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Table 3 Patient baseline characteristics per group in the study on standardized consultation for patients with osteoarthritis of the knee (second motivating example)

From: Propensity score to detect baseline imbalance in cluster randomized trials: the role of the c-statistic

Characteristics Control Standardized consultation p SDiff (%)
  n 0 =146 n 1=181   
  mean (standard deviation) mean (standard deviation)   
Age (years) 64.5 (8.4) 63.9 (8.1) 0.4720 8.02
Weight (kg) 81.4 (13.6) 84.1 (12.9) 0.0665 20.60
BMI (kg.m −2) 30.2 (3.8) 31.2 (3.5) 0.0143 27.63
PEL (0-5) 2.2 (0.9) 2.2 (0.8) 0.9594 0.00
Delay since beginning of pain (years) 5.5 (5.9) 7.4 (7.5) 0.0152 27.57
Age at beginning of pain (years) 59.1 (10.4) 56.5 (10.5) 0.0300 24.28
Pain (0-10) 5.6 (1.3) 5.5 (1.2) 0.3646 10.38
WOMAC function score (0-100) 29.9 (12.2) 30.3 (11.7) 0.7377 3.76
SF-12 physical subscale 34.8 (6.7) 35.4 (6.7) 0.4385 8.70
SF-12 mental subscale 41.4 (9.4) 43.3 (10.1) 0.0827 19.31
Global assessment of disease status (0-10) 5.6 (1.5) 5.6 (1.5) 0.9133 1.31
  n (%) n (%)   
Male 49 (27.1) 34 (23.3) 0.5132 8.73
Prior treatments     
Analgesics 130 (71.8) 96 (65.8) 0.2889 13.13
NSAIDs 95 (52.5) 90 (61.6) 0.1215 18.58
Current use of NSAIDS 160 (88.4) 126 (86.3) 0.6883 6.31
SYSADOA 74 (40.9) 68 (46.6) 0.3576 11.49
Current use of SYSADOA 179 (98.9) 145 (99.3) 1.0000 4.46
IA treatment 31 (17.1) 29 (19.9) 0.6229 7.05
Non-drug treatment 110 (60.8) 71 (48.6) 0.0372 24.58
Diet 49 (27.1) 31 (21.2) 0.2750 13.67
Dietetician 12 (6.6) 7 (4.8) 0.6401 7.91
Physical exercice 44 (24.3) 27 (18.5) 0.2571 14.22
Physiotherapy 30 (16.6) 17 (11.6) 0.2692 14.20
Knee orthosis 21 (11.6) 11 (7.5) 0.2967 13.86
Insoles 24 (13.3) 11 (7.5) 0.1376 18.84
Walking sticks 13 (7.2) 10 (6.8) 1.0000 1.30
  1. BMI: Body Mass Index; PEL: Baecke’s physical exercice level scale; WOMAC: Western Ontario and McMaster Universities Arthritis Index; SF-12: 12-items Short Form; IA: intra-articular; NSAID: non-steroidal anti-inflammatory drug; SYSADOA: systematic slow acting drug for osteoarthritis. SDiff: standardized difference; p: p-value for univariate tests (adjusted t test for quantitative variables, adjusted chi-square test for qualitative variables to take the clustering into account). Bold values are significant tests at a 5 % significance level