Table 2.
Baseline demographic characteristics of the patients
| Rheumatologist's clinical diagnosis of axial SpA and fulfillment of classification criteria | ||||||
|---|---|---|---|---|---|---|
| Yes by clinical diagnosis | No by clinical diagnosis | |||||
| AS(n = 101)a | Nonradiographic axial SpA(n = 157)b | Non–axial SpA(n = 61) | AS(n = 6)a | Nonradiographic axial SpA(n = 72)b | Non–axial SpA(n = 300) | |
| Female, no. (%) | 43 (43) | 84 (54) | 33 (54) | 5 (83) | 43 (60) | 179 (60) |
| Age, mean ± SD years | 41.5 ± 12.4 | 40.6 ± 11.9 | 42.6 ± 11.4 | 49.5 ± 17.1 | 41.8 ± 12.6 | 41.8 ± 12.6 |
| Race, no. (%) | ||||||
| White | 85 (84) | 143 (91) | 55 (90) | 6 (100) | 65 (90) | 265 (88) |
| African American | 11 (11) | 7 (4) | 2 (3) | 0 | 3 (4) | 24 (8) |
| Asian | 2 (2) | 6 (4) | 2 (3) | 0 | 2 (3) | 6 (2) |
| Ethnicity, no. (%) Hispanic orLatino | 11 (10.9) | 19 (12.1) | 9 (14.8) | 1 (16.7) | 6 (8.3) | 39 (13.0) |
| Duration of chronic back pain, mean yearsc | 14.0 | 13.8 | 14.2 | 27.9 | 14.2 | 13.7 |
| Age at onset of chronic back pain, mean ± SD yearsc | 28.1 ± 8.9 | 27.3 ± 9.3 | 28.6 ± 8.5 | 22.2 ± 11.0 | 28.2 ± 9.0 | 28.7 ± 8.9 |
Fulfilled the Assessment of SpondyloArthritis international Society (ASAS) criteria and modified New York criteria for ankylosing spondylitis (AS).
Fulfilled the ASAS criteria but not the modified New York criteria for AS.
Data were available for 100 patients classified as having AS by disease classification criteria who had a clinical diagnosis of axial spondyloarthritis (SpA), 155 patients classified as having nonradiographic axial SpA by disease classification criteria who had a clinical diagnosis of axial SpA, 58 patients classified as having non–axial SpA by disease classification criteria who had a clinical diagnosis of axial SpA, and 298 patients classified as having non–axial SpA by disease classification criteria who did not have a clinical diagnosis of axial SpA.