| Cluster 1 | Cluster 2 | Cluster 3 | Cluster 4 | p value |
N (%) | N (%) | N (%) | N (%) | ||
Categorical variable | |||||
 Gender | |||||
  male | 13 (40.6) | 209 (60.2) | 297 (69.6) | 298 (64.5) | p < 0.001 |
  female | 19 (59.4) | 138 (39.8) | 130 (30.4) | 164 (35.5) | |
 Smoking Status | |||||
  never | 10 (31.2) | 129 (37.6) | 201 (47.4) | 214 (46.8) | p < 0.001 |
  ex | 14 (43.8) | 116 (33.8) | 168 (39.6) | 180 (39.4) | |
  current | 8 (25.0) | 98 (28.6) | 55 (13.0) | 63 (13.8) | |
 Alcohol Use | |||||
  never | 1 (3.1) | 39 (11.4) | 20 (4.7) | 25 (5.5) | p < 0.001 |
  ex | 9 (28.1) | 94 (27.5) | 41 (9.7) | 63 (13.9) | |
  current | 22 (68.8) | 209 (61.1) | 361 (85.6) | 366 (80.6) | |
 Employed | |||||
  no | 15(46.9) | 164 (47.3) | 113 (26.5) | 160 (34.9)* | p < 0.001 |
  yes | 17 (53.1) | 183 (52.7) | 314 (73.5) | 299 (65.1) | |
 Job type | |||||
  mainly sedentary | 8 (50.0) | 81 (45.5) | 171 (56.1) | 179 (61.5) | p = 0.009 |
  mainly physical | 8 (50.0) | 97 (54.5) | 134 (43.9) | 112 (38.5) | |
 Current biologic therapy | |||||
  no | 22 (68.8) | 211 (61.0) | 364 (86.3) | 350 (76.1)* | p < 0.001 |
  yes | 10 (31.2) | 135 (39.0) | 58 (13.7) | 110 (23.9) | |
 NSAID (last 6 m) | |||||
  no | 7 (21.9) | 114 (32.9) | 136 (31.9) | 142 (30.7) | p = 0.611 |
  yes | 25 (78.1) | 233 (67.1) | 291 (68.1) | 320 (69.3) | |
 DMARD use in past 6 m | |||||
  no | 21 (65.6) | 305 (87.9) | 374 (87.6) | 401 (86.8) | p = 0.004 |
  yes | 11 (34.4) | 42 (12.1) | 53 (12.4) | 61 (13.2) | |
 HLA B27 status | |||||
  positive | 20 (62.5) | 148 (42.7) | 260 (60.9) | 242 (52.4)* | p < 0.001 |
  negative | 7 (21.9) | 58 (16.7) | 52 (12.2) | 66 (14.3) | |
  untested | 5 (15.6) | 141 (40.6) | 115 (26.9) | 154 (33.3) | |
 | Mean (95% CI) | Mean (95% CI) | Mean (95% CI) | Mean (95% CI) |  |
Age | |||||
 years | 49.5 (45.2, 53.8) | 47.5 (46.0, 48.9) | 49.4 (48.1, 50.7) | 50.3 (48.9, 51.6) | p = 0.062 |
Age at symptom onset | |||||
 years | 31.7 (27.7, 35.7) | 30.7 (29.3, 32.0) | 28.8 (27.8, 29.8) | 29.7 (28.6, 30.8) | p = 0.074 |
Disease Activity | |||||
 BASDAI: 0 (best) – 10 (worst) | 6.7 (5.9, 7.4) | 6.7 (6.5, 6.9) | 2.5 (2.3, 2.6) | 4.5 (4.3, 4.7)* | p < 0.001 |
Disease Activity | |||||
 ASDAS Score | 3.6 (3.2, 4.0) | 3.7 (3.6, 3.8) | 2.2 (2.1, 2.3) | 2.9 (2.7, 3.0)* | p < 0.001 |
Physical Function | |||||
 BASFI: 0 (best) – 10 (worst) | 6.2 (5.4, 6.9) | 6.5 (6.3, 6.8) | 2.5 (2.3, 2.7) | 4.3 (4.0, 4.5)* | p < 0.001 |
Spinal Mobility | |||||
 BASMI: 0 (best) – 10 (worst) | 4.2 (3.6, 4.8) | 4.1 (3.8, 4.3) | 3.4 (3.2, 3.6) | 3.7 (3.4, 3.9) | p < 0.001 |
Patient Global | |||||
 BASG: 0 (best) – 10 (worst) | 6.9 (6.2, 7.5) | 7.0 (6.8, 7.2) | 2.6 (2.4, 2.8) | 4.6 (4.3, 4.8)* | p < 0.001 |
Spinal Pain | |||||
 VAS: 0 (best) – 10 (worst) | 5.1 (4.1, 6.2) | 6.3 (6.1, 6.6) | 2.2 (2.0, 2.4) | 4.0 (3.7, 4.2)* | p < 0.001 |
SF12 Mental Component | |||||
 100 (best) – 0 (worst) | 37.6 (33.0, 42.1) | 35.2 (34.3, 36.1) | 54.0 (53.3, 54.6) | 47.2 (46.3, 48.0)* | p < 0.001 |
SF12 Physical Component | |||||
 100 (best) – 0 (worst) | 32.3 (29.3, 35.3) | 32.3 (31.2, 33.4) | 46.2 (45.3, 47.1) | 39.4 (38.4, 40.5)* | p < 0.001 |
Quality of Life | |||||
 ASQoL: 0 (best) – 18 (worst)) | 12.9 (11.3, 14.4) | 13.3 (12.9, 13.7) | 3.0 (2.7, 3.3) | 7.9 (7.5, 8.3)* | p < 0.001 |
Work absence | |||||
 absenteeism (%) | 17.4 (0.1, 34.7) | 11.2 (7.7, 14.6) | 0.4 (0.1, 0.7) | 4.4 (2.6, 6.1)* | p < 0.001 |
Work impairment | |||||
 presenteeism (%) | 48.6 (36.4, 60.7) | 52.5 (49.0, 56.1) | 15.1 (13.1, 17.0) | 28.8 (26.3, 31.4)* | p < 0.001 |
Overall work impairment | |||||
 (%) | 48.8 (35.7, 62.0) | 55.1 (51.3, 58.9) | 15.4 (13.4, 17.5) | 30.4 (27.7, 33.2)* | p < 0.001 |
Other activity impairment | |||||
 (%) | 63.1 (53.8, 72.4) | 65.4 (63.1, 67.6) | 19.8 (17.9, 21.7) | 38.4 (36.1, 40.6)* | p < 0.001 |