Table 1 Baseline characteristics and causes of discontinuation among 758 participants, according to smoking status
Never smoker (n = 224) | Ex-smoker (n = 177) | Current smoker (n = 197) | P value | ||
|---|---|---|---|---|---|
Age, mean (SD) years | 43.3 (14.5) | 50.0 (12.8) | 42.2 (11.8) | < 0.001 | |
Male | 167 (62%) | 149 (65%) | 188 (73%) | 0.012 | |
Meets mNY criteria for AS | 164 (61%) | 154 (67%) | 162 (63%) | 0.360 | |
HLA-B27 positive+ | 143 (70%) | 125 (76%) | 148 (80%) | 0.088 | |
Elevated CRP* | 150 (57%) | 129 (59%) | 161 (67%) | 0.043 | |
Age at symptom onset, median (IQR) years | 26.0 (20.0 to 33.0) | 26.0 (22.0 to 34.0) | 26.0 (21.0 to 33.0) | 0.350 | |
Symptom duration, median (IQR) years | 12.4 (4.2 to 26.0) | 20.7 (10.3 to 32.5) | 12.3 (5.5 to 22.9) | < 0.001 | |
BMI, mean (SD) | 27.9 (6.2) | 28.8 (5.1) | 27.4 (5.8) | 0.060 | |
Quintiles of Index of Multiple Deprivation | 1, most deprived | 39 (14%) | 33 (14%) | 85 (33%) | < 0.001** |
2 | 54 (20%) | 30 (13%) | 43 (17%) | ||
3 | 52 (19%) | 53 (23%) | 51 (20%) | ||
4 | 68 (25%) | 56 (24%) | 47 (18%) | ||
5, most affluent | 58 (21%) | 59 (26%) | 30 (12%) | ||
Highest level of education | Secondary school | 72 (27%) | 75 (33%) | 114 (45%) | < 0.001 |
Apprenticeship | 18 (7%) | 24 (10%) | 29 (12%) | ||
Further education college | 83 (31%) | 81 (35%) | 71 (28%) | ||
University degree | 70 (26%) | 38 (17%) | 29 (12%) | ||
Further degree | 26 (10%) | 11 (5%) | 9 (4%) | ||
Alcohol status | Never | 31 (11%) | 14 (6%) | 30 (12%) | < 0.001 |
Ex | 34 (13%) | 43 (19%) | 68 (27%) | ||
Current | 205 (76%) | 174 (75%) | 158 (62%) | ||
Number of comorbidities | 0 | 163 (61%) | 117 (51%) | 137 (54%) | 0.051** |
1 | 77 (29%) | 68 (30%) | 78 (30%) | ||
≥ 2 | 28 (10%) | 43 (19%) | 41 (16%) | ||
BASDAI, median (IQR) | 6.3 (4.8 to 7.4) | 6.6 (5.2 to 7.9) | 7.1 (5.5 to 7.9) | 0.001 | |
Spinal pain, median (IQR) | 6.0 (4.0 to 8.0) | 7.0 (5.0 to 8.0) | 7.0 (5.0 to 8.0) | 0.002 | |
BASFI, median (IQR) | 5.7 (3.7 to 7.6) | 6.6 (4.8 to 8.3) | 7.0 (5.1 to 8.6) | < 0.001 | |
Chalder Fatigue Scale, median (IQR) | 17.0 (14.0 to 21.0) | 17.0 (13.0 to 21.0) | 18.0 (13.0 to 22.0) | 0.340 | |
Remained on treatment | 62 (23%) | 49 (21%) | 63 (25%) | 0.670 | |
Stopped treatment | Infection | 20 (32%) | 18 (37%) | 15 (24%) | 0.176 |
Other adverse events | 17 (27%) | 15 (31%) | 13 (21%) | ||
Inefficacy or other reasons | 25 (40%) | 16 (33%) | 33 (56%) | ||