Assessing and Adjusting for Cross-Cultural Validity of Impairment and Activity Limitation Scales Through Differential Item Functioning Within the Framework of the Rasch Model

Tennant, Alan; Penta, Massimo; Tesio, Luigi; Grimby, Gunnar; Thonnard, Jean Louis; Slade, Anita; Lawton, Gemma; Simone, Anna Maria; Carter, Jane; Lundgren‐Nilsson, Åsa; Tripolski, Maria; Ring, Haim; Biering‐Sørensen, Fin; Marinček, Črt; Burger, Helena; Phillips, Suzanne

doi:10.1097/01.mlr.0000103529.63132.77

Cited by 270 publications

(320 citation statements)

References 41 publications

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“…Note that the same range of country-bias was found for similar items in stroke patients, using a valid standard instrument for generic disability measurement, the Functional Independence Measure (FIMt). 23 Rasch analysis also highlighted some flaws, suggesting a need for further refinement of the scale. These include some items and categories that systematically elicited unexpected responses leading to significant misfit although, on average, the mean item fit across each subscale was satisfactory and it supported the clinical use of its cumulative scores.…”

Section: Discussionmentioning

confidence: 99%

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A multicenter international study on the Spinal Cord Independence Measure, version III: Rasch psychometric validation

et al. 2006

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Background: A third version of the Spinal Cord Independence Measure (SCIM III), made up of three subscales, was formulated following comments by experts from several countries and Rasch analysis performed on the previous version. Objective: To examine the validity, reliability, and usefulness of SCIM III using Rasch analysis. Design: Multicenter cohort study. Setting: Thirteen spinal cord units in six countries from North America, Europe, and the Middle-East. Subjects: 425 patients with spinal cord lesions (SCL). Interventions: SCIM III assessments by professional staff members. Rasch analysis of admission scores. Main outcome measures: SCIM III subscale match between the distribution of item difficulty grades and the patient ability measurements; reliability of patient ability measures; fit of data to Rasch model requirements; unidimensionality of each subscale; hierarchical ordering of categories within items; differential item functioning across classes of patients and across countries. Results: Results supported the compatibility of the SCIM subscales with the stringent Rasch requirements. Average infit mean-square indices were 0.79-1.06; statistically distinct strata of abilities were 3 to 4; most thresholds between adjacent categories were properly ordered; item hierarchy was stable across most of the clinical subgroups and across countries. In a few items, however, misfit or category threshold disordering were found. Conclusions: The scores of each SCIM III subscale appear as a reliable and useful quantitative representation of a specific construct of independence after SCL. This justifies the use of SCIM in clinical research, including cross-cultural trials. The results also suggest that there is merit in further refining the scale.Spinal Cord (2007) 45, 275-291.

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Section: Discussionmentioning

confidence: 99%

“…If this interpretation holds (and misfit results from an impairment-based DIF), a change in SCIM III mobility items or their 'split' into impairment-specific items 23 may be recommended. The same holds for the use of toilet item (at least in its category '5').…”

Section: Discussionmentioning

confidence: 99%

A multicenter international study on the Spinal Cord Independence Measure, version III: Rasch psychometric validation

et al. 2006

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“…This process has been described in more detail in another paper from our group, including the procedure for rescoring the responses. 21 DIF may manifest itself as a constant difference between countries across the trait (Uniform DIF -the main effect), or as a variable difference, where the response function of the two groups cross over (nonuniform DIF -the interaction effect). Both the country factor and the interaction with the class interval might be significant in some cases, as with any ANOVA's main and interaction effects.…”

Section: Rasch Analysismentioning

confidence: 99%

Cross-cultural validity of FIM in spinal cord injury

et al. 2006

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Objective: To analyse cross-culture validity of the Functional Independence Measure (FIMt) in patients with a spinal cord injury using a modern psychometric approach. Settings: A total of 19 rehabilitation facilities from four countries in Europe. Participants: A total of 647 patients at admission, median age 46 years, 69% male. Methods: Data from the FIMt, collected on inpatient admission, was fitted to the Rasch model. A detailed analysis of scoring functions of the seven categories of the FIMt items was undertaken before to testing fit to the model. Categories were rescored where necessary. Fit to the model was assessed initially within country, and then in the pooled data. Analysis of differential item functioning (DIF) was undertaken in the pooled data for each of the FIMt motor and social cognitive scales, respectively. Final fit to the model was tested for breach of local independence by principle components analysis (PCA). Results: The present scoring system for the FIMt motor and cognitive scales, that is a seven category scale, was found to be invalid, necessitating extensive rescoring. Following this, DIF was found in a number of items within the motor scale, requiring a complex solution of splitting items by country to allow for the valid pooling of data. Five country-specific items could not be retained within this solution. The FIM cognitive scale fitted the Rasch model after rescoring, but there was a substantial ceiling effect. Conclusions: Data from the FIMt motor scale for patients with spinal cord injury should not be pooled in its raw form, or compared from country to country. Only after fit to the Rasch model and necessary adjustments could such a comparison be made, but with a loss of clinical important items. The FIM cognitive scale works well following rescoring, and data may be pooled, but many patients were at the maximum score.

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“…Examples of popular DIF detection methods include the Mantel-Haenszel procedure (10), logistic regression (11) and, more recently, approaches based on item response theory (IRT) measurement frameworks. To date, most attention has been given to investigations of DIF associated with age (12,13), sex (12,14,15), language/translations (16 -18), or culture (12,19,20), but few studies have examined disease-related DIF (21). Given the high relevance of work disability in both RA and OA and the potential of the RA-WIS for cross-disease applications, the current objective was to assess for disease-related DIF in this measure and its impact on the comparability of scores between RA and OA at the scale level.…”

Section: Introductionmentioning

confidence: 99%

“…One strategy may be to perform a sensitivity analysis with a DIF-free version of the RA-WIS (i.e., 20 items) to confirm subgroup differences in WI where such biases could be a concern. A second option may be to explore item-splitting approaches to "adjust" for DIF (19,21) in order to establish disease-specific parameters for individual items to facilitate cross-disease comparisons. The increased complexity of scoring the RA-WIS with such an approach, however, is a potential tradeoff that must be considered, especially from the perspective of clinical practicality.…”

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confidence: 99%

Disease‐related differential item functioning in the work instability scale for rheumatoid arthritis: Converging results from three methods

Tang

2011

Arthritis Care & Research

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Objective. The 23-item Work Instability Scale for Rheumatoid Arthritis (RA-WIS) is a promising measure to assess risk for future work disability. Validated in both rheumatoid arthritis (RA) and osteoarthritis (OA), it has high potential for cross-disease applications. Our objective was to examine disease-related differential item functioning (DIF) in the RA-WIS. Methods. Workers with RA (n ‫؍‬ 120) or OA (n ‫؍‬ 130) were recruited from 3 sites and completed a questionnaire consisting of demographic and health-and work-related variables, including the RA-WIS (range 0 -23, where 23 ‫؍‬ highest work instability). Multiple DIF detection methods were applied for comparability: 1) Mantel-Haenszel and Breslow-Day procedures, 2) hierarchical 3-step sequential logistic regression procedure, and 3) a 1-parameter item response theory approach (Rasch analysis). Both tests of significance (chi-square and F tests) and effect size statistics (⌬ MH , ⌬R 2 ) were assessed to confirm items demonstrating uniform or nonuniform DIF. A 2-step purification procedure was applied to establish a DIF-free conditioning variable (total RA-WIS score) for DIF analyses. The resultant impact of disease-related DIF at the scale level was also evaluated. Results. All 3 DIF detection methods converged to reveal 3 RA-WIS items as having significant disease-related uniform DIF. Two items ("difficulty opening doors" and "pressure on hand") were more likely affirmed in RA, while 1 item ("very stiff") was more likely affirmed in OA. Overall, only a marginal impact at the scale level was found due to a small proportion of scale items exhibiting DIF and the bidirectional nature of DIF effects. Conclusion. RA-WIS scores can be directly compared between RA and OA without significant concerns for DIF-related measurement bias.

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Assessing and Adjusting for Cross-Cultural Validity of Impairment and Activity Limitation Scales Through Differential Item Functioning Within the Framework of the Rasch Model

Abstract: Where data are to be pooled for international studies, analysis of DIF by culture is essential. Where DIF is observed, adjustments can be made to allow for cultural differences in outcome measurement.

Cited by 270 publications

References 41 publications

A multicenter international study on the Spinal Cord Independence Measure, version III: Rasch psychometric validation

A multicenter international study on the Spinal Cord Independence Measure, version III: Rasch psychometric validation

Cross-cultural validity of FIM in spinal cord injury

Disease‐related differential item functioning in the work instability scale for rheumatoid arthritis: Converging results from three methods

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