The Neck Disability Index: a study of reliability and validity

Area of Science:

• Orthopedics
• Rehabilitation Medicine
• Pain Management

Background:

• Cervical spine soft tissue injuries cause significant chronic disability.
• Assessing disability, especially in daily living activities affected by neck pain, is challenging due to limited tools.

Purpose of the Study:

• To introduce and validate the Neck Disability Index (NDI), a modified Oswestry Low Back Pain Index questionnaire.
• To evaluate the reliability and validity of the NDI for assessing neck pain-related disability.

Main Methods:

• Developed a 10-item scaled questionnaire (NDI) based on the Oswestry Low Back Pain Index.
• Assessed face validity through peer review and patient feedback.
• Evaluated test-retest reliability (n=17) and internal consistency (n=52) using statistical analysis.
• Assessed concurrent validity by comparing NDI scores with visual analogue scales (n=10) and the McGill Pain Questionnaire (n=30).

Main Results:

• Test-retest reliability showed good statistical significance (Pearson's r = 0.89, p < .05).
• Total index alpha was 0.80, with individual item alpha scores above 0.75, indicating high internal consistency.
• Concurrent validity demonstrated moderate to high correlations (0.60-0.70) with measures of perceived improvement and pain.

Conclusions:

• The Neck Disability Index (NDI) is a reliable and internally consistent measure for disability related to neck pain.
• The NDI shows promising validity for assessing functional limitations in activities of daily living following cervical spine injuries.
• Despite small sample sizes in some analyses, the NDI is a valuable tool for neck pain disability assessment.