Influence of Disease Activity and Chronicity on Ankylosing Spondylitis Bone Mass Loss

Abstract

We investigated 30 consecutive Brazilian patients with definite ankylosing spondylitis (AS) fulfilling the New York and the European spondyloarthropathy study group classification criteria. The mean age at study was 37 years old and the mean disease duration was 17 years. Bone densitometry employed the dual-energy X-ray absorptiometry (DEXA) technique, using a Hologic QDR-1000/W densitometer. Axial bone mineral density (BMD) was measured in the lumbar spine (L1-L4) and appendicular BMD was measured in the total proximal femur and sub-regions (neck, greater trochanter, intertrochanter and Ward's triangle). Based on World Health Organisation criteria, the lumbar spine showed osteopenia or osteoporosis in 50% of the patients, while 86% had osteopenia or osteoporosis in the total proximal femur. When compared with the normal population, the patients showed a significant BMD decrease in the lumbar spine and total proximal femur with sub-regions, except for the femoral neck. A comparison of BMD between patients with active and inactive disease did not reveal a significant effect of clinical disease activity on the lumbar spine and total proximal femur with sub-regions, except for Ward's triangle. Concerning disease chronicity, there were significant positive correlations between disease duration and lumbar spine, total proximal femur, greater trochanter and intertrochanteric regional BMD. This false increase in lumbar spine BMD found mostly in patients with long standing AS was due to the presence of paravertebral calcification and ossification. We conclude that the bone mass loss in AS is better evaluated in the proximal femur, because of the greater sensitivity of bone densitometry in this region, which is almost free of artefacts.

The pathogenesis of ankylosing spondylitis

“…Other causes of osteoporosis beyond the inflammatory osteoclast activation in this population include corticosteroid use, immobility, and hormonal imbalance. 85 Appel and coworkers 3 have established a correlation of histopathological features and magnetic resonance imaging evaluations in 8 patients with AS. The chosen sequence was T2-weighted images with fat saturation in which water appears to have a high intensity.…”

Bone Mineral Density Changes in Patients with Spondyloarthropathies

“…On the contrary, E. S. Meirelles and colleagues have found no correlation between disease activity rated by the rheumatologist and BMD changes (Meirelles et al, 1999). K. Capaci and colleagues has proved that disease activity rated by physician on the basis of radiological signs of vertebral and hip destruction extent has no influence on the bone mass of AS patients (Capaci et al, 2003).…”

“…R. Will and colleagues have not found significant difference in the average lumbar vertebral BMD between patients suffering from AS longer than 10 years and the control group . E. S. Meirelles and colleagues observed positive correlation between disease duration and changes of proximal femoral and lumbar vertebral BMD (Meirelles et al, 1999). Until now only one study that quantifies the magnitude of osteoporosis in population of early SpA patients is available (Van der Weijden et al, 2011).…”

Relationship Between Bone Mineral Density and Disease Activity in Patients with Ankylosing Spondylitis

“…Nevertheless, lateral lumbar DEXA may be more suitable for serial BMD measurements because it has lower radiation dose than QCT. A significant positive correlation between disease duration and lumbar spine BMD has been reported (4,23,24,28,29). This could be due to the presence of syndesmophytes in patients with chronic disease.…”

“…However, we did not found a correlation between LSS and femoral neck BMD. Because of this, femoral neck BMD measurement may be more reliable than lumbar spine BMD in advanced AS (15,(23)(24)(25). Previous studies have shown that vertebral fracture risk is related to low femoral neck BMD, but not with lumbar spine BMD (4,18,22).…”