Patient-reported outcome measure
NDI
Neck Disability Index
The Neck Disability Index measures how far neck pain restricts ten everyday activities, scoring each section from 0 to 5 for a raw total out of 50, which is commonly doubled and reported as a percentage from 0% (no disability) to 100% (complete disability).
This instrument is not reproduced here
The Neck Disability Index is under copyright and its author operates a permission process for reproduction and commercial use. It is very widely reproduced in guidelines, textbooks and trials, which is often mistaken for it being free — it is not. Written permission should be obtained before reproducing the sections, and that is why they are not reproduced here.
What the NDI score means
NDI scores run from 0 to 100, where a lower score is better. The bands below are conventional reporting categories, not diagnostic cut-offs.
- No disability0–8
Raw score 0–4 of 50. The patient can cope with most activities of daily living without specific treatment beyond advice.
- Mild disability9–28
Raw score 5–14 of 50. Conservative management is usually appropriate.
- Moderate disability29–48
Raw score 15–24 of 50. Pain and difficulty are the main problems; more detailed assessment is warranted.
- Severe disability49–68
Raw score 25–34 of 50. Neck pain impinges on all aspects of daily living and requires active intervention.
- Complete disability69–100
Raw score 35 or more of 50. Either the patient is severely disabled or symptom magnification should be considered.
Clinically important thresholds
A change in score only matters if it exceeds the smallest difference patients actually notice. Every threshold below is reported with the population it was derived in — a threshold quoted without its population is not usable.
| Type | Value | Subscale | Population | Follow-up | Source |
|---|---|---|---|---|---|
| MCID | 7 raw points (14 percentage points) | — | Mechanical neck pain | — | Vernon H 2008 |
| MCID | 7.5 raw points | — | Cervical radiculopathy | — | Young IA 2010 |
| MDC | 5–10 raw points | — | Neck pain, varies by study | — | MacDermid JC 2009 |
| MCID | ~10 percentage points | — | Whiplash-associated disorder | — | MacDermid JC 2009 |
MCID is the smallest change a patient perceives as meaningful. PASS is the score above which patients consider their state acceptable. SCB is a substantial rather than minimal benefit. MDC is the smallest change exceeding measurement error.
How the score is calculated
Stated in full so the calculation can be independently checked, and reproduced by hand if needed.
The NDI is adapted directly from the Oswestry Disability Index. Each of the ten sections offers six statements scored 0 to 5, where 0 is the least and 5 the most disabled response. The sections cover pain intensity, personal care, lifting, reading, headaches, concentration, work, driving, sleeping and recreation. The section scores are summed to give a raw total out of 50. That raw total is reported either directly, or doubled to express it as a percentage from 0 to 100. Because both conventions are in circulation, which one is being reported should always be stated — a raw NDI of 20 and a percentage NDI of 20 describe very different patients.
Missing data
If a section is omitted, the score is expressed as a proportion of the total possible for the sections completed — the same rule the Oswestry uses. At least 9 of the 10 sections should be completed for a reliable score.
Instrument profile
- Developer
- Howard Vernon and Silvano Mior
- Institution
- Canadian Memorial Chiropractic College, Toronto
- First published
- 1991
- Custodian
- Howard Vernon
- Items
- 10
- Response format
- 10 sections, six statements each, scored 0–5
- Score range
- 0 to 100
- Direction
- Lower score = better
- Recall period
- Today
- Completion time
- About 5 minutes
- Age range
- Adults
- Regions
- Spine
- Conditions
- Neck pain, Whiplash-associated disorder, Cervical radiculopathy, Cervical spondylosis, Chronic neck pain
- Procedures
- Anterior cervical discectomy and fusion, Cervical disc replacement, Neck rehabilitation
- Languages
- English, Spanish, German, Dutch, Swedish, Turkish, Chinese, 25+ validated translations
- Test–retest (ICC)
- 0.50–0.98 across studies, most commonly reported around 0.90
- Internal consistency
- Cronbach's alpha 0.70–0.92
- Validity
- The most widely used and most extensively validated neck-specific disability measure, and the reference standard against which newer neck instruments are compared.
- Responsiveness
- Responsive in both conservative and surgical populations. A recurring criticism is that its factor structure is unstable across studies, with some finding a single factor and others two, which complicates subscale-level interpretation.
- Floor effect
- Floor effect in populations with mild neck pain, where a substantial proportion score in the 0–4 range.
Normative values
Reference values from published cohorts, for comparison against the score you calculated.
| Population | Age | Mean | SD |
|---|---|---|---|
| General population without neck complaint | — | Raw 0–4 | — |
| Primary care neck pain at presentation | — | Raw 12–18 | — |
| Pre-operative cervical fusion | — | Raw 22–30 | — |
When to use the NDI
Well suited to
- Neck pain of any cause, where it is the most comparable measure across the literature.
- Cervical spine surgery outcomes, where it is the dominant reported instrument.
- Whiplash-associated disorder, for which it has been specifically validated.
Limitations and poor fits
- Without written permission from the copyright holder, particularly for commercial or web-based use.
- Low back pain, for which the Oswestry is the equivalent instrument — the NDI is an adaptation of it, not a substitute.
- Reporting a raw score and a percentage interchangeably, which is a common and serious source of confusion in the literature.
NDI compared with other instruments
Instruments measuring a related construct, with the practical difference between them.
| Instrument | Items | Range | What it adds |
|---|---|---|---|
| ODI | 10 | 0–100 | The Oswestry Disability Index measures how far low back pain restricts ten everyday activities, scoring each section from 0 to 5 and expressing the total as a percentage from 0% (no disability) to 100% (maximum disability). |
| RMDQ | 24 | 0–24 | The Roland-Morris Disability Questionnaire measures physical disability from low back pain by counting how many of 24 statements a patient agrees with, giving a score from 0 (no disability) to 24 (maximum disability). |
Copyright and permitted use
Published openly because it is the question every clinician and researcher asks before using an instrument, and almost nobody answers it.
The Neck Disability Index is under copyright and its author operates a permission process for reproduction and commercial use. It is very widely reproduced in guidelines, textbooks and trials, which is often mistaken for it being free — it is not. Written permission should be obtained before reproducing the sections, and that is why they are not reproduced here.
References
- Vernon H, Mior S. The Neck Disability Index: a study of reliability and validity. Journal of Manipulative and Physiological Therapeutics. 1991.PMID 1834753
- Vernon H. The Neck Disability Index: state-of-the-art, 1991–2008. Journal of Manipulative and Physiological Therapeutics. 2008.PMID 18803999
- MacDermid JC, Walton DM, Avery S, et al.. Measurement properties of the Neck Disability Index: a systematic review. Journal of Orthopaedic & Sports Physical Therapy. 2009.PMID 19521015
- Young IA, Cleland JA, Michener LA, Brown C. Reliability, construct validity, and responsiveness of the neck disability index, patient-specific functional scale, and numeric pain rating scale in patients with cervical radiculopathy. American Journal of Physical Medicine & Rehabilitation. 2010.PMID 20164782
Editorial status
Not yet reviewedQueued for clinical review by Sam Tuffun, PT, DPT. Sign-off has not taken place — this is a placeholder assignment, not a completed review.