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RehabMeasures Instrument

Numeric Pain Rating Scale

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Purpose

The NPRS measures the subjective intensity of pain.

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Instrument Details

Acronym NPRS

Area of Assessment

Pain

Assessment Type

Patient Reported Outcomes

Administration Mode

Paper & Pencil

Cost

Free

Diagnosis/Conditions

  • Pain Management

Key Descriptions

  • The NPRS is an 11-point scale from 0-10:
    1) “0” = no pain
    2) “10” = the most intense pain imaginable
  • Patients verbally select a value that is most in line with the intensity of pain that they have experienced in the last 24 hours.
  • A written form is also frequently used with the numeric values of 0 – 10 written out.
  • The NPRS has good sensitivity while producing data that can be statistically analyzed (Williamson & Hoggar, 2005).

Number of Items

1

Time to Administer

Less than 3 minutes

Required Training

No Training

Age Ranges

Adult

18 - 64

years

Elderly Adult

65 +

years

Instrument Reviewers

Initially reviewed by Krista Van Der Laan PT, DPT, OCS; Updated by Rachel Tappan, PT, NCS, Eileen Tseng, PT, DPT, NCS, and the SCI EDGE task force of the Neurology Section of the APTA in 7/2012.

ICF Domain

Body Function

Measurement Domain

Sensory

Professional Association Recommendation

Recommendations for use of the instrument from the Neurology Section of the American Physical Therapy Association’s Multiple Sclerosis Taskforce (MSEDGE), Parkinson’s Taskforce (PD EDGE), Spinal Cord Injury Taskforce (PD EDGE), Stroke Taskforce (StrokEDGE), Traumatic Brain Injury Taskforce (TBI EDGE), and Vestibular Taskforce (Vestibular EDGE) are listed below. These recommendations were developed by a panel of research and clinical experts using a modified Delphi process.

 

For detailed information about how recommendations were made, please visit:  http://www.neuropt.org/go/healthcare-professionals/neurology-section-outcome-measures-recommendations

 

Abbreviations:

 

HR

Highly Recommend

R

Recommend

LS / UR

Reasonable to use, but limited study in target group  / Unable to Recommend

NR

Not Recommended

 

Recommendations for use based on acuity level of the patient:

 

Acute

(CVA < 2 months post)

(SCI < 1 month post) 

(Vestibular < 6 weeks post)

Subacute

(CVA 2 to 6 months)

(SCI 3 to 6 months)

Chronic

(> 6 months)

SCI EDGE

R

R

HR

 

Recommendations based on SCI AIS Classification: 

 

AIS A/B

AIS C/D

SCI EDGE

R

R

  

 

Recommendations for entry-level physical therapy education and use in research:

 

Students should learn to administer this tool? (Y/N)

Students should be exposed to tool? (Y/N)

Appropriate for use in intervention research studies? (Y/N)

Is additional research warranted for this tool (Y/N)

SCI EDGE

Yes

Yes

Yes

Not reported

Considerations

Older Adults: (Herr et al, 2004)

  • Herr et al recommend use of a Verbal Descriptor Scale over the NPRS based on evidence related to failures, internal consistency reliability, construct validity, scale sensitivity, and patient preference. 

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Chronic Pain

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Minimally Clinically Important Difference (MCID)

Chronic Musculoskeletal Pain: (Salaffi et al, 2004; n = 825 patients with chronic musculoskeletal pain)

  • 1 point or 15.0% change

 

Shoulder Pain: (Michener et al., 2011; n = 136; surgical and non-surgical conditions; mean age 51.7(16.4) years; 76.5% no surgery,23.5% status post surgery; assessment of average NPRS scores for at rest, normal activity, and strenuous activity)

  • 2.17 points for surgical and non-surgical subjects after 3-4 weeks of rehabilitation 

 

Chronic Pain: (Farrar et al, 2001; n = 2,724 subjects with varying diagnoses including fibromyalgia, diabetic neuropathy, post-herpetic neuralgia, chronic low back pain and osteoarthritis)

  • 1.7 points or a reduction of 27.9% (raw change/baseline x 100)

Test/Retest Reliability

Chronic Pain: (Jensen & McFarland, 1993; n = 200; mean age = 43.83 (13.2) years; mean time since pain onset = 6.13 (8.24) years)

  • Adequate test-retest reliability for a single pair of assessments (one assessment during week 1, one assessment during week 2) (r = 0.63)
  • Excellent test-retest reliability for ratings on 2 or more days during week 1 compared to 2 or more days during week 2 (r = 0.79 – 0.92)
  • Test-retest reliability increases with increasing numbers of ratings with the highest reliability for 4 ratings/day taken on 7 days (r=0.95)

Interrater/Intrarater Reliability

Chronic Pain: (Jensen & McFarland, 1993)

  • Excellent internal consistency for a single pair of ratings (one during week 1 and one during week2) (Coefficient alpha = 0.84)
  • Excellent internal consistency for ratings on 2 or more days during week 1 compared to 2 or more days during week 2 (Coefficient alpha = 0.89 –0.98)

Responsiveness

Shoulder Pain: (Michener et al., 2011)

  • Large effect size for surgical (ES = 1.51) and non-surgical subjects (ES = 1.94)

Spinal Injuries

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Minimally Clinically Important Difference (MCID)

Chronic SCI: (Hanley et al, 2006a; n = 82; mean age = 41.44 (10.14) years; 54% cervical SCI, 38% thoracic SCI, 7% lumbar/sacral SCI; average pretreatment pain intensity = 5.27 (1.79) on NPRS)

  • 1.80 points or 36%

Cut-Off Scores

Traumatic Spinal Cord Injury (SCI): (Forchhemier MB et al, 2011; n = 6096; mean age = 32.5 (14) years; mean time since injury = 9.8 (9.3) years; all subjects had SCI and pain; injury level: 24.3% AIS D, 5.8% paraplegia AIS C, 5.0% paraplegia B, 29.8% paraplegia A, 7.0% tetraplegia AIS C, 8.0% tetraplegia AIS B, 20.1% tetraplegia AIS A)

  • Pain severity can be categorized into 3 distinct groups as relates to pain interference: 1-3, 4-6, and 7-10 

 

Chronic SCI: (Hanley et al, 2006b; for questions about general pain: n = 307, mean age = 43.1 (13.0) years; for questions about worst pain: n = 174, mean age = 41.6 (13.6) years; inclusion criteria of SCI >6 months)

  • For rating overall pain: mild = 1-3, moderate = 4-7, severe = 8-10 
  • For rating worst pain problem: mild = 1-3, moderate = 4-6, severe = 7-10
  • For cut-off determination, pain severity on NPRS was compared to pain interference

Construct Validity

Convergent Validity:

Traumatic SCI: (Dijkers, 2010; n = 168; mean 38(18) years; level of injury: 10% paraplegia incomplete, 26% paraplegia complete, 45% tetraplegia incomplete, 19% tetraplegia complete)

  • Adequate correlation between NPRS and Verbal Rating Scale (Spearman’s = 0.38)

Content Validity

SCI: (Bryce et al, 2007; n = 50 health care providers attending the 2006 combined American Spinal Injury Association (ASIA)/International Spinal Cord Society (ISCoS) scientific meeting)

  • In a vote on the validity and usefulness of the NPRS in people with pain related to a SCI, attendees voted as follows: 
    • 64% NPRS is a valid measure and should be part of a minimum dataset for clinical trials 
    • 14% NPRS is a valid measure but should be part of an expanded dataset only 
    • 20% NPRS needs further study to establish reliability and validity before being recommended 
    • 2% NPRS is not valid or relevant for use 
    • 79% NPRS as first choice for a minimum data set over a VRS (16%) and VAS (5%) (n= 57)

Non-Specific Patient Population

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Minimally Clinically Important Difference (MCID)

Post-operative Patients: (Sloman et al, 2006; n = 150; mean age = 47.2 years; 56% post-abdominal surgery, 28.6% post-orthopedic surgery, 15.4% other types of surgery) 

  • Percent change in NPRS rather than raw score change may provide more meaningful information regarding a patient’s response to pain treatment. For example, a change from 3/10 pain to 0/10 pain may be more meaningful than a change from 8/10 pain to 5/10 pain. 
  • Therefore, MCIDs were determined in percent change: 
    • 35% reduction on the NPRS had a rating of “minimal relief” 
    • 67% reduction had a rating of “moderate relief” 
    • 70% reduction had a rating of “much relief” 
    • 94% reduction had a rating of “complete relief”

 

Hospital/Emergency Room Population: (Bijur et al, 2003; n = 108; mean age = 44 years; participants presented with acute pain in the emergency room department)

  • 1.3 points

Interrater/Intrarater Reliability

Healthy Populations: (Herr et al, 2004; n = 175 total, 86 subjects aged 25-55 years (mean age = 39.1 (8.8) years), 89 subjects aged 65-94 years (mean age = 76.0 (7.4) years)) 

  • Excellent interrater reliability with 100% agreement between two raters scoring the 0-10 point NPRS

Internal Consistency

Healthy Populations: (Herr et al, 2004)

  • Excellent internal consistency for NPRS in participants aged 65-94 (Cronbach’s alpha = 0.87) 
  • Excellent internal consistency for NPRS in participants aged 25-55 (Cronbach’s alpha = 0.88)

Criterion Validity (Predictive/Concurrent)

Concurrent Validity:

Healthy Populations: (Herr et al, 2004)

  • Excellent correlation between NPRS and Visual Analogue Scale (= 0.86)
  • Excellent correlation between NPRS and Verbal Descriptor Scale (= 0.88)
  • Excellent correlation between NPRS and 21-point Numeric Rating Scale (r = 0.87) 
  • Excellent correlation between NRPS (on 0-20 scale) and Faces Pain Scale (= 0.80)

Construct Validity

Convergent Validity: 

Hospital/Emergency Room Population: (Bijur et al, 2003) 

  • Excellent correlation between NRPS and VAS (= 0.94, 95% CI = 0.93-0.95)

Face Validity

Healthy Population: (Herr et al, 2004)

  • Subjects were shown 5 scales rating pain intensity and asked which scale best described the severity of pain experienced during the study. 
    • 35.3% preferred the 21-point Numeric Rating Scale (written format) 
    • 25.3% preferred the Verbal Descriptor Scale 
    • 15.9% preferred the NPRS (11-point verbal scale) 
    • 12.9% preferred the Faces Pain Scale 
    • 10.6% preferred the Visual Analogue Scale

Responsiveness

Healthy Population: (Herr et al, 2004)

  • NPRS detected significant differences across temperatures of thermal stimuli tested (F6,1037 = 67.09

Brain Injury

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Standard Error of Measurement (SEM)

Lower Back Pain: (Childs et al, 2005; n = 131; mean age = 33.9 (11) years; patients receiving physical therapy; 87% with symptoms for under 6 weeks)

  • SEM = 1.02

Minimal Detectable Change (MDC)

Lower Back Pain: (Childs et al, 2005)

  • 2 points based on a 95% confidence interval

Minimally Clinically Important Difference (MCID)

Lower Back Pain: (Childs et al, 2005)

  • At 1 week of physical therapy treatment = 1.5 points
  • At 4 weeks of physical therapy treatment = 2.2 points

Responsiveness

Lower Back Pain: (Childs et al, 2005)

  • Large effect size at 1 week and 4 weeks (ES = 0.95-1.2) in patients receiving physical therapy for low back pain

Bibliography

Bijur, P. E., Latimer, C. T., et al. (2003). "Validation of a verbally administered numerical rating scale of acute pain for use in the emergency department." Acad Emerg Med 10(4): 390-392. Find it on PubMed

Bryce, T. N., Budh, C. N., et al. (2007). "Pain after spinal cord injury: an evidence-based review for clinical practice and research. Report of the National Institute on Disability and Rehabilitation Research Spinal Cord Injury Measures meeting." J Spinal Cord Med 30(5): 421-440. Find it on PubMed

Childs, J. D., Piva, S. R., et al. (2005). "Responsiveness of the numeric pain rating scale in patients with low back pain." Spine (Phila Pa 1976) 30(11): 1331-1334. Find it on PubMed

Dijkers, M. (2010). "Comparing quantification of pain severity by verbal rating and numeric rating scales." J Spinal Cord Med 33(3): 232-242. Find it on PubMed

Farrar, J. T., Young, J. P., Jr., et al. (2001). "Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale." Pain 94(2): 149-158. Find it on PubMed

Forchheimer, M. B., Richards, J. S., et al. (2011). "Cut point determination in the measurement of pain and its relationship to psychosocial and functional measures after traumatic spinal cord injury: a retrospective model spinal cord injury system analysis." Arch Phys Med Rehabil 92(3): 419-424. Find it on PubMed

Hanley, M. A., Jensen, M. P., et al. (2006). "Clinically significant change in pain intensity ratings in persons with spinal cord injury or amputation." Clin J Pain 22(1): 25-31. Find it on PubMed

Hanley, M. A., Masedo, A., et al. (2006). "Pain interference in persons with spinal cord injury: classification of mild, moderate, and severe pain." J Pain 7(2): 129-133. Find it on PubMed

Herr, K. A., Spratt, K., et al. (2004). "Pain intensity assessment in older adults: use of experimental pain to compare psychometric properties and usability of selected pain scales with younger adults." Clin J Pain 20(4): 207-219. Find it on PubMed

Jensen, M. P. and McFarland, C. A. (1993). "Increasing the reliability and validity of pain intensity measurement in chronic pain patients." Pain 55(2): 195-203. Find it on PubMed

Michener, L. A., Snyder, A. R., et al. (2011). "Responsiveness of the numeric pain rating scale in patients with shoulder pain and the effect of surgical status." J Sport Rehabil 20(1): 115-128. Find it on PubMed

Salaffi, F., Stancati, A., et al. (2004). "Minimal clinically important changes in chronic musculoskeletal pain intensity measured on a numerical rating scale." Eur J Pain 8(4): 283-291. Find it on PubMed

Sloman, R., Wruble, A. W., et al. (2006). "Determination of clinically meaningful levels of pain reduction in patients experiencing acute postoperative pain." Pain Manag Nurs 7(4): 153-158. Find it on PubMed

Stratford, P. W. and Spadoni, G. (2001). "FEATURE ARTICLES-The reliability, consistency, and clinical application of a numeric pain rating scale." Physiotherapy Canada 53(2): 88-91. Find it on PubMed

Williamson, A. and Hoggart, B. (2005). "Pain: a review of three commonly used pain rating scales." J Clin Nurs 14(7): 798-804. Find it on PubMed

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