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Application of the health assessment questionnaire disability index to various rheumatic diseases.

van Groen MM, ten Klooster PM, Taal E, van de Laar MA, Glas CA - Qual Life Res (2010)

Bottom Line: The results were analyzed using the generalized partial credit model as an IRT model.It was found that 4 out of 8 item categories of the HAQ-DI displayed substantial differential item functioning (DIF) over the three diseases.Although the HAQ-DI partially functioned differently in the three disease groups, the measurement regarding the disability level of the patients can be made comparable using IRT methods.

View Article: PubMed Central - PubMed

Affiliation: Institute for Behavioral Research, Faculty of Behavioral Sciences, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands.

ABSTRACT

Purpose: To investigate whether the Stanford Health Assessment Questionnaire Disability Index (HAQ-DI) can serve as a generic instrument for measuring disability across different rheumatic diseases and to propose a scoring method based on item response theory (IRT) modeling to support this goal.

Methods: The HAQ-DI was administered to a cross-sectional sample of patients with confirmed rheumatoid arthritis (n = 619), osteoarthritis (n = 125), or gout (n = 102). The results were analyzed using the generalized partial credit model as an IRT model.

Results: It was found that 4 out of 8 item categories of the HAQ-DI displayed substantial differential item functioning (DIF) over the three diseases. Further, it was shown that this DIF could be modeled using an IRT model with disease-specific item parameters, which produces measures that are comparable for the three diseases.

Conclusion: Although the HAQ-DI partially functioned differently in the three disease groups, the measurement regarding the disability level of the patients can be made comparable using IRT methods.

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Related in: MedlinePlus

An illustration of the item difficulty locations (average of the 3 category intersection parameters) of the Health Assessment Questionnaire Disability Index on the IRT latent scale in patients with osteoarthritis and gout
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Fig1: An illustration of the item difficulty locations (average of the 3 category intersection parameters) of the Health Assessment Questionnaire Disability Index on the IRT latent scale in patients with osteoarthritis and gout

Mentions: To clarify the interpretation of the results in the table, the item probabilities for OA and gout are illustrated in Fig. 1. Consider the item Dressing and grooming. The discrimination indices (under the heading αi in Table 3) show that the item has the highest loading on the latent dimension for the patients with gout and the lowest for the patients with OA. Further, in Table 3 and Fig. 1, it can be seen that the category intersection parameters δij are higher for the patients with gout than for the patients with OA. This means that the expected score on Dressing and grooming given a certain disability level is higher for the patients with OA than for the patients with gout. That is, patients with OA endorse this item more and the item Dressing and grooming is more difficult for them than for the patients with gout.Fig. 1


Application of the health assessment questionnaire disability index to various rheumatic diseases.

van Groen MM, ten Klooster PM, Taal E, van de Laar MA, Glas CA - Qual Life Res (2010)

An illustration of the item difficulty locations (average of the 3 category intersection parameters) of the Health Assessment Questionnaire Disability Index on the IRT latent scale in patients with osteoarthritis and gout
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2963741&req=5

Fig1: An illustration of the item difficulty locations (average of the 3 category intersection parameters) of the Health Assessment Questionnaire Disability Index on the IRT latent scale in patients with osteoarthritis and gout
Mentions: To clarify the interpretation of the results in the table, the item probabilities for OA and gout are illustrated in Fig. 1. Consider the item Dressing and grooming. The discrimination indices (under the heading αi in Table 3) show that the item has the highest loading on the latent dimension for the patients with gout and the lowest for the patients with OA. Further, in Table 3 and Fig. 1, it can be seen that the category intersection parameters δij are higher for the patients with gout than for the patients with OA. This means that the expected score on Dressing and grooming given a certain disability level is higher for the patients with OA than for the patients with gout. That is, patients with OA endorse this item more and the item Dressing and grooming is more difficult for them than for the patients with gout.Fig. 1

Bottom Line: The results were analyzed using the generalized partial credit model as an IRT model.It was found that 4 out of 8 item categories of the HAQ-DI displayed substantial differential item functioning (DIF) over the three diseases.Although the HAQ-DI partially functioned differently in the three disease groups, the measurement regarding the disability level of the patients can be made comparable using IRT methods.

View Article: PubMed Central - PubMed

Affiliation: Institute for Behavioral Research, Faculty of Behavioral Sciences, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands.

ABSTRACT

Purpose: To investigate whether the Stanford Health Assessment Questionnaire Disability Index (HAQ-DI) can serve as a generic instrument for measuring disability across different rheumatic diseases and to propose a scoring method based on item response theory (IRT) modeling to support this goal.

Methods: The HAQ-DI was administered to a cross-sectional sample of patients with confirmed rheumatoid arthritis (n = 619), osteoarthritis (n = 125), or gout (n = 102). The results were analyzed using the generalized partial credit model as an IRT model.

Results: It was found that 4 out of 8 item categories of the HAQ-DI displayed substantial differential item functioning (DIF) over the three diseases. Further, it was shown that this DIF could be modeled using an IRT model with disease-specific item parameters, which produces measures that are comparable for the three diseases.

Conclusion: Although the HAQ-DI partially functioned differently in the three disease groups, the measurement regarding the disability level of the patients can be made comparable using IRT methods.

Show MeSH
Related in: MedlinePlus