What is the effect of Ankylosing Spondylitis (AS) on the development of Osteoporosis?

From the Guidelines

Ankylosing spondylitis significantly increases the risk of developing osteoporosis, particularly in the spine and hips, due to chronic inflammation and abnormal bone formation. The expert panel recommends measurement of bone mineral density (BMD) at the spine and hip by use of dual-energy X-ray absorptiometry (DXA) should be performed after axSpA diagnosis 1. Key factors to consider in the management of osteoporosis in ankylosing spondylitis patients include:

• Chronic inflammation affecting bone quality and increasing the risk of fragility fractures 1
• Reduced bone mineral density (BMD) in patients with axSpA, making them more susceptible to vertebral fractures 1
• The need for regular BMD measurements, particularly in patients with low BMD, osteoporosis, or fragility fractures 1
• The importance of considering the use of medications that may impact BMD, such as glucocorticoids 1 Treatment strategies may involve a combination of:
• TNF inhibitors to reduce inflammation and preserve bone density
• Bisphosphonates, such as alendronate or zoledronic acid, to manage osteoporosis
• Ensuring adequate calcium and vitamin D intake, as well as engaging in weight-bearing exercises as tolerated
• Regular monitoring of bone health through DXA scans every 1-2 years 1.

From the Research

Ankylosing Spondylitis and Osteoporosis

• Ankylosing spondylitis (AS) is associated with an increased risk of osteoporosis, with studies showing a higher incidence of osteoporosis in AS patients compared to the general population 2.
• The risk of osteoporosis in AS patients is attributed to various factors, including systemic inflammation, elevated levels of biochemical markers of bone turnover, and proinflammatory cytokines 3.
• Osteoporosis in AS patients can lead to an increased risk of fractures, particularly vertebral fractures, which can have significant consequences on the patient's quality of life 4, 3.

Diagnosis and Assessment of Osteoporosis in AS

• Dual-energy X-ray absorptiometry (DXA) is commonly used to assess bone mineral density (BMD) in AS patients, but its reliability can be limited in patients with advanced disease and new bone formation 3, 5.
• Lateral lumbar DXA and volumetric BMD measurements may be more sensitive in detecting osteoporosis in AS patients, as they are less affected by syndesmophyte formation 5.
• The use of questionnaires, back mobility tests, blood samples, and lateral spine radiographs can also help assess the risk of osteoporosis in AS patients 5.

Treatment and Management of Osteoporosis in AS

• Bisphosphonates are commonly used to treat osteoporosis in AS patients, and studies have shown that they can improve lumbar spine BMD and reduce the risk of vertebral fractures 4, 6.
• The use of tumor necrosis factor-alpha inhibitors (TNFi) may also have a positive effect on BMD in AS patients, although the outcome on reduction in vertebral fractures remains unclear 4, 6.
• Adequate intake of vitamin D and calcium, as well as participation in weight-bearing activities, are also important for maintaining bone health in AS patients 4.