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Table 1 Outcome and predictor variables

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

  Outcome measurement tool Logistic multivariable analysis categories
Outcome variables (Pre-operative/6 months)
Physical function Oswestry Disability Questionnaire (ODQ) (0–100) 1. <SCB (18.8) 2. ≥ SCB (18.8)
  SF-36 Physical Component Summary (SF-36 PCS) (0–100) 1. <SCB (− 6.2) 2. ≥ SCB (−6.2)
Back Pain Numerical pain rating scale (NRPS) (0–10) 1. <SCB (2.5) 2. ≥SCB (2.5)
Leg Pain Numerical pain rating scale (NRPS) (0–10) 1. <SCB (2.5) 2. ≥SCB (2.5)
Predictor variables
Total walking time (1st 7 post-op days) ActivPAL3 accelerometer Hours (continuous)
Age 1. < 65 years 2. ≥65 years
Sex 1. Male 2. Female
Current smoking status 1. Non-smoker 2. Smoker
Obesity Body Mass Index (BMI) 1. BMI < 30 2. BMI ≥30
Diabetes 1. Not diabetic 2. Diabetic
Depression Patient Health Questionnaire Depression Scale (PHQ-9) 1. No depression: PHQ-9 < 10 2. Increased likelihood of depression: PHQ-9 ≥ 10
Anxiety Generalised Anxiety Disorder 7 Item Scale (GAD-7) 1. No anxiety: PHQ-9 < 10 2. Increased likelihood of anxiety: PHQ-9 ≥ 10
Pre-operative pain duration 1. < 12 months 2. ≥12 months
Neurological deficit Self-report 1. No deficit 2. Sensory/motor deficit
Pre-operative activity International Physical Activity Questionnaire Short Form (IPAQ-SF) 1. Moderate/high activity 2. Low activity
Pre-operative mobility ODQ, Section 4 (restricted mobility: score ≥ 3: unable to walk more than 500 m, or requires a stick, crutches or other support) 1. Unrestricted mobility 2. Restricted mobility
Pre-operative function ODQ classification (%) 1. 0–20% 2. 21–40% 3. 41–60% 4. 61–80% 5. 81–100%
Surgical procedure 1. Decompression 2. Discectomy 3. Fusion
Number of vertebral levels 1. Single level 2. Multi-level
  1. SCB Substantial Clinical Benefit