Table 2:

Coefficients of taper ratios as a function of age for Chiari, IS, and control patients from final multivariate modela

ParameterSlope Estimate in ModelStandard ErrorP Value
Taper ratio
    Chiari0.01 mm/level0.1881.0
    Controls−0.03 mm/level0.178.8
    Chiari + syrinx−0.3 mm/level0.194.14
    IS0.3 mm/level0.214.21
Effect of age on taper ratio
    Chiari−0.03 mm/level/year of age0.010.009
Effect of age2 on taper ratio
    Chiari0.0003 mm/level/year of age20.0001.01
Effect of age on taper ratio
    Controls0.003 mm/level/year of age0.005.5
    Chiari + syrinx0.0003 mm/level/year of age0.0061.0
    IS−0.03 mm/level/year of age0.010.003
Effect of age2 on taper ratio
    IS0.0003/level/year of age20.0001.01
  • a Age and the presence of a Chiari malformation affect spinal canal taper ratios, with both variables interacting. The multivariate analysis estimates the taper ratio (millimeter/level) for Chiari patients as equal to −0.445–0.009 (age of patient in years), for the controls as −0.114–0.074 (age of the patient in years), and for the IS group as 0.191–0.039 (age of the patient in years).