RESEARCH - Measure of function in RA: individualized or classical scales?

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Ann Rheum Dis. Published Online First: 2 April 2009.

doi:10.1136/ard.2008.102137

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Extended Report

Measure of function in rheumatoid arthritis: individualized or

classical scales?

Raphaèle Seror 1*, Florence Tubach 1, Baron 1, Francis

Guillemin 2 and Philippe Ravaud 1

1 Departement d'Epidemiologie- Groupe Hospitalier Bichat - Claude

Bernard, France

2 Centre d'epidemiologie Clinique CEI6, , France

Abstract

Objective: The Health Assessment Questionnaire Disability Index

(HAQ-DI) is the most widely used measure of function in rheumatoid

arthritis (RA). To enhance the incorporation of patients’ view in

outcome assessment, this study aimed to evaluate individualized forms

of the HAQ-DI.

Patients and methods: HAQ-DI data were prospectively obtained from 370

RA outpatients treated with leflunomide over a 6-month period. At

baseline and final visits, patients had to rate the importance they

attached to each activity addressed by the 20 HAQ-DI items, and to

select the 5 activities they considered the most important. Different

individualized scales were evaluated: scales preserving all domains,

in which the score for each item is multiplied by or added to its

importance; and scales involving for each patient only the 5 most

important items. The psychometric properties of theses scales were

compared to those of the HAQ-DI.

Results: For each HAQ-DI item, severity and importance scores were

weakly correlated. Scores for all individualized scales were highly

correlated with the HAQ-DI score (rho>0.75). All scales had a good

internal consistency (Cronbach’s alpha: 0.87 to 0.88). Compared to the

HAQ-DI, individualized scales did not have better sensitivity to

change (standardized response mean: 0.64 to 0.69 vs. 0.74).

Conclusion Individualized scales have similar properties as the

HAQ-DI. However, individualized questionnaires measuring importance

gave complementary information to the measure of disability.

Therefore, even if individualization is probably not needed for group

assessment in all randomized controlled trials, the use of

individualized questionnaires could be clinically relevant for

individual RA patients.

http://ard.bmj.com/cgi/content/abstract/ard.2008.102137v1?papetoc

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