Table 2.

Amor and ESSG case definitions for SpA^*

	Score	NHANES
Amor SpA criteria elements†
Nocturnal spinal pain or morning stiffness	1	Yes
Buttock/alternating buttock pain	1 or 2‡	Yes
Heel pain/enthesiopathy	2	Yes
Acute diarrhea at or prior to SpA onset	1	No
Radiologic sacroiliitis	3	No
HLA–B27 positive or family/genetic background	2	No
Psoriasis, balanitis, inflammatory bowel disease	2	Yes§
Iritis	2	Yes
Positive response to NSAIDs	2	Yes
Asymmetric oligoarthritis	2	No
Dactylitis	2	No
ESSG SpA criteria elements
Inflammatory spinal pain		Yes
Alternating buttock pain		Yes
Enthesopathy		Yes
Urethritis, cervicitis, diarrhea		No
Radiologic sacroiliitis		No
Positive family history		No
Psoriasis		Yes
Inflammatory bowel disease		Yes

^*Probable SpA is an Amor criteria score of 5 and definite SpA is a score of 6. The European Spondylarthropathy Study Group (ESSG) criteria for SpA are a history of inflammatory spinal pain plus 1 additional ESSG SpA criteria element. SpA = spondylarthritis; NHANES = National Health and Nutrition Examination Survey; NSAIDs = nonsteroidal antiinflammatory drugs.

^† Lumbar or dorsal pain during the night, or morning stiffness of lumbar or dorsal spine.

^‡ Buttock pain = 1; history of alternating buttock pain = 2.

^§ The NHANES did not collect a history of balanitis.