Neck Pain and Disability Scale
The most used neck disability questionnaires are the Neck Pain and Disability scale (NPAD) and the Neck Disability Index (NDI) .
The Neck Pain and Disability scale (NPAD) is a composite index including 20 items which measure the intensity of neck pain and related disability. Until 1999, several measures of generalised pain and disability were available (Oswestry Disability Questionnaire and Pain Disability Index), but there was no well-developed measure that dealt specifically with neck pain. To provide a new measure of neck pain and disability the NPAD has been developed. It was originally developed in the USA by Wheeler and colleagues, but there are various other translations of the scale. Validated French, Turkish, German, Portuguese, Italian, Dutch, English, … translations are available showing adequate validity and reliability. The 20-item scale measures problems with neck movements, neck pain intensity, effect of neck pain on emotion and cognition, and the level of interference with daily life activities. The NPAD is a validated measure to evaluate outcomes in patients with neck pain. It is easy to complete for the patients themselves, and easy to score for the evaluators. Its interference with vocational, recreational, social, and functional aspects of living; and the presence and extent of associated emotional factors.
Cervical pain syndromes.
The NPAD is a 20-item measure that was specifically developed for patients with neck pain.
Blozik E. et al. found that patients who were classified to be depressed (regression coefficient 2.1, p<0.001), anxious (1.9, p<0.001), or having deficits in social support (5.5, p=0.004) scored significantly higher NPAD scores. (level of evidence B)
The NPAD is useful in chronic neck pain and C1-2 fusion patients.
Method of Use
Patients respond to each item by marking along a 10cm visual analog scale (VAS). Item scores range from 0 to 5, and the total score is a total of the item scores (possible range 0 (no pain) – 100 (maximal pain)). The NPAD score is well validated if no more than 15% of the items are missing. Completion of the NPAD usually requires less than 5 minutes.
Martin Scherer et al. found that the German version of the neck pain and disability scale (NPAD-d) has evidence of validity and reliability in a general practice setting.(level of evidence B) The NPAD-d Exhibited stable internal consistency, good construct and discriminant validity. It may be useful in the clinical assessment process and the management of neck pain.
Wim Jorritsma et al. found that the Dutch language version of the NPAD (NPAD-DLV) has a good validity. (level of evidence B)
The stability of a score with repeated measurements over time is defined as test-retest reliability. It is assessed by having an individual complete the instrument 2 or more times during a period when the individual’s condition is expected to remain stable. Intra-class correlation coefficient and SEM values are commonly used to estimate test-retest reliability.
M. Scherer et al. tested reliability using Cronbach’s alpha. He found that the German version of the NPAD demonstrated good reliability in a general practice setting. Chronbach’s alpha of NPAD-d was 0.94. (level of evidence B)
W. Jorritsma et al. found a Cronbach’s alpha of 0.93 for the Dutch version of the NPAD.(level of evidence B)
W. Jorritsma et al. found that the reliability of the NPAD-DLV was acceptable for patients with CNP. The mean test-retest interval was 18.2 days (SD 6.2, range 6-34).
ICC = 0.76 (0.57-0.87)
LOAs (Limits of agreement) = +-20.9 (scale 0-100)
(level of evidence B)
Bremerich et al. found that the Cronbach’s alpha scores for the NPAD-d whole scale and the NPAD-d sub-scales pain disability and neck specific function were 0.97, 0.95, 0.97 and 0.87, respectively. The test-retest reliability of the NPAD-d was excellent (0.97). (level of evidence B)
The Neck Pain and Disability Scale (NPAD) has been translated into several languages. The following versions are well validated: Turkish, French, German, Brazilian, Portuguese, Korean, Italian, Iranian and Dutch version. (level of evidence B)
Content validity: The specific items on the instrument and what they measure determine the evidence that is based on content. The International Classification of Functioning, Disability and Health model can be used to define item content. According to this model, items can potentially measure the domains of (1) body structure and function and (2) activity and participation.
Construct validity: While evidence for content relates directly to what the items measure, evidence for construct validity assesses how the scores on the instrument relate to other measures of the construct.60 A strong relationship between the scores on the instrument and other measures of the same or a related construct provides evidence for convergent validity; little or no relationship between the scores on the instrument and other measures of distinctly different constructs provides evidence for divergent validity.
M. Scherer et al. evaluated the construct validity of the NPAD-d by simple correlation analyses (Pearson’s rho) with social and clinical characteristics.
Item-to-total correlations ranged between 0.414 - 0.829.
Correlation analysis showed high correlations with criterion variables.
W. Jorritsma et al. found that the NPAD-DLV is a valid measure of self-reported neck-pain related disability.
Item-to-total correlations ranged between 0.45 - 0.73.
NPAD-DLV and SF-36 correlation ranged between -0.36 - -0.70.
NPAD-DLV and VASpain correlation was 0.54.
NPAD-DLV and VASdisability correlation was 0.57.
Total scores of NPAD-DLV and NDI-DLV correlation was 0.77.
Bremerich et al. found that the NPAD-d is a valid patient-orientated instrument for use in future studies of Neck Pain And Disability in German speaking patients.
Evidence for responsiveness assesses the ability of the instrument to detect changes in an individual’s status over time. The score on an outcome instrument should increase and decrease if the individual’s condition improves and worsens, respectively.
Bremerich FH, Grob D, Dvorak J, Mannion AF. The Neck Pain and Disability Scale: cross-cultural adaptation into German and evaluation of its psychometric properties in chronic neck pain and C1-2 fusion patients. Spine. 2008;33(9):1018-27.
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- Eva Blozik, Wolfgang Himmel, Michael M. Kochen, Christoph Herrmann-Lingen, Martin Scherer. Sensitivity to change of the Neck Pain and Disability Scale. Spine. 2011;20:882-889. (level of evidence B)
- Martin Scherer, Eva Blozik, Wolfgang Himmel et al. Psychometric properties of a German version of the neck pain and disability scale. Spine. 2008;17:922-929. (level of evidence B)
- Wim Jorritsma, Grietje E. de Vries, Pieter U. Dijkstra et al. Neck Pain and Disability Scale and Neck Disability Index: validity of Dutch language versions. Spine. 2010. (level of evidence B)
- Wim Jorritsma, Grietje E. de Vries, Pieter U. Dijkstra et al. Neck Pain and Disability Scale and Neck Disability Index: reproducibility of Dutch language versions. Spine. 2010. (level of evidence B)
- Bremerich FH, Grob D, Dvorak J, Mannion AF. The Neck Pain and Disability Scale: cross-cultural adaptation into German and evaluation of its psychometric properties in chronic neck pain and C1-2 fusion patients. Spine. 2008;33(9):1018-27. (level of evidence B)
- RobRoy L. Martin. A Survey of Self-reported Outcome Instruments for the Foot and Ankle. Journal of orthopaedic sports physical therapy. 2007.