Table 4.

Multiple regression analysis with change in ODI at 1 year as the dependent variable

Variable	Parameter estimate	95% confidence interval	p value
Adolescent	3.4	−4.5, 4.6	0.103
Oswestry score, pre-surgery	0.9	0.8, 0.9	<0.001
Smoking	−5.7	−7.2, −4.3	<0.001
ASA grade >2	−8.7	−14.5, −2.9	0.003
Female sex	−1.8	−3.1, −0.4	0.010
BMI	−0.2	−0.4, −0.05	0.011

A negative score means a worsening of ODI score 1 year after surgery