Responsiveness of the numeric pain rating scale in patients with low back pain

Spine (Phila Pa 1976). 2005 Jun 1;30(11):1331-4. doi: 10.1097/01.brs.0000164099.92112.29.


Study design: Cohort study of patients with low back pain (LBP) receiving physical therapy.

Objective: To examine the responsiveness characteristics of the numerical pain rating scale (NPRS) in patients with LBP using a variety of methods.

Summary of background data: Although several studies have assessed the reliability and validity of the NPRS, few studies have characterized its responsiveness in patients with LBP.

Methods: Determination of change on the NPRS during 1 and 4 weeks was examined by calculating mean change, standardized effect size, Guyatt Responsiveness Index, area under a receiver operating characteristic curve, minimum clinically important difference, and minimum detectable change. Change in the NPRS from baseline to the 1 and 4-week follow-up was compared to the average of the patient and therapist's perceived improvement using the 15-point Global Rating of Change scale.

Results: The majority of patients had clinically meaningful improvement after both 1 and 4 weeks of rehabilitation. The standard error of measure was equal to 1.02, corresponding to a minimum detectable change of 2 points. The area under the curve at the 1 and 4-week follow-up was 0.72 (0.62, 0.81) and 0.92 (0.86, 0.97), respectively. The minimum clinically important difference at the 1 and 4-week follow-up corresponded to a change of 2.2 and 1.5 points, respectively.

Conclusions: Clinicians can be confident that a 2-point change on the NPRS represents clinically meaningful change that exceeds the bounds of measurement error.

Publication types

  • Evaluation Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cohort Studies
  • Disability Evaluation
  • Female
  • Humans
  • Infant
  • Low Back Pain / diagnosis*
  • Low Back Pain / physiopathology*
  • Low Back Pain / rehabilitation
  • Male
  • Pain Measurement / methods*
  • Physical Therapy Modalities
  • Surveys and Questionnaires