Table 1.
Baseline characteristics of 994 participants in the longitudinal analysis cohort
| All participants (n = 994) | axSpA without comorbidities (n = 671) | axSpA with ≥1 comorbidity (n = 323) | P-value | ||
|---|---|---|---|---|---|
| Mean age, years | 44.7 (13.4) | 43.0 (12.7) | 48.3 (14.2) | <0.001 | |
| Males | 679 (68%) | 468 (70%) | 211 (65%) | 0.17 | |
| Meeting modified New York criteria | 597 (60%) | 394 (59%) | 203 (63%) | 0.24 | |
| Mean age at symptom onset, years | 28.6 (11.3) | 28.3 (10.9) | 29.4 (12.1) | 0.13 | |
| Mean symptom duration, years | 16.0 (12.6) | 14.7 (12.0) | 18.9 (13.4) | <0.001 | |
| HLA-B27 positivea | 540 (74%) | 382 (76%) | 158 (71%) | 0.12 | |
| Mean BMI, kg/m2 | 28.1 (5.8) | 27.5 (5.6) | 29.2 (6.1) | <0.001 | |
| Smoking status | Never smoked | 351 (40%) | 251 (42%) | 100 (35%) | 0.093 |
| Ex-smoker | 291 (33%) | 188 (32%) | 103 (36%) | ||
| Current smoker | 241 (27%) | 155 (26%) | 86 (30%) | ||
| Education | Secondary school | 289 (33%) | 184 (31%) | 105 (36%) | 0.022b |
| Apprenticeship | 82 (9%) | 56 (10%) | 26 (9%) | ||
| Further education college | 276 (31%) | 175 (30%) | 101 (35%) | ||
| University degree | 178 (20%) | 138 (23%) | 40 (14%) | ||
| Further degree | 53 (6%) | 36 (6%) | 17 (6%) | ||
| IMD, median (IQR) | 3.0 (2.0, 4.0) | 3.0 (2.0, 4.0) | 3.0 (2.0, 4.0) | 0.12 | |
| NSAID use in past 6 months | 734 (75%) | 509 (77%) | 225 (70%) | 0.023 | |
| DMARD use in past 6 months | 146 (15%) | 104 (16%) | 42 (13%) | 0.29 | |
| BASDAI, median (IQR) | 6.7 (5.3, 7.8) | 6.5 (5.1, 7.7) | 7.2 (6.0, 8.2) | <0.001 | |
| Spinal pain, median (IQR) | 7.0 (5.0, 8.0) | 7.0 (5.0, 8.0) | 7.0 (6.0, 8.0) | <0.001 | |
| ASDAS, mean (s.d.)a | 2.9 (0.8) | 2.8 (0.8) | 3.0 (0.8) | <0.001 | |
| BASFI, median (IQR) | 6.5 (4.5, 8.1) | 6.1 (4.1, 7.7) | 7.1 (5.4, 8.6) | <0.001 | |
| ASQoL, median (IQR) | 13.0 (9.0, 16.0) | 12.0 (8.0, 15.0) | 14.0 (11.0, 17.0) | <0.001 | |
| Fatigue, median (IQR) | 17.5 (14.0, 21.0) | 17.0 (13.0, 21.0) | 19.0 (15.0, 23.0) | <0.001 | |
| Sleep, median (IQR) | 14.0 (8.0, 18.0) | 13.0 (8.0, 17.0) | 15.0 (10.0, 19.0) | 0.003 | |
a
Data shown as mean (s.d.) and n (%) unless otherwise indicated. bCuzick non-parametric test for trend. ASDAS: AS disease activity score; ASQoL: AS quality of life questionnaire; BASDAI: Bath AS disease activity index; BASFI: Bath AS functional index; IMD: index of multiple deprivation; IQR: interquartile range.