Chiarotto A, et al. - Researchers systematically reviewed the measurement properties of Visual Analogue Scale (VAS), Numeric Rating Scale (NRS), and Pain Severity subscale of the Brief Pain Inventory (BPI-PS)], the most frequently used instruments to measure pain intensity in low back pain (LBP). Low or very low-quality evidence for content validity was gained for the three instruments. They identified high-quality evidence only for NRS insufficient measurement error. They gained moderate evidence for NRS inconsistent responsiveness, BPI-PS sufficient structural validity and internal consistency, and BPI-PS inconsistent construct validity. No, low or very low quality evidence underpinned all VAS measurement properties, likewise the other measurement properties of NRS and BPI-PS.