Factor Structure of the Neck Disability Index

Gabel, Charles Philip; Melloh, Markus; Cuesta-Vargas, Antonio I (2011). Factor Structure of the Neck Disability Index. Spine, 36(21), p. 1815. Hagerstown, Md.: Lippincott Williams & Wilkins 10.1097/BRS.0b013e31822c0521

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BACKGROUND CONTEXT: The Neck Disability Index frequently is used to measure outcomes of the neck. The statistical rigor of the Neck Disability Index has been assessed with conflicting outcomes. To date, Confirmatory Factor Analysis of the Neck Disability Index has not been reported for a suitably large population study. Because the Neck Disability Index is not a condition-specific measure of neck function, initial Confirmatory Factor Analysis should consider problematic neck patients as a homogenous group. PURPOSE: We sought to analyze the factor structure of the Neck Disability Index through Confirmatory Factor Analysis in a symptomatic, homogeneous, neck population, with respect to pooled populations and gender subgroups. STUDY DESIGN: This was a secondary analysis of pooled data. PATIENT SAMPLE: A total of 1,278 symptomatic neck patients (67.5% female, median age 41 years), 803 nonspecific and 475 with whiplash-associated disorder. OUTCOME MEASURES: The Neck Disability Index was used to measure outcomes. METHODS: We analyzed pooled baseline data from six independent studies of patients with neck problems who completed Neck Disability Index questionnaires at baseline. The Confirmatory Factor Analysis was considered in three scenarios: the full sample and separate sexes. Models were compared empirically for best fit. RESULTS: Two-factor models have good psychometric properties across both the pooled and sex subgroups. However, according to these analyses, the one-factor solution is preferable from both a statistical perspective and parsimony. The two-factor model was close to significant for the male subgroup (p<.07) where questions separated into constructs of mental function (pain, reading headaches and concentration) and physical function (personal care, lifting, work, driving, sleep, and recreation). CONCLUSIONS: The Neck Disability Index demonstrated a one-factor structure when analyzed by Confirmatory Factor Analysis in a pooled, homogenous sample of neck problem patients. However, a two-factor model did approach significance for male subjects where questions separated into constructs of mental and physical function. Further investigations in different conditions, subgroup and sex-specific populations are warranted.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute for Evaluative Research into Orthopaedic Surgery

UniBE Contributor:

Melloh, Markus

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0362-2436

Publisher:

Lippincott Williams & Wilkins

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:19

Last Modified:

07 Apr 2014 12:21

Publisher DOI:

10.1097/BRS.0b013e31822c0521

PubMed ID:

24200411

Web of Science ID:

000295318000023

URI:

https://boris.unibe.ch/id/eprint/5917 (FactScience: 210800)

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