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Table 2 Differences in clinical and patient reported characteristics (not used in clustering) across clusters (total population)

From: AxSpA patients who also meet criteria for fibromyalgia: identifying distinct patient clusters using data from a UK national register (BSRBR-AS)

  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
  1. *significant difference between cluster 3 & 4 at p < 0.05