Latent variable approach to the measurement of physical disability in rheumatoid arthritis

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Objective. To measure physical disability in rheumatoid arthritis (RA) using a latent variable derived from a generic and a disease-specific self-reported disability instrument and an observer-assessed functional status scale. Methods. Consecutive patients with RA completed the modified Health Assessment Questionnaire (M-HAQ) and the Short Form 36 (SF-36) physical function scale. An observer assigned a Steinbrocker functional classification. We used principal component factor analysis to extract a latent variable from the 3 scales. We used the Bayesian Information Criterion to compare how well the new latent variable and the 3 primary scales fit the criterion standards of current work status; vital status at 6 years; grip strength; walking velocity; the timed-button test; pain; and joint tenderness, swelling, and deformity. Results. Complete data were available for 776 RA patients. The extracted latent variable explained 75% of the variance in the 3 primary scales. On a scale of 0-100, higher scores representing less disability, its mean ± SD was 56. 4 ± 22.5. Correlation between the latent variable and the M-HAQ was -0.87; between the latent variable and SF-36 physical function scale was 0.89, and between the latent variable and Steinbrocker class was -0.85. Multivariate models that included the latent variable had superior fit than did models containing the primary scales for the criteria of current working; death by 6 years; pain; joint tenderness, swelling, or deformity; grip strength; walking velocity; and timed button test. Conclusion. A latent variable derived from the M-HAQ, the SF-36 physical function scale, and the Steinbrocker functional class provides a parsimonious scale to measure physical disability in RA. The fit of the latent variable to comparison standards is equivalent or superior to that of the primary scales.

Original languageEnglish (US)
Pages (from-to)399-407
Number of pages9
JournalArthritis Care and Research
Volume51
Issue number3
StatePublished - Jun 15 2004

Fingerprint

Rheumatoid Arthritis
Hand Strength
Walking
Health
Joints
Pain
Principal Component Analysis
Statistical Factor Analysis
Surveys and Questionnaires

Keywords

  • Disease-specific health measures
  • Factor analysis
  • Generic health measures
  • Outcome assessment
  • Physical disability
  • Rheumatoid arthritis

ASJC Scopus subject areas

  • Rheumatology

Cite this

Latent variable approach to the measurement of physical disability in rheumatoid arthritis. / Escalante, Agustin; Del Rincon, Inmaculada; Cornell, John E.

In: Arthritis Care and Research, Vol. 51, No. 3, 15.06.2004, p. 399-407.

Research output: Contribution to journalArticle

@article{c79915ed1e4243cf9a8ecf3f65e04da7,
title = "Latent variable approach to the measurement of physical disability in rheumatoid arthritis",
abstract = "Objective. To measure physical disability in rheumatoid arthritis (RA) using a latent variable derived from a generic and a disease-specific self-reported disability instrument and an observer-assessed functional status scale. Methods. Consecutive patients with RA completed the modified Health Assessment Questionnaire (M-HAQ) and the Short Form 36 (SF-36) physical function scale. An observer assigned a Steinbrocker functional classification. We used principal component factor analysis to extract a latent variable from the 3 scales. We used the Bayesian Information Criterion to compare how well the new latent variable and the 3 primary scales fit the criterion standards of current work status; vital status at 6 years; grip strength; walking velocity; the timed-button test; pain; and joint tenderness, swelling, and deformity. Results. Complete data were available for 776 RA patients. The extracted latent variable explained 75{\%} of the variance in the 3 primary scales. On a scale of 0-100, higher scores representing less disability, its mean ± SD was 56. 4 ± 22.5. Correlation between the latent variable and the M-HAQ was -0.87; between the latent variable and SF-36 physical function scale was 0.89, and between the latent variable and Steinbrocker class was -0.85. Multivariate models that included the latent variable had superior fit than did models containing the primary scales for the criteria of current working; death by 6 years; pain; joint tenderness, swelling, or deformity; grip strength; walking velocity; and timed button test. Conclusion. A latent variable derived from the M-HAQ, the SF-36 physical function scale, and the Steinbrocker functional class provides a parsimonious scale to measure physical disability in RA. The fit of the latent variable to comparison standards is equivalent or superior to that of the primary scales.",
keywords = "Disease-specific health measures, Factor analysis, Generic health measures, Outcome assessment, Physical disability, Rheumatoid arthritis",
author = "Agustin Escalante and {Del Rincon}, Inmaculada and Cornell, {John E.}",
year = "2004",
month = "6",
day = "15",
language = "English (US)",
volume = "51",
pages = "399--407",
journal = "Arthritis and Rheumatology",
issn = "2326-5191",
publisher = "John Wiley and Sons Ltd",
number = "3",

}

TY - JOUR

T1 - Latent variable approach to the measurement of physical disability in rheumatoid arthritis

AU - Escalante, Agustin

AU - Del Rincon, Inmaculada

AU - Cornell, John E.

PY - 2004/6/15

Y1 - 2004/6/15

N2 - Objective. To measure physical disability in rheumatoid arthritis (RA) using a latent variable derived from a generic and a disease-specific self-reported disability instrument and an observer-assessed functional status scale. Methods. Consecutive patients with RA completed the modified Health Assessment Questionnaire (M-HAQ) and the Short Form 36 (SF-36) physical function scale. An observer assigned a Steinbrocker functional classification. We used principal component factor analysis to extract a latent variable from the 3 scales. We used the Bayesian Information Criterion to compare how well the new latent variable and the 3 primary scales fit the criterion standards of current work status; vital status at 6 years; grip strength; walking velocity; the timed-button test; pain; and joint tenderness, swelling, and deformity. Results. Complete data were available for 776 RA patients. The extracted latent variable explained 75% of the variance in the 3 primary scales. On a scale of 0-100, higher scores representing less disability, its mean ± SD was 56. 4 ± 22.5. Correlation between the latent variable and the M-HAQ was -0.87; between the latent variable and SF-36 physical function scale was 0.89, and between the latent variable and Steinbrocker class was -0.85. Multivariate models that included the latent variable had superior fit than did models containing the primary scales for the criteria of current working; death by 6 years; pain; joint tenderness, swelling, or deformity; grip strength; walking velocity; and timed button test. Conclusion. A latent variable derived from the M-HAQ, the SF-36 physical function scale, and the Steinbrocker functional class provides a parsimonious scale to measure physical disability in RA. The fit of the latent variable to comparison standards is equivalent or superior to that of the primary scales.

AB - Objective. To measure physical disability in rheumatoid arthritis (RA) using a latent variable derived from a generic and a disease-specific self-reported disability instrument and an observer-assessed functional status scale. Methods. Consecutive patients with RA completed the modified Health Assessment Questionnaire (M-HAQ) and the Short Form 36 (SF-36) physical function scale. An observer assigned a Steinbrocker functional classification. We used principal component factor analysis to extract a latent variable from the 3 scales. We used the Bayesian Information Criterion to compare how well the new latent variable and the 3 primary scales fit the criterion standards of current work status; vital status at 6 years; grip strength; walking velocity; the timed-button test; pain; and joint tenderness, swelling, and deformity. Results. Complete data were available for 776 RA patients. The extracted latent variable explained 75% of the variance in the 3 primary scales. On a scale of 0-100, higher scores representing less disability, its mean ± SD was 56. 4 ± 22.5. Correlation between the latent variable and the M-HAQ was -0.87; between the latent variable and SF-36 physical function scale was 0.89, and between the latent variable and Steinbrocker class was -0.85. Multivariate models that included the latent variable had superior fit than did models containing the primary scales for the criteria of current working; death by 6 years; pain; joint tenderness, swelling, or deformity; grip strength; walking velocity; and timed button test. Conclusion. A latent variable derived from the M-HAQ, the SF-36 physical function scale, and the Steinbrocker functional class provides a parsimonious scale to measure physical disability in RA. The fit of the latent variable to comparison standards is equivalent or superior to that of the primary scales.

KW - Disease-specific health measures

KW - Factor analysis

KW - Generic health measures

KW - Outcome assessment

KW - Physical disability

KW - Rheumatoid arthritis

UR - http://www.scopus.com/inward/record.url?scp=2642543388&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=2642543388&partnerID=8YFLogxK

M3 - Article

C2 - 15188325

AN - SCOPUS:2642543388

VL - 51

SP - 399

EP - 407

JO - Arthritis and Rheumatology

JF - Arthritis and Rheumatology

SN - 2326-5191

IS - 3

ER -