Table 1 Outcome measures (unit) and description of measurement properties, including references relating to reliability and validity.
Outcome measure | Measurement properties | |
|---|---|---|
Primary outcome | ||
Multifidus cross-sectional area (CSA, cm2) | Multifidus muscle cross-sectional area measurements are obtained from ultrasound (US) from the L4/L5 spinal level (left and right) | |
Multifidus muscle thickness (MT, cm) | Multifidus muscle thickness is measured with ultrasound (US) from the L4/L5 spinal level (left and right) | |
Multifidus echo intensity (EI, 0–255 AU) | Multifidus echo intensity (EI) is measured with ultrasound (US) from the cross-sectional area of the L4/L5 spinal level (left and right). EI is measured on a scale from 0–255 in arbitrary units (ImageJ) | |
Secondary outcomes | ||
Pain intensity (mm, 0–100) | Pain intensity is measured with the visual analog scale (VAS) on a rating scale from 0 – 100 | |
Health-related quality of life (pts., 0–100) | Health-related quality of life (QoL) is measured with the short-form survey 36 (SF-36). The survey consists of 8 domains assessing physical and mental sum scores (SF-P and SF-M). Scores in each domain can range from 0 (zero health) to 100 (perfect health) | |
Disability (pts., 0–50) | Disability concerning LBP is measured with the Oswestry Disability Index (ODI). It includes 10 items (e.g., sitting, standing, personal care) with a range from 0–5 with higher scores indicating greater disability | |
Function (isokinetic machine)32 | Isometric lumbar extensor muscle strength (Nm) | Isometric lumbar extensor strength is measured with an isokinetic dynamometer included in the Powerspine Back ILEX device. Measurements were taken at 39°, 30°, 24° and 15° |
