Numeric Pain Rating Scale

Original Editor - Venus Pagare

Top Contributors - Venus Pagare, Tomer Yona, Evan Thomas and Vanessa Rhule

Purpose

The Numeric Pain Rating Scale (NPRS) is a unidimensional measure of pain intensity in adults,[1][2][3] including those with chronic pain due to rheumatic diseases.[3][4]

Content

The NPRS is a segmented numeric version of the visual analog scale (VAS) in which a respondent selects a whole number (0–10 integers) that best reflects the intensity of his/her pain.[3] The common format is a horizontal bar or line. Similar to the VAS, the NPRS is anchored by terms describing pain severity extremes.[5]

Number of Items

Although various iterations exist, the most commonly used is the 11-item NPRS.[6]

Response Options/Scale

The 11-point numeric scale ranges from '0' representing one pain extreme (e.g. “no pain”) to '10' representing the other pain extreme (e.g. “pain as bad as you can imagine” or “worst pain imaginable”).[2][3]

NRS pain.jpg

Recall Period for Items

Recal varies, but respondents are most commonly asked to report pain intensity “in the last 24 hours” or an average pain intensity.[7]

Obtaining the Scale

Available from Partners Against Pain.

Administration

The NPRS can be administered verbally (therefore also by telephone) or graphically for self-completion.[4] As mentioned above, the respondent is asked to indicate the numeric value on the segmented scale that best describes their pain intensity.[5]

Scoring and Interpretation

Scores range from 0-10 points, with higher scores indicating greater pain intensity.[5]

Merits and Demerits

  • The NPRS takes <1 minute to complete
  • The NPRS is easy to administer and score[4][8]
  • Minimal language translation difficulties supports the use of the NPRS across cultures and languages[9]
  • The NPRS is a valid and reliable scale to measure pain intensit [5]
  • Strengths of this measure over the VAS are the ability to be administered both verballyand in writing, as well as its simplicity of scoring[5]
  • One weakness is that the NPRS evaluates only 1 component of the pain experience and  intensity, and therefore does not capture the complexity and idiosyncratic nature of the pain experience or improvements due to symptom fluctuations.

Psychometric Information

Development

To improve discrimination for detecting relatively small changes, an NPRS comprised of numbers along a scale was used in a population of 100 patients with a variety of rheumatic diseases. Variations in pain descriptors used as anchors for end points on the NPRS have been reported in the literature. However, the methodology used to develop these various anchor terms is unknown.[10][11]

Acceptability

Chronic pain patients prefer the NPRS over other measures of pain intensity, including the VAS, due to comprehensibility and ease of completion.[12] However, focus groups of patients with chronic back pain and symptomatic hip and knee osteoarthritis (OA) have found that the NPRS is inadequate in capturing the complexity and idiosyncratic nature of the pain experience or improvements due to symptom fluctuations.[13][14]

Reliability

High test–retest reliability has been observed in both literate and illiterate patients with rheumatoid arthritis (r = 0.96 and 0.95, respectively) before and after medical consultation.[4]

Validity

For construct validity, the NPRS was shown to be highly correlated with the VAS in patients with rheumatic and other chronic pain conditions (pain>6 months): correlations range from 0.86 to 0.95.[4]

Minimal Clinically Important Difference (MCID)

In clinical trials of pregabalin (also known as Lyrica) for diabetic neuropathy, postherpetic neuralgia, chronic low back pain, fibromyalgia, and OA, analyses of the relationships between changes in NPRS scores and patient reports of overall improvement (measured using a standard 7-point patient Global Impression of Change), demonstrated a reduction of 2 points, or 30%, on the NPRS scores to be clinically important.[15] Similar results were found in low back pain patients when changes in NPRS scores were compared to patient improvements in pain after physical therapy using a 15-point Global Rating of Change scale.[16] In another study, the MCID was found to be 2 points in patients with shoulder pain.[17]

References

  1. Childs JD, Piva SR, Fritz JM. Responsiveness of the numeric pain rating scale in patients with low back pain. Spine 2005;30:1331–4.
  2. 2.0 2.1 Jensen MP, McFarland CA. Increasing the reliability and validity of pain intensity measurement in chronic pain patients. Pain 1993;55: 195–203.
  3. 3.0 3.1 3.2 3.3 Rodriguez CS. Pain measurement in the elderly: a review. Pain Manag Nurs 2001;2:38–46
  4. 4.0 4.1 4.2 4.3 4.4 Ferraz MB, Quaresma MR, Aquino LR, Atra E, Tugwell P, Goldsmith CH. Reliability of pain scales in the assessment of literate and illiterate patients with rheumatoid arthritis. J Rheumatol 1990;17:1022–4
  5. 5.0 5.1 5.2 5.3 5.4 HAWKER GA. Measures of Adult Pain. Arthritis Care & Research 2011; 63,S240–S252
  6. Williamson A. Pain: a review of three commonly used pain rating scales. ISSUES IN CLINICAL NURSING 2005; 14: 798–804
  7. Dworkin RH, Turk DC, Farrar JT, Haythornthwaite JA, Jensen MP, Katz NP, et al. Core outcome measures for chronic pain clinical trials: IMMPACT recommendations. Pain 2005;113:9–19.
  8. Jensen MP, Karoly P, O’Riordan EF, Bland F Jr, Burns RS. The subjective experience of acute pain. Clin J Pain 1989;5:153–9
  9. Langley GB, Sheppeard H. The visual analogue scale: its use in pain measurement. Rheumatol Int 1985;5:145–8.
  10. Downie WW, Leatham PA, Rhind VM, Wright V, Branco JA, Anderson JA. Studies with pain rating scales. Ann Rheum Dis 1978;37:378–81.
  11. Jensen MP, Karoly P, Braver S. The measurement of clinical pain intensity: a comparison of six methods. Pain 1986;27:117–26.
  12. De C Williams AC, Davies HT, Chadury Y. Simple pain rating scales hide complex idiosyncratic meanings. Pain 2000;85:457–63
  13. Hawker GA, Davis AM, French MR, Cibere J, Jordan JM, March L, et al. Development and preliminary psychometric testing of a new OA pain measure: an OARSI/OMERACT initiative. Osteoarthritis Cartilage 2008;16:409–14
  14. Hush JM, Refshauge KM, Sullivan G, De Souza L, McAuley JH. Do numerical rating scales and the Roland-Morris Disability Question-naire capture changes that are meaningful to patients with persistent back pain? Clin Rehabil 2010;24:648–57.
  15. Farrar JT, Young JP Jr, LaMoreaux L, Werth JL, Poole RM. Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale. Pain 2001;94:149–58.
  16. Childs JD, Piva SR, Fritz JM. Responsiveness of the numeric pain rating scale in patients with low back pain. Spine 2005;30:1331–4
  17. Michener LA, Snyder AR, Leggin BG. Responsiveness of the numeric pain rating scale in patients with shoulder pain and the effect of surgical status. Journal of sport rehabilitation. 2011 Feb 1;20(1):115.