = 4.2 (95% CI: 1.13-15.9), p < 0.03] and African American race [OR = 7.2 (95% CI: 1.18-44.99), p < 0.03].
Our results demonstrated a moderate correlation and fair agreement between the T-scores of hip and the lumbar spine (AP view) in patients with AS, suggesting that DXA of the hip and the lumbar spine (AP view) may both be useful for OP and osteopenia screening in patients with AS without fused spines. We confirm the previous reports of an association of elevated CRP level with an increased risk of OP in patients with AS, but this is the first study to demonstrate that African American patients with AS may be at a higher risk of developing OP compared to Caucasians.
传统的脊柱和髋部双能X线吸收法（DXA）成像用于测量骨密度（BMD），在强直性脊柱炎（AS）患者中存在局限性。我们研究了AS患者髋部和脊柱BMD测量值之间的相关性，以确定髋部DXA在避免脊柱疾病混杂效应的同时是否具有临床实用性。此外，我们还研究了AS患者骨质疏松症（OP）和骨质减少的危险因素。
我们从经过验证的AS登记处随机选取年龄≥18岁且符合AS改良纽约分类标准的患者。使用国际临床骨密度学会（ISCD）2007年指南测量并解读BMD，OP的诊断基于世界卫生组织（WHO）标准。还测量了红细胞沉降率（ESR）、C反应蛋白（CRP）、尿N-端肽和25-羟基维生素D。计算BMD（全髋和/或股骨颈）与腰椎之间的相关性。使用Bowker对称性检验和kappa统计量对腰椎（前后位）和髋部（全髋和/或股骨颈）这两个部位进行统计学比较。使用卡方检验和逻辑回归的优势比来评估这些患者中OP的假定危险因素之间的关联。
年龄≥50岁的AS患者中OP的发生率为23%，骨质减少的发生率为41%。在年龄<50岁的患者中，预期年龄低骨量（Z评分≤ -2.0）的发生率为14.7%。髋部和腰椎（前后位视图）的最低T值之间存在中度相关性（ρ = 0.59）和一般一致性（κ = 0.26；95%可信区间：0.10 - 0.42）。OP与CRP水平升高[优势比 = 4.2（95%可信区间：1.13 - 15.9），p < 0.03]和非裔美国人种族[优势比 = 7.2（95%可信区间：1.18 - 44.99），p < 0.03]显著相关。
我们的结果表明，AS患者髋部和腰椎（前后位视图）的T评分之间存在中度相关性和一般一致性，这表明髋部和腰椎（前后位视图）的DXA可能都有助于对未发生脊柱融合的AS患者进行OP和骨质减少的筛查。我们证实了先前关于AS患者CRP水平升高与OP风险增加相关的报道，但这是第一项表明与白种人相比，AS非裔美国患者发生OP的风险可能更高的研究。
