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Table 1 Baseline characteristics of paid workers and house workers (unadjusted data) (modified intention-to-treat set)

From: Effect of subcutaneous tocilizumab treatment on work/housework status in biologic-naïve rheumatoid arthritis patients using inverse probability of treatment weighting: FIRST ACT-SC study

  Paid worker House worker
  TCZ-SC group
(n = 167)
csDMARDs-alone group
(n = 160)
Standardized difference
csDMARDs vs TCZ-SC
TCZ-SC group
(n = 154)
csDMARDs-alone group
(n = 148)
Standardized difference
csDMARDs vs TCZ-SC
Sex, female, n (%) 126 (75.4) 125 (78.1) 0.063 136 (88.3) 139 (93.9) 0.198
Age (years), mean (SD) 51.5 (12.1) 55.0 (11.5) 0.299 64.5 (12.6) 65.5 (12.0) 0.085
Weight (kg), mean (SD) 57.01 (11.65) 56.02 (11.35) −0.086 52.43 (9.22) 51.87 (10.16) −0.058
Disease duration (years), mean (SD) 5.77 (8.23) 4.36 (5.83) −0.197 8.09 (10.58) 5.99 (7.76) −0.226
Incomea, n (%)
  < 1,000,000 yen 5 (3.0) 8 (5.0) 0.103 15 (9.7) 13 (8.8) −0.033
 1,000,000–< 2,000,000 yen 12 (7.2) 17 (10.6) 0.121 24 (15.6) 20 (13.5) −0.059
 2,000,000–< 3,000,000 yen 18 (10.8) 23 (14.4) 0.109 35 (22.7) 24 (16.2) −0.165
 3,000,000–< 5,000,000 yen 50 (29.9) 49 (30.6) 0.015 49 (31.8) 40 (27.0) −0.105
 5,000,000–< 7,000,000 yen 37 (22.2) 25 (15.6) −0.167 17 (11.0) 19 (12.8) 0.056
  ≥ 7,000,000 yen 42 (25.1) 36 (22.5) −0.062 14 (9.1) 24 (16.2) 0.216
 Unknown 3 (1.8) 2 (1.3) −0.045 0 (0.0) 8 (5.4) 0.338
Job, n (%)
 Full-time/unknown 81 (48.5) 72 (45.0) −0.070
 Part-time 51 (30.5) 58 (36.3) 0.121
 Private business 35 (21.0) 30 (18.8) −0.055
 Housework 154 (100.0) 148 (100.0)
Methotrexate, n (%) 130 (77.8) 153 (95.6) 0.543 98 (63.6) 133 (89.9) 0.653
Steinbrocker stage, n (%)
 Stage I 69 (41.3) 71 (44.4) 0.062 33 (21.4) 55 (37.2) 0.351
 Stage II 54 (32.3) 60 (37.5) 0.108 66 (42.9) 46 (31.1) −0.246
 Stage III 22 (13.2) 17 (10.6) −0.079 30 (19.5) 21 (14.2) −0.142
 Stage IV 22 (13.2) 12 (7.5) −0.187 25 (16.2) 26 (17.6) 0.036
Steinbrocker class, n (%)
 Class 1 43 (25.7) 59 (36.9) 0.242 24 (15.6) 40 (27.0) 0.282
 Class 2 114 (68.3) 95 (59.4) −0.186 107 (69.5) 97 (65.5) −0.084
 Class 3/4 10 (6.0) 6 (3.8) −0.104 23 (14.9) 11 (7.4) −0.240
DAS28-ESR, mean (SD) 5.110 (1.261) 4.527 (0.991) −0.514 5.546 (1.183) 4.882 (1.008) −0.605
CDAI, mean (SD) 23.995 (11.588) 17.823 (8.713) −0.602 26.773 (13.514) 19.053 (10.120) −0.647
SDAI, mean (SD) 25.902 (2.852) 19.086 (9284) −0.608 31.075 (26.411) 20.868 (10.805) −0.506
Rheumatoid factor, n (%)
 Positive 112 (67.1) 100 (62.5) −0.020 99 (64.3) 95 (64.2) − 0.150
 Negative 32 (19.2) 30 (18.8) 0.020 24 (15.6) 33 (22.3) 0.150
ACPA, n (%)
 Positive 100 (59.9) 78 (48.8) −0.104 90 (64.3) 95 (64.2) −0.123
 Negative 26 (15.6) 26 (16.3) 0.104 18 (11.7) 20 (13.5) 0.123
WPAI
 Absenteeism = 0, n (%) 117 (70.1) 118 (73.8) 0.082
 Absenteeism > 0, n (%) 44 (26.3) 37 (23.1) −0.075
 Presenteeism (%), mean (SD) 45.9 (32.2) 34.8 (26.9) −0.373
 OWI (%), mean (SD) 48.7 (32.9) 37.0 (29.2) −0.346
 AI (%), mean (SD) 53.6 (31.6) 40.8 (26.7) −0.440 58.8 (27.5) 45.2 (27.9) −0.492
WFun, mean (SD) 16.4 (8.7) 14.0 (7.5) −0.290
EQ-5D, mean (SD) 0.596 (0.140) 0.656 (0.137) 0.434 0.564 (0.152) 0.654 (0.163) 0.569
HAQ-DI, mean (SD) 0.917 (0.709) 0.643 (0.585) −0.421 1.255 (0.759) 0.959 (0.647) −0.419
  1. a100 yen = 0.9 US$
  2. ACPA antibodies to citrullinated peptide antigens, CDAI clinical disease activity index, csDMARD conventional synthetic disease-modifying antirheumatic drug, DAS28-ESR disease activity score in 28 joints using the erythrocyte sedimentation rate, EQ-5D EuroQol 5 dimension, HAQ-DI health assessment questionnaire disability index, SD standard deviation, SDAI simplified disease activity index, TCZ-SC tocilizumab by subcutaneous injection, WFun work functioning impairment scale, WPAI work productivity and activity impairment questionnaire