Table 2

Effect of age, gender and height on spinal mobility measures

MeasureUnivariable linear regression
β (95% CI)
Multivariable linear regression
β (95% CI)*
Clinically relevant†
Tragus-to-wall (cm)
 Age (years)0.02 (0.01 to 0.03)0.02 (0.01 to 0.03)
 Gender (female vs male)−0.7 (−1.0 to −0.5)
 Height (cm)0.04 (0.03 to 0.05)0.02 (0.01 to 0.03)
Occiput-to-wall (cm)
 Age (years)0.02 (0.01 to 0.03)0.02 (0.01 to 0.02)
 Gender (female vs male)−0.24 (−0.43 to −0.04)
 Height (cm)0.01 (0.01 to 0.02)
ASAS lateral spinal flexion (cm)
 Age (years)−0.15 (−0.17 to −0.13)−0.15 (−0.17 to −0.13)
 Gender (female vs male)−0.50 (−1.23 to 0.23)
 Height (cm)0.03 (0.00 to 0.06)0.03 (0.00 to 0.07)
INSPIRE lateral spinal flexion (cm)
 Age (years)−0.24 (−0.27 to −0.20)−0.24 (−0.27 to −0.20)
 Gender (female vs male)−0.92 (−2.10 to 0.26)
 Height (cm)0.03 (−0.02 to 0.08)
Chest expansion (cm)
 Age (years)−0.03 (−0.05 to −0.01)Men: −0.02 (−0.04 to −0.01)
Women: –
 Gender (female vs male)−1.16 (−1.58 to −0.73)
 Height (cm)0.07 (0.06 to 0.09)Men: 0.11 (0.08 to 0.14)
Women: 0.11 (0.09 to 0.14)
Cervical rotation, sitting (degrees)
 Age (years)−0.35 (−0.42 to −0.27)−0.34 (−0.42 to −0.27)
 Gender (female vs male)−4.13 (−6.43 to −1.82)−3.83 (−5.89 to −1.77)
 Height (cm)0.12 (0.03 to 0.21)
Cervical rotation, lying (degrees)
 Age (years)−0.35 (−0.41 to −0.30)−0.34 (−0.39 to −0.29)
 Gender (female vs male)2.11 (0.38 to 3.83)
 Height (cm)0.02 (−0.05 to 0.09)
Intermalleolar distance (cm)
 Age (years)−0.46 (−0.42 to −0.27)Men: −0.36 (−0.48 to −0.24)
Women: −0.52 (−0.64 to −0.40)
 Gender (female vs male)−1.05 (−3.92 to 1.83)
 Height (cm)0.44 (0.33 to 0.55)Men: 0.43 (0.28 to 0.58)
Women: 0.56 (0.41 to 0.72)
Internal hip rotation (cm)
 Age (years)−0.14 (−0.21 to −0.08)Men: –
Women: −0.17 (−0.25 to −0.09)
 Gender (female vs male)7.80 (6.04 to 9.56)
 Height (cm)0.12 (0.05 to 0.20)Men: 0.50 (0.37 to 0.63)
Women: 0.34 (0.21 to 0.46)
10 cm Schober test (cm)
 Age (years)−0.01 (−0.02 to −0.00)−0.01 (−0.02 to −0.01)
 Gender (female vs male)−0.33 (−0.53 to −0.13)
 Height (cm)0.00 (−0.01 to 0.01)
15 cm Schober test (cm)
 Age (years)−0.02 (−0.03 to −0.01)Men: −0.02 (−0.03 to −0.01)
Women: −0.02 (−0.03 to −0.01)
 Gender (female vs male)−0.33 (−0.57 to −0.10)
 Height (cm)0.00 (−0.01 to 0.01)
BASMI-original (0–10)‡
 Age (years)0.03 (0.03 to 0.04)Men: 0.03 (0.02 to 0.04)
Women: 0.03 (0.03 to 0.04)
 Gender (female vs male)0.08 (−0.08 to 0.24)
 Height (cm)−0.01 (−0.01 to −0.00)
BASMI-modified (0–10)§
 Age (years)0.03 (0.03 to 0.04)Men: 0.03 (0.02 to 0.04)
Women: 0.03 (0.03 to 0.04)
 Gender (female vs male)0.21 (0.05 to 0.38)
 Height (cm)−0.01 (−0.02 to −0.00)
  • *Analyses were adjusted for weight, where needed (tragus-to-wall distance, occiput-to-wall distance, ASAS lateral spinal flexion, chest expansion, cervical rotation (lying), internal hip rotation, 10 cm Schober test, 15 cm Schober test, BASMI-original, BASMI-modified).

  • †Clinical relevance of the effect of each factor on each of the measurements according to the authors’ clinical judgement.

  • ‡BASMI-original: calculated with cervical rotation in lying position and 15 cm Schober test.

  • §BASMI-modified: calculated with cervical rotation in sitting position and 10 cm Schober test.

  • ASAS, Assessment in Spondyloarthritis international Society; BASMI, Bath Ankylosing Spondylitis Metrology Index.