Effect of age, gender and height on spinal mobility measures
| Measure | Univariable 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.