Outcome Measure Review – The Neck Disability Index
Submitted by: Jake Tumber, PT
What is the Neck Disability Index used for?
The Neck Disability Index (NDI) was developed in the late 1980’s and published in 1991 to measure self-rated pain and disability in patients with neck pain. It comprises 10 sections, each with a score up to 5, for a total of 50 (1). The original developers suggested the following breakdown of NDI scores (2):
0-4: no disability
5-14: mild disability
15-24: moderate disability
25-34: severe disability
35 or over: complete disability
What population is the NDI appropriate for?
The NDI has demonstrated excellent validity and re-test reliability in both acute and chronic populations, as well as neck pain associated with whiplash-associated disorders (WAD) and cervical radiculopathy (1).
Prognostic capabilities and detecting change over time.
Minimal Detectable Change is considered to be 5 points, with some studies suggesting as many as 10 points for radiculopathy (eg WAD3). The Clinically Important Difference is approximately 7 points. The studies suggest a re-test timeframe of 2 weeks to allow change. There is a floor-ceiling effect with the NDI; for patients who score either 40-50 or 0-10, subsequent change will be difficult to detect. Recent research has suggested that an NDI score of greater than 14.5/50 was one variable suggesting a poor outcome following acute whiplash injury (3).
- MacDermid, JC et al. Measurement Properties of the Neck Disability Index: A Systematic Review. J Orthop Sports Phys Ther 2009;39(5):400-417
- Vernon, HT, Mior, SA. The Neck Disability Index: a study of reliability and validity. J Manip Physiol Ther 1991;14:409-415
- Walton, DM et al. Risk Factors for Persistent Problems Following Acute Whiplash: Update of a Systematic Review and Meta-analysis. J Orthop Sports Phys Ther 2013;43(2):31-43.