Use of Numeric Rating Scale (NRS) as Visual Analogue Scale (VAS): Is this Clinically Significant?

Objective: To analyze statistically significant differences between the Numeric Rating Scale (NRS) and Visual Analogue Scale (VAS) in low back pain (LBP) patients. Study Design: Prospective longitudinal Study. Place and Duration of Study: Orthopaedic and Spine Department, Combined Military Hospital, Peshawar Pakistan, from Sep 2019 to May 2020. Methodology: The study included two hundred one patients with low back pain presented to the Orthopedic and Spine OPD.All patients were asked to record their pain with a Visual Analogue Scale (VAS) at the start of the visit and a Numerical Rating Scale (NRS) at the exit, at approximately 5-7 minute intervals in the Outpatient Department. Results: Two hundred one patients were included in the study. The mean age of the patients was 41.5 years (range 15-75). Thecomparison of pain measurements with the Numerical Rating Scale (NRS) showed a mean of 7.408(SD1.853), whereas with the Visual Analogue Scale (VAS), it was 6.864 (SD1.954). This showed higher readings with NRS compared to VAS, with a mean difference of 0.544 (p-value was <0.001). Conclusion: The numerical Rating Scale (NRS) tends to produce higher pain readings than the Visual Analogue Scale (VAS). Treatment guidelines should be considered when interpreting studies that have used VAS interchangeably and wrongly reported it as NRS.