Table 2.
Demographic characteristics of nonradiographic axial spondyloarthritis, ankylosing spondylitis, and other inflammatory back pain patients
| Total (N = 914) | nr-axSpA (n = 266) | AS (n = 491) | Other IBP (n = 157) | p Value | |
|---|---|---|---|---|---|
| Sex | <0.001 | ||||
| Male, n (%) | 588 (64.33 %) | 169 (63.53 %) | 350 (71.28 %) | 69 (43.95 %) | |
| 95 % CI | (61.22–67.44) | (57.74–69.33) | (67.27–75.29) | (36.17–51.73) | |
| Female, n (%) | 326 (35.67 %) | 97 (36.47 %) | 141 (28.72 %) | 88 (56.05 %) | |
| 95 % CI | (32.56–38.78) | (30.67–42.26) | (24.71–32.73) | (48.27–63.83) | |
| Sex | <0.001 | ||||
| Male, n (row %) | 588 (100.00 %) | 169 (28.75 %) | 350 (59.52 %) | 69 (11.73 %) | |
| 95 % CI | (25.08–32.41) | (55.54–63.50) | (9.13–14.34) | ||
| Female, n (row %) | 326 (100.00 %) | 97 (29.75 %) | 141 (43.25 %) | 88 (26.99 %) | |
| 95 % CI | (24.78–34.73) | (37.86–48.64) | (22.17–31.82) | ||
| Age, years, mean ± SD | 38.68 ± 12.02 | 34.75 ± 10.03 | 39.03 ± 11.38 | 44.26 ± 14.48 | <0.001 |
| Race/ethnicity | <0.001 | ||||
| White, n (%) | 596 (65.21 %) | 148 (55.64 %) | 335 (68.23 %) | 113 (71.97 %) | |
| 95 % CI | (62.11–68.30) | (49.66–61.62) | (64.10–72.35) | (64.94–79.01) | |
| Asian, n (%) | 116 (12.69 %) | 55 (20.68 %) | 55 (11.20 %) | 6 (3.82 %) | |
| 95 % CI | (10.53–14.85) | (15.80–25.55) | (8.41–14.00) | (0.82–6.83) | |
| Black, n (%) | 12 (1.31 %) | 2 (0.75 %) | 2 (0.41 %) | 8 (5.10 %) | |
| 95 % CI | (0.57–2.05) | (0.00–1.79) | (0.00–0.97) | (1.65–8.54) | |
| Unknown, n (%) | 190 (20.79 %) | 61 (22.93 %) | 99 (20.16 %) | 30 (19.11 %) | |
| 95 % CI | (18.15–23.42) | (17.87–27.99) | (16.61–23.72) | (12.95–25.27) | |
| BMI category | 0.024 | ||||
| Underweight, n (%) | 55 (6.02 %) | 12 (4.51 %) | 38 (7.74 %) | 5 (3.18 %) | |
| 95 % CI | (4.47–7.56) | (2.01–7.01) | (5.37–10.11) | (0.43–5.94) | |
| Normal weight, n (%) | 455 (49.78 %) | 150 (56.39 %) | 236 (48.07 %) | 69 (43.95 %) | |
| 95 % CI | (46.53–53.03) | (50.42–62.36) | (43.64–52.49) | (36.17–51.73) | |
| Overweight, n (%) | 279 (30.53 %) | 78 (29.32 %) | 146 (29.74 %) | 55 (35.03 %) | |
| 95 % CI | (27.53–33.52) | (23.84–34.8) | (25.68–33.79) | (27.56–42.51) | |
| Obese, n (%) | 121 (13.24 %) | 24 (9.02 %) | 70 (14.26 %) | 27 (17.20 %) | |
| 95 % CI | (11.04–15.44) | (5.57–12.47) | (11.16–17.36) | (11.28–23.11) | |
| Unknown, n (%) | 4 (0.44 %) | 2 (0.75 %) | 1 (0.20 %) | 1 (0.64 %) | |
| 95 % CI | (0.01–0.87) | (0.00–1.79) | (0.00–0.60) | (0.00–1.88) | |
| Years since CLBP presentation | <0.001 | ||||
| Number of patients | 808 | 232 | 435 | 141 | |
| Mean ± SD, years | 9.09 ± 9.07 | 6.32 ± 7.61 | 10.91 ± 9.37 | 8.05 ± 9.10 | |
| Age of IBP onset | <0.001 | ||||
| Number of patients | 908 | 264 | 488 | 156 | |
| Mean ± SD, years | 28.8 ± 9.7 | 27.8 ± 7.3 | 27.0 ± 7.7 | 36.2 ± 14.2 |
Abbreviations: AS ankylosing spondylitis, BMI body mass index, CLBP chronic low back pain, CRF case report form, IBP inflammatory back pain, nr-axSpA nonradiographic axial spondyloarthritis
Broad race categories (white vs. black vs. Asian vs. unknown) were created on the basis of physician-reported patient ethnicity: white = Indian, Indo-Aryan, Dravidian, Bengali, Arab, Iranian, white, Jewish, Azeri, Mestizo, Amerindian, Berber; black = black, mulatto, mulato, zambo, black African, colored; Asian = Han Chinese, non-Han Chinese, Taiwanese, Chinese, aborigine, Malay, indigenous, mongoloid, Asian; unknown = other or missing
The p values represent the omnibus statistical comparison of percentages (or means) across IBP groups based on the chi-square (or F-test) values
“Other IBP” refers to patients who did not meet the Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis