Predictors of substantial improvement in physical function six months after lumbar surgery: is early post-operative walking important? A prospective cohort study

Table 6 Multivariable logistic regression analysis

Outcome measure	Variable	β	Exp (β)	(95% CI)
ODQ	Total post-operative walking time (hours)	0.16	1.18	(1.02–1.37)
	Pre-operative pain duration < 12 months	1.00	2.71	(1.28–5.74)
	Pre-operative function (ODQ categories^a)	1.39	4.02	(2.33–6.93)
SF-36 (PCS)	Age < 65	0.86	2.36	(1.14–4.85)
SF-36 (PCS)	Pre-operative pain duration < 12 months	1.26	3.52	(1.69–7.33)

Interpretation of results: Exp (β) is equivalent to the odds ratio (OR). The predictor variables may be applied to determine the odds of achieving the SCB threshold for the given outcome measure. For example, for each additional hour of walking the odds of achieving ODQ SCB increases by 18%; for a participant less than 65 years old, the odds of achieving the SF-36 (PCS) SCB is 2.36 greater than those 65 years or over
ODQ, Oswestry Disability Questionnaire; SF-36 (PCS), Short Form 36 Physical Component Summary; ^aODQ categories: 1: 0–20, 2: 21–40, 3: 41–59, 4: 60–79, 5: 80–100 (reference value: ODQ score 0–20)

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