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Table 1 Characteristics of the study population

From: Association between ultrasound-detected synovitis and knee pain: a population-based case–control study with both cross-sectional and follow-up data

  No knee pain Early knee pain Established knee pain p value
N 94 298 103  
Age (years), mean (SD) 60.98 (9.81) 61.42 (9.66) 59.53 (10.04) 0.2992*
Women, n (%) 58 (61.70) 179 (60.07) 63 (61.17) 0.9509**
BMI (kg/m2), mean (SD) 26.78 (4.49) 28.85 (5.70) 31.96 (6.49) <  0.0001*
Pain severity (NRS 0–10)a, mean (SD)   4.55 (2.52) 7.40 (2.14) < 0.0001
Global X-ray score (mm, 0–60), mean (SD) 2.24 (3.08) 5.72 (7.00) 11.28 (9.26) < 0.0001*
Radiographic OA, n (%) 7 (7.45) 80 (26.85) 49 (47.57) < 0.0001**
Muscle strengthb, n (%)
 Quadriceps strength (kg, lowest tertile) 33 (35.11) 99 (33.22) 65 (63.11) < 0.0001**
 Hip abductor strength (kg, lowest tertile) 33 (35.11) 119 (39.93) 68 (66.02) < 0.0001**
Use of analgesics, n (%)
 Prescribed NSAIDs 3 (3.19) 19 (6.38) 15 (14.56) 0.0018
 Opioids 3 (3.19) 44 (14.77) 22 (21.36) 0.0005
 Over-the-counter NSAIDs 12 (12.77) 68 (22.82) 32 (31.07) 0.0021
  1. Groups matched by age and gender. p values adjusted for multiple testing using the bootstrap method
  2. SD standard deviation, NRS numerical rating scale, BMI body mass index, OA osteoarthritis, NSAID non-steroidal anti-inflammatory drug
  3. t test
  4. *Test for linear trend
  5. **Cochran–Armitage test for trend
  6. aAverage pain severity in the past month
  7. bLowest tertile values for muscle strength tests: quadriceps strength < 17.6 kg for men and < 10.7 kg for women; hip abductor strength < 12.8 kg and < 8.2 kg, respectively