Peripheral spondyloarthritis

HLA-B*27 gene/antigen

Present in 8% of the population. In 90% of cases of AS.  Present in 50% of reactive arthritis. Associated with other disease but only present in a minority of patients with psoriatic arthritis, Crohn's arthritis or uveitis. 

Diagnosis

The entry step is that the patient should have, at the time of being seen, at least one of the following three findings:

• Arthritis
• Enthesitis (spontaneous pain or tenderness at any enthesis)
• Dactylitis

If the patient satisfies the entry criteria, the patient should show (or have had in the past) at least one of the features of SpA in Group A (below) or at least two of the features of SpA in group B (below):

• Group A SpA features:
  • Uveitis – Confirmed by an ophthalmologist
  • Psoriasis – Diagnosed by a clinician
  • Crohn disease or ulcerative colitis – Diagnosed by a clinician
  • Preceding infection – Urethritis/cervicitis or diarrhea within one month prior to onset of arthritis/enthesitis/dactylitis
  • HLA-B27
  • Sacroiliitis on imaging
• Group B SpA features:
  • Arthritis – Diagnosed by a clinician
  • Enthesitis – Diagnosed by a clinician
  • Dactylitis – Diagnosed by a clinician
  • Inflammatory back pain in the past
  • Family history of SpA – Presence in first- or second-degree relatives of SpA or acute uveitis

Other SpA classification criteria — Research prior to the 2009 and 2011 publication of the ASAS criteria usually classified patients using either the ESSG criteria, the Amor criteria, or the modified New York Criteria for AS. These criteria sets differ somewhat from each other and from the ASAS classification criteria. The ESSG and Amor criteria cover the whole spectrum of SpA and include a broader range of manifestations of SpA compared with the modified New York criteria. However, unlike the ASAS classification criteria, these criteria do not differentiate axial from peripheral disease, a distinction that may be important for providing optimal care and for testing treatment strategies, and MRI findings are not taken into consideration. Because certain medications have been approved by the US Food and Drug Administration (FDA) for AS alone, the Modified New York criteria for AS still play a role in decision making for some medications. [2]

Treatment

• Adalimumab (Humira;Amjevita;Hyrimoz