The Roland-Morris Disability Questionnaire: one or more dimensions?

Area of Science:

• Rehabilitation Medicine
• Psychometrics
• Orthopedics

Background:

• The Roland-Morris Disability Questionnaire (RMDQ) is widely used for assessing disability in low back pain patients.
• Previous research has yielded conflicting results regarding the RMDQ's dimensionality, with some suggesting unidimensionality and others suggesting multidimensionality.

Purpose of the Study:

• To analyze the structural properties of the RMDQ in a large cohort of low back pain patients.
• To determine whether the RMDQ functions as a unidimensional or multidimensional scale using robust statistical methods.

Main Methods:

• Utilized existing datasets from 2826 patients with non-specific low back pain.
• Employed Rasch analysis to assess item fit and unidimensionality.
• Conducted confirmatory factor analysis (CFA) to evaluate a proposed 3-factor structure.

Main Results:

• Rasch analysis indicated that the RMDQ is unidimensional, with only two items showing minor deviations.
• Confirmatory factor analysis demonstrated a poor fit for a 3-factor model, further supporting unidimensionality.
• The study included a large and representative sample of low back pain patients.

Conclusions:

• The Roland-Morris Disability Questionnaire (RMDQ) should continue to be utilized as a unidimensional measure for assessing disability.
• The findings provide strong evidence supporting the RMDQ's single-construct nature in low back pain populations.