Clinical Trial of Osteoporosis in Ankylosing Spondylitis
Condition: Ankylosing Spondylitis
MeSH terms: Spondylitis; Osteoporosis; Spondylarthritis; Spondylitis, Ankylosing
Study type: Observational

Summary: 
      This is an observational study aiming to study the prevalence and risk factors for
      osteoporosis and vertebral fractures in patients with ankylosing spondylitis attending three
      Rheumatology clinics in Western Sweden.
    

Detailed description: 
      Background Ankylosing spondylitis (AS) is a common inflammatory rheumatic disease with a
      prevalence of 0.5-1.0%. Men are more commonly affected by the disease as compared to women,
      ratio 2.6-4:1. Pain in the back is a frequent symptom of debut. This pain is often associated
      with sacroilitis. In later stages also the lumbar, thoracic and cervical spine are hit by the
      disease. Peripheral joints, eyes, heart, lungs and urinary tract may also be influenced.

      Osteoporosis in AS In AS the risk of osteoporosis is increased. However, this field has not
      yet been significantly studied probably due to several reasons such as the predominance of
      men with the disease and men are more seldom investigated for osteoporosis compared to women.
      When AS progresses syndesmophytes of the spine are developed which makes it difficult to
      assess bone mineral density (BMD) correctly with the conventional method, dual energy x-ray
      absorptiometry (DXA). Fractures in the spine are easy to foreseen since the pain of the
      patient might be misjudged to be related to increased disease activity. Fractures are also
      overlooked in radiographs in AS. AS is associated with both increased bone formation and
      increased bone resorption. The bone remodeling process in the spine renders the spine less
      flexible and stiffer and as a consequence also a quite small trauma may result in a fracture.
      These fractures are often instable risking injuring the spinal cord and nerves.

      Aims of the study

        -  To investigate the prevalence of osteoporosis and osteoporosis related fractures in
           patients with AS in Western Sweden.

        -  To identify risk factors for osteoporosis and osteoporosis related fractures in AS.

        -  To study how fractures in the spine may influence the pain in the back, the flexibility
           of the spine and the posture of the patients.

        -  To study to which extent the patients with AS are investigated and treated for
           osteoporosis.

        -  To investigate which method is most reliable for measuring BMD in AS.

      Design and methods This is an observational study consisting of questionnaires, examination
      of the patients, blood tests, measures of BMD with different techniques, DXA, both
      frontal-dorsal and lateral projections, Quantitative Computed Tomography (QCT) and Xtreme CT.
      Patients with AS from three rheumatology clinics in western Sweden with definite AS will be
      invited to participate. It is estimated that about 250 patients will be included in the
      trial. All patients gave informed written consent according to the Declaration of Helsinki.
      The study has been approved by the Regional Ethics Committee.
    

Observational model: Case-Crossover
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        Patients with definitive ankylosing spondylitis attending three rheumatology clinics in
        Western Sweden.
      
Biospecimen description: 
      Serum
    
Keywords: Osteoporosis; Fractures; Bone Mineral Density; Quantitative Computed Tomography