What is the clinical presentation of undifferentiated spondyloarthropathy (USpA)?

Updated: Feb 02, 2021
  • Author: Lawrence H Brent, MD; Chief Editor: Herbert S Diamond, MD  more...
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USpA has features consistent with the spondyloarthropathies, but affected patients do not fulfill criteria for any specific spondyloarthropathy. [72, 82]

USpA may represent an early phase or incomplete form of AS or another spondyloarthropathy. In fact, several studies of USpA included many patients who probably should have been diagnosed with AS, ReA, or IBD-associated spondyloarthropathy, which made the clinical description very ambiguous. However, subsequent data suggest that these patients may represent a distinct disease entity on the basis of demographic and clinical criteria.

Although no specific criteria are identified, using modified Amor criteria can be helpful in confirming a clinical diagnosis of USpA (see Table 3 below). [59, 83, 7]

Table 3. Diagnostic Criteria for Undifferentiated Spondyloarthropathy Using Modified Amor Criteria (Open Table in a new window)

Inclusion Criteria

Exclusion Criteria

Inflammatory back pain

1 point

Diagnosis of specific spondyloarthropathy

Unilateral buttock pain

1 point

Sacroiliitis on radiograph = grade 2

Alternating buttock pain

2 points

Precipitating genitourinary/gastrointestinal infection


2 points


Peripheral arthritis

2 points

Keratoderma blennorrhagicum

Dactylitis (sausage digit)

2 points

Inflammatory bowel disease (Crohn disease or ulcerative colitis)

Acute anterior uveitis

2 points

Positive rheumatoid factor

HLA-B27 positive or family history of spondyloarthropathy

2 points

Positive antinuclear antibody, titer > 1:80

Good response to nonsteroidal anti-inflammatory drugs

2 points


Diagnosis of spondyloarthropathy with 6 or more points

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