Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic or lifelong condition involving the joints in the lower portion of the vertebral or spinal column. 

Last Updated: February 21, 2024

While data regarding the number of people with AS are scant, their prevalence is currently estimated to be around 0.01% to 0.5% of the global population. Calculations using figures from relevant literature approximate that more than one and five million patients are stricken with AS in Europe and Asia, respectively.  While such information remains unavailable in the Philippine setting, Filipinos afflicted with the disease have been documented clinically.

The precise cause of AS is yet to be identified, but both a person’s genes and their environment are speculated to play a role in its onset and further worsening. Mutations or variations in more than 60 genes have been associated with AS, the most notable of which are those involving the human leukocyte antigen-B (HLA-B) gene. Like other components of the HLA complex, HLA-B gives instructions for making proteins that help our immune system correctly identify other proteins made by our bodies apart from those generated by invaders (such as viruses, bacteria and parasites). The HLA-B27 variant of this gene is extremely common among those with AS (more than 90% of them) compared to less than 10% of the general population without AS. Nevertheless, having the HLA-B27 variant does not automatically mean that one will eventually develop AS; in fact, roughly 80% of children who inherited HLA-B27 from their parents do not get afflicted with the condition. Furthermore, not all pairs of identical twins with the HLA-B27 variant have AS. Other important risk factors are:

  • Age: AS develops most frequently between late teens and mid-40s.
  • Sex: AS is two to three times more common in males than in females.
  • Family History: People with a relative afflicted with AS are more likely to get it eventually than those with no affected family member.
  • Comorbidities: People with inflammatory bowel disease (IBS, which includes Crohn’s disease and ulcerative colitis), psoriasis, and/or recurring or chronic eye inflammation are more likely to develop AS than those without these conditions.

The early manifestation of AS is the inflammation (arthritis) of the sacroiliac joints that connect the base of the spinal column (sacrum) and upper part of the hip or pelvis (ilium). Later on, the inflammation may spread to joints or tissues in the upper regions of the spine and in other parts of the body. “Ankylosing” means joining together, while “spondylitis” means arthritis of the spine. These terms allude that as the disease progresses over time, the inflammation drives the affected joints and smaller bones to “fuse” and harden together, eventually becoming inseparable piece(s) of larger, immobile bone.

Signs and symptoms include:

  • Lower back pain and stiffness that is more severe at night, early morning and at rest
  • Stooped posture (bended-forward body when sitting or standing which gives relieves back pain) that can worsen and become permanent
  • Pain, swelling and stiffness in other musculoskeletal regions of the body (especially at later stages of the disease)
    • Joints that connect the spine and the ribs, the inflammation of which causing pain and can lead to difficulty in deep breathing
    • Dactylitis (“sausage digits”) or painful swelling of a finger or toe
    • Large joints such as the hips, knees and shoulders, leading to pain and range of motion decline
    • Other areas such as the neck, Achilles tendon, patellar tendon and plantar fascia
  • Numbness or weakness in areas of the body supplied by nerves being “pressed” by the inflamed bones of the spinal column
  • Fatigue and malaise
  • Appetite and weight loss
  • Anemia determined by pallor or blood testing
  • Frequent inflammation of and pain in at least one eye that is unlikely to impair vision if treated right away
  • Skin rashes
  • Recurrent fever and/or gastrointestinal complaints
  • Abnormalities in the heart and/or the aorta

Diagnosis of AS and further assessment of its severity are made by a physician through medical history-taking, physical examination, imaging (such as x-ray or magnetic resonance imaging/MRI) and blood tests. The treatment goals are to relieve pain and maintain functional range of motion in affected joints, correcting or preventing further deformities in posture, and preventing damage in other organs. With regular guidance from physicians and other health professions, the following interventions may be utilized:

  • Regular safe exercise, movement and physical therapy to maintain optimal posture and joint mobility; these are also thought to slow down disease progression and reduce pain severity
  • Eating healthy food with less or no fried, processed, high-fat and high-sugar content which may reduce chronic inflammation (such as the Mediterranean diet)
  • Maintenance of healthy weight to control pressure being placed to affected bones and joints
  • Avoiding or cessation of smoking (which can worsen AS and its symptoms, as well as making breathing more difficult)
  • Painkillers and/or anti-inflammatory medications for immediate or short-term relief of symptoms
    • Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, naproxen, mefenamic acid and celecoxib
    • Other painkillers such as paracetamol or tramadol, which can be used solely for mild pain episodes or together with NSAIDs for worse/poorly-controlled pain
    • Muscle relaxants
  • Steroids directly injected into affected joints or administered as drops in recurrently-inflamed eyes
  • Disease-modifying anti-rheumatic drugs (DMARDs) to directly control AS
    • Methotrexate, sulfasalazine
    • Biologics against and small-molecule inhibitors of tumor necrosis factor (TNF) and interleukin-17 (IL-17) actions in the body
  • Surgery which may involve joint replacement, placement of metal support, and/or removal of thickened/fused bone fragments
  • Participation and fellowship in patient-led and patient advocacy groups such as the Axial Spondylarthritis Association of the Philippines (ASAP)

As the precise genetic and environmental triggers for AS have yet to be identified, evidence-based approaches for preventing the onset of AS are lacking.

Last Updated: February 21, 2024