Original article
Psychometric Properties of the Neck Disability Index and Numeric Pain Rating Scale in Patients With Mechanical Neck Pain

https://doi.org/10.1016/j.apmr.2007.08.126Get rights and content

Abstract

Cleland JA, Childs JD, Whitman JM. Psychometric properties of the Neck Disability Index and numeric pain rating scale in patients with mechanical neck pain.

Objective

To examine the psychometric properties including test-retest reliability, construct validity, and minimum levels of detectable and clinically important change for the Neck Disability Index (NDI) and the numeric rating scale (NRS) for pain in a cohort of patients with neck pain.

Design

Single-group repeated-measures design.

Setting

Outpatient physical therapy (PT) clinics.

Participants

Patients (N=137) presenting to PT with a primary report of neck pain.

Interventions

Not applicable.

Main Outcome Measures

All patients completed the NDI and the NRS at the baseline examination and at a follow-up. At the time of the follow-up, all patients also completed the global rating of change, which was used to dichotomize patients as improved or stable. Baseline and follow-up scores were used to determine the test-retest reliability, construct validity, and minimal levels of detectable and clinically important change for both the NDI and NRS.

Results

Test-retest reliability was calculated using an intraclass correlation coefficient (ICC) (NDI ICC=.50; 95% confidence interval [CI], .25–.67; NRS ICC=.76; 95% CI, .51–.87). The area under the curve was .83 (95% CI, .75–.90) for the NDI score and .85 (95% CI, .78–.93) for the NRS score for determining between stable and improved patients. Thresholds for the minimum clinically important difference (MCID) for the NDI were 19-percentage points and 1.3 for the NRS.

Conclusions

Both the NDI and NRS exhibit fair to moderate test-retest reliability in patients with mechanical neck pain. Both instruments also showed adequate responsiveness in this patient population. However, the MCID required to be certain that the change in scores has surpassed a level that could be contributed to measurement error for the NDI was twice that which has previously been reported. Therefore the ongoing analyses of the properties of the NDI in a patient population with neck pain are warranted.

Section snippets

Methods

We collected data on consecutive patients presenting to 1 of 5 outpatient orthopedic physical therapy (PT) clinics (Rehabilitation Services of Concord Hospital, Concord, NH; Newton-Wellesley Hospital, Boston, MA; Centennial Physical Therapy, Colorado Springs, CO; Groves Physical Therapy, St Paul, MN; Sharp HealthCare, San Diego, CA) between July 2004 and July 2006 with a primary report of neck pain from 2 clinical trials that were included in the analysis.17, 18 Both studies included identical

Results

Of the 209 consecutive patients with neck pain screened for eligibility, 138 patients satisfied inclusion and exclusion criteria and agreed to participate (mean, 42.5±11.9y). Of the 71 patients that were not included, 21 had a recent history of whiplash, 13 had signs of nerve root compression, 12 presented with contraindications to the interventions, 8 had prior surgery to the cervical or thoracic spine, 2 had signs of central nervous system involvement, 1 had insufficient English skills to

Discussion

It is essential for clinicians to have an understanding of the psychometric properties of measures, including reliability and responsiveness. Instruments should exhibit acceptable reliability and validity prior to being used to guide clinical decision-making. To determine the reliability and validity of self-report measures, it is useful to compare them with a construct that indicates when a true change has occurred.34 Frequently this construct of true change is a patient global rating of

Conclusions

The results of our study indicate that both the NDI and NRS exhibit fair to moderate test-retest reliability. Both instruments also showed adequate responsiveness in this patient population. However, the MDC required to be certain that the change in scores has surpassed a level that could be attibuted to measurement error for the NDI was twice that which has previously been reported in the literature.9, 16 This warrants further investigation. The responsiveness, as well as the MDC and MCID, for

Acknowledgment

None of the funding organizations played any role in the design, conduct, or reporting of the study or in the decision to submit the study for publication.

References (48)

  • G. Guyatt et al.

    Measuring change over time: assessing the usefulness of evaluative instruments

    J Chronic Dis

    (1987)
  • G.H. Guyatt et al.

    A critical look at transition ratings

    J Clin Epidemiol

    (2002)
  • R. Pietrobon et al.

    Standard scales for measurement of functional outcome for cervical pain or dysfunction

    Spine

    (2002)
  • D.E. Beaton et al.

    Looking for important change/differences in studies of responsiveness

    J Rheumatol

    (2001)
  • D. Riddle et al.

    Use of generic versus region-specific functional status measures on patients with cervical spine disorders

    Phys Ther

    (1998)
  • D.U. Jette et al.

    Physical therapy and health outcomes in patients with spinal impairments

    Phys Ther

    (1996)
  • J.E. Bolton

    Sensitivity and specificity of outcome measures in patients with neck pain: detecting clinically significant improvement

    Spine

    (2004)
  • M. Westaway et al.

    The Patient-Specific Functional Scale: validation of its use in persons with neck dysfunction

    J Orthop Sports Phys Ther

    (1998)
  • P.W. Stratford et al.

    Using the Neck Disability Index to make decisions concerning individual patients

    Physiother Can

    (1999)
  • J.L. Hoving et al.

    Manual therapy, physical therapy, or continued care by the general practitioner for patients with neck pain: long-term results from a pragmatic randomized clinical trial

    Clin J Pain

    (2006)
  • E.L. Hurwitz et al.

    A randomized trial of chiropractic manipulation and mobilization for patients with neck pain: clinical outcomes from the UCLA neck-pain study

    Am J Public Health

    (2002)
  • J.L. Hoving et al.

    Manual therapy, physical therapy, or continued care by a general practitioner for patients with neck painA randomized, controlled trial

    Ann Intern Med

    (2002)
  • J. Keating et al.

    Predicting short-term response and non-response to neck strengthening exercise for chronic neck pain

    J Whiplash Relat Disord

    (2005)
  • J.D. Childs et al.

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

    Spine

    (2005)
  • Cited by (493)

    View all citing articles on Scopus

    Supported by the Orthopaedic Section of the American Physical Therapy Association, the American Academy of Orthopaedic Manual Physical Therapists, and Steens Physical USA.

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.

    View full text