Department of Rheumatology and Inflammation Research, Sahlgrenska Academy at University of Gothenburg, Guldhedsgatan 10A, S-413 46 Göteborg, Sweden.
Arthritis Res Ther. 2012 May 8;14(3):R108. doi: 10.1186/ar3833.
Osteoporosis can be a complication of ankylosing spondylitis (AS), but diagnosing spinal osteoporosis can be difficult since pathologic new bone formation interferes with the assessment of the bone mineral density (BMD). The aims of the current study were to investigate prevalence and risk factors for reduced BMD in a Swedish cohort of AS patients, and to examine how progressive ankylosis influences BMD with the use of dual-energy x-ray absorptiometry (DXA) of the lumbar spine in different projections.
Methods of assessment were questionnaires, back mobility tests, blood samples, lateral spine radiographs for syndesmophyte grading (mSASSS), DXA of the hip, radius and lumbar spine in anteroposterior (AP) and lateral projections with estimation of volumetric BMD (vBMD).
AS patients (modified New York criteria), 87 women and 117 men, mean age 50 ± 13 years and disease duration 15 ± 11 years were included. According to World Health Organization (WHO) criteria 21% osteoporosis and 44% osteopenia was diagnosed in patients > = 50 years. Under age 50 BMD below expected range for age was found in 5%. Interestingly lateral lumbar DXA showed significantly lower BMD and revealed significantly more cases with osteoporosis as compared with AP DXA. Lumbar vBMD was not different between sexes, but women had significantly more lumbar osteoporosis measured with AP DXA (P < 0.001). Men had significantly higher mSASSS (P < 0.001). Low BMD was associated with high age, disease duration, mSASSS, Bath Ankylosing Spondylitis Metrology Index (BASMI), inflammatory parameters and low body mass index (BMI). Increasing mSASSS correlated significantly with decreasing lateral and volumetric lumbar BMD, while AP lumbar BMD showed tendency to increase.
Osteoporosis and osteopenia is common in AS and associated with high disease burden. Lateral and volumetric lumbar DXA are more sensitive than AP DXA in detecting osteoporosis and are less affected by syndesmophyte formation.
骨质疏松症可能是强直性脊柱炎（AS）的并发症，但是由于病理性新骨形成会干扰骨密度（BMD）的评估，因此诊断脊柱骨质疏松症可能具有挑战性。本研究的目的是调查瑞典 AS 患者队列中 BMD 降低的患病率和危险因素，并使用腰椎双能 X 射线吸收法（DXA）在不同投影中检查进行性强直如何影响 BMD。
评估方法包括问卷调查、腰背活动度测试、血液样本、脊柱侧位片用于测量骨融合（mSASSS）、髋关节、桡骨和腰椎的 DXA 前后位（AP）和侧位投影，同时估计体积 BMD（vBMD）。
纳入了符合改良纽约标准的 AS 患者（87 名女性和 117 名男性），平均年龄 50 ± 13 岁，病程 15 ± 11 年。根据世界卫生组织（WHO）标准，> = 50 岁的患者诊断出 21%的骨质疏松症和 44%的骨量减少。50 岁以下的患者中，有 5%的 BMD 低于年龄预期范围。有趣的是，与 AP DXA 相比，侧位腰椎 DXA 显示出明显较低的 BMD，并且发现了更多的骨质疏松症病例。腰椎 vBMD 在性别之间没有差异，但女性在 AP DXA 上腰椎骨质疏松症的发生率明显更高（P < 0.001）。男性的 mSASSS 明显更高（P < 0.001）。低 BMD 与高年龄、病程、mSASSS、巴斯强直性脊柱炎计量指数（BASMI）、炎症参数和低体重指数（BMI）有关。mSASSS 的增加与侧位和体积腰椎 BMD 的降低显著相关，而 AP 腰椎 BMD 则有增加的趋势。
AS 患者中常见骨质疏松症和骨量减少，与高疾病负担有关。与 AP DXA 相比，侧位和体积腰椎 DXA 更敏感地检测骨质疏松症，并且受骨融合形成的影响较小。
