Upper-Extremity and Mobility Subdomains From the Patient-Reported Outcomes Measurement Information System (PROMIS) Adult Physical Functioning Item Bank

Objective

To create upper-extremity and mobility subdomain scores from the Patient-Reported Outcomes Measurement Information System (PROMIS) physical functioning adult item bank.

Design

Expert reviews were used to identify upper-extremity and mobility items from the PROMIS item bank. Psychometric analyses were conducted to assess empirical support for scoring upper-extremity and mobility subdomains.

Setting

Data were collected from the U.S. general population and multiple disease groups via self-administered surveys.

Participants

The sample (N=21,773) included 21,133 English-speaking adults who participated in the PROMIS wave 1 data collection and 640 Spanish-speaking Latino adults recruited separately.

Interventions

Not applicable.

Main Outcome Measures

We used English- and Spanish-language data and existing PROMIS item parameters for the physical functioning item bank to estimate upper-extremity and mobility scores. In addition, we fit graded response models to calibrate the upper-extremity items and mobility items separately, compare separate to combined calibrations, and produce subdomain scores.

Results

After eliminating items because of local dependency, 16 items remained to assess upper extremity and 17 items to assess mobility. The estimated correlation between upper extremity and mobility was .59 using existing PROMIS physical functioning item parameters (r=.60 using parameters calibrated separately for upper-extremity and mobility items).

Conclusions

Upper-extremity and mobility subdomains shared about 35% of the variance in common, and produced comparable scores whether calibrated separately or together. The identification of the subset of items tapping these 2 aspects of physical functioning and scored using the existing PROMIS parameters provides the option of scoring these subdomains in addition to the overall physical functioning score.     

Measurement Properties of the Spinal Cord Injury-Functional Index (SCI-FI) Short Forms

Objective

To evaluate the psychometric properties of the Spinal Cord Injury-Functional Index (SCI-FI) short forms (basic mobility, self-care, fine motor, ambulation, manual wheelchair, and power wheelchair) based on internal consistency; correlations between short forms banks, full item bank forms, and a 10-item computer adaptive test version; magnitude of ceiling and floor effects; and test information functions.

Design

Cross-sectional cohort study.

Setting

Six rehabilitation hospitals in the United States.

Participants

Individuals with traumatic spinal cord injury (N=855) recruited from 6 national Spinal Cord Injury Model Systems facilities.

Interventions

Not applicable.

Main Outcome Measures

SCI-FI full item bank, 10-item computer adaptive test, and parallel short form scores.

Results

The SCI-FI short forms (with separate versions for individuals with paraplegia and tetraplegia) demonstrate very good internal consistency, group-level reliability, excellent correlations between short forms and scores based on the total item bank, and minimal ceiling and floor effects (except ceiling effects for persons with paraplegia on self-care, fine motor, and power wheelchair ability and floor effects for persons with tetraplegia on self-care, fine motor, and manual wheelchair ability). The test information functions are acceptable across the range of scores where most persons in the sample performed.

Conclusions

Clinicians and researchers should consider the SCI-FI short forms when computer adaptive testing is not feasible.     

Development of a Computer-Adaptive Physical Function Instrument for Social Security Administration Disability Determination

Objectives

To develop and test an instrument to assess physical function for Social Security Administration (SSA) disability programs, the SSA-Physical Function (SSA-PF) instrument. Item response theory (IRT) analyses were used to (1) create a calibrated item bank for each of the factors identified in prior factor analyses, (2) assess the fit of the items within each scale, (3) develop separate computer-adaptive testing (CAT) instruments for each scale, and (4) conduct initial psychometric testing.

Design

Cross-sectional data collection; IRT analyses; CAT simulation.

Setting

Telephone and Internet survey.

Participants

Two samples: SSA claimants (n=1017) and adults from the U.S. general population (n=999).

Interventions

None.

Main Outcome Measures

Model fit statistics, correlation, and reliability coefficients.

Results

IRT analyses resulted in 5 unidimensional SSA-PF scales: Changing & Maintaining Body Position, Whole Body Mobility, Upper Body Function, Upper Extremity Fine Motor, and Wheelchair Mobility for a total of 102 items. High CAT accuracy was demonstrated by strong correlations between simulated CAT scores and those from the full item banks. On comparing the simulated CATs with the full item banks, very little loss of reliability or precision was noted, except at the lower and upper ranges of each scale. No difference in response patterns by age or sex was noted. The distributions of claimant scores were shifted to the lower end of each scale compared with those of a sample of U.S. adults.

Conclusions

The SSA-PF instrument contributes important new methodology for measuring the physical function of adults applying to the SSA disability programs. Initial evaluation revealed that the SSA-PF instrument achieved considerable breadth of coverage in each content domain and demonstrated noteworthy psychometric properties.     

Scale Refinement and Initial Evaluation of a Behavioral Health Function Measurement Tool for Work Disability Evaluation

Objective

To use item response theory (IRT) data simulations to construct and perform initial psychometric testing of a newly developed instrument, the Social Security Administration Behavioral Health Function (SSA-BH) instrument, that aims to assess behavioral health functioning relevant to the context of work.

Design

Cross-sectional survey followed by IRT calibration data simulations.

Setting

Community.

Participants

Sample of individuals applying for Social Security Administration disability benefits: claimants (n=1015) and a normative comparative sample of U.S. adults (n=1000).

Interventions

None.

Main Outcome Measure

SSA-BH measurement instrument.

Results

IRT analyses supported the unidimensionality of 4 SSA-BH scales: mood and emotions (35 items), self-efficacy (23 items), social interactions (6 items), and behavioral control (15 items). All SSA-BH scales demonstrated strong psychometric properties including reliability, accuracy, and breadth of coverage. High correlations of the simulated 5- or 10-item computer adaptive tests with the full item bank indicated robust ability of the computer adaptive testing approach to comprehensively characterize behavioral health function along 4 distinct dimensions.

Conclusions

Initial testing and evaluation of the SSA-BH instrument demonstrated good accuracy, reliability, and content coverage along all 4 scales. Behavioral function profiles of Social Security Administration claimants were generated and compared with age- and sex-matched norms along 4 scales: mood and emotions, behavioral control, social interactions, and self-efficacy. Using the computer adaptive test-based approach offers the ability to collect standardized, comprehensive functional information about claimants in an efficient way, which may prove useful in the context of the Social Security Administration's work disability programs.     

Correspondence Between the RAND–Negative Impact of Asthma on Quality of Life Item Bank and the Marks Asthma Quality of Life Questionnaire

Background

In many research and clinical settings in which patient-reported outcome (PRO) measures are used, it is often desirable to link scores across disparate measures or to use scores from 1 measure to describe scores on a separate measure. However, PRO measures are scored by using a variety of metrics, making such comparisons difficult.

Objective

The objective of this article was to provide an example of how to transform scores across disparate measures (the Marks Asthma Quality of Life Questionnaire [AQLQ-Marks] and the newly developed RAND–Negative Impact of Asthma on Quality of Life item bank [RAND-IAQL-Bank]) by using an item response theory (IRT)-based linking method.

Methods

Our sample of adults with asthma (N = 2032) completed 2 measures of asthma-specific quality of life: the AQLQ-Marks and the RAND-IAQL-Bank. We use IRT-based co-calibration of the 2 measures to provide a linkage, or a common metric, between the 2 measures. Co-calibration refers to the process of using IRT to estimate item parameters that describe the responses to the scales’ items according to a common metric; in this case, a normal distribution transformed to a T scale with a mean of 50 and an SD of 10.

Results

Respondents had an average age of 43 (15), were 60% female, and predominantly non-Hispanic White (56%), with 19% African American, 14% Hispanic, and 11% Asian. Most had at least some college education (83%), and 90% had experienced an asthma attack during the last 12 months. Our results indicate that the AQLQ-Marks and RAND-IAQL-Bank scales measured highly similar constructs and were sufficiently unidimensional for IRT co-calibration. Once linked, scores from the 2 measures were invariant across subgroups. A crosswalk is provided that allows researchers and clinicians using AQLQ-Marks to crosswalk to the RAND-IAQL toolkit.

Conclusions

The ability to translate scores from the RAND-IAQL toolkit to other “legacy” (ie, commonly used) measures increases the value of the new toolkit, aids in interpretation, and will hopefully facilitate adoption by asthma researchers and clinicians. More generally, the techniques we illustrate can be applied to other newly developed or existing measures in the PRO research field to obtain crosswalks with widely used traditional legacy instruments.     

Towards the Development of Clinical Measures for Spinal Cord Injury Based on the International Classification of Functioning,Disability and Health With Rasch Analyses

Objectives

To determine whether the International Classification of Functioning, Disability and Health (ICF) categories relevant to spinal cord injury (SCI) can be integrated in clinical measures and to obtain insights to guide their future operationalization. Specific aims are to find out whether the ICF categories relevant to SCI fit a Rasch model taking into consideration the dimensionality found in previous investigations, local item dependencies, or differential item functioning.

Design

All second-level ICF categories collected in the Development of ICF Core Sets for SCI project in specialized centers within 15 countries from 2006 through 2008.

Setting

Secondary data analysis.

Participants

Adults (N=1048) with SCI from the early postacute and long-term living context.

Interventions

Not applicable.

Main Outcome Measures

Two unidimensional Rasch analyses: one for the ICF categories from body functions and body structures components and another for the ICF categories from the activities and participation component.

Results

Results support good reliability and targeting of the ICF categories in both dimensions. In each dimension, few ICF categories were subject to misfit. Local item dependency was observed between ICF categories of the same chapters. Group effects for age and sex were observed only to a small extent.

Conclusions

The validity of ICF categories to develop measures of functioning in SCI for clinical practice and research is to some extent supported. Model adjustments were suggested to further improve their operationalization and psychometrics.     

Sensitivity of the SCI-FI/AT in Individuals With Traumatic Spinal Cord Injury

Objective

To examine the ability of the Spinal Cord Injury-Functional Index/Assistive Technology (SCI-FI/AT) measure to detect change in persons with spinal cord injury (SCI).

Development of a Self-Report Physical Function Instrument for Disability Assessment: Item Pool Construction and Factor Analysis

Objectives

To build a comprehensive item pool representing work-relevant physical functioning and to test the factor structure of the item pool. These developmental steps represent initial outcomes of a broader project to develop instruments for the assessment of function within the context of Social Security Administration (SSA) disability programs.

Design

Comprehensive literature review; gap analysis; item generation with expert panel input; stakeholder interviews; cognitive interviews; cross-sectional survey administration; and exploratory and confirmatory factor analyses to assess item pool structure.

Setting

In-person and semistructured interviews and Internet and telephone surveys.

Participants

Sample of SSA claimants (n=1017) and a normative sample of adults from the U.S. general population (n=999).

Interventions

Not applicable.

Main Outcome Measure

Model fit statistics.

Results

The final item pool consisted of 139 items. Within the claimant sample, 58.7% were white; 31.8% were black; 46.6% were women; and the mean age was 49.7 years. Initial factor analyses revealed a 4-factor solution, which included more items and allowed separate characterization of: (1) changing and maintaining body position, (2) whole body mobility, (3) upper body function, and (4) upper extremity fine motor. The final 4-factor model included 91 items. Confirmatory factor analyses for the 4-factor models for the claimant and the normative samples demonstrated very good fit. Fit statistics for claimant and normative samples, respectively, were: Comparative Fit Index=.93 and .98; Tucker-Lewis Index=.92 and .98; and root mean square error approximation=.05 and .04.

Conclusions

The factor structure of the physical function item pool closely resembled the hypothesized content model. The 4 scales relevant to work activities offer promise for providing reliable information about claimant physical functioning relevant to work disability.     

Association of Internet Use and Depression Among the Spinal Cord Injury Population

Objective

To examine the relation between the frequency of Internet use and depression among people with spinal cord injury (SCI).

Design

Cross-sectional survey.

Setting

SCI Model Systems.

Participants

People with SCI (N=4618) who were interviewed between 2004 and 2010.

Interventions

Not applicable.

Main Outcome Measures

The frequency of Internet use and the severity of depressive symptoms were measured simultaneously by interview. Internet use was reported as daily, weekly, monthly, or none. The depressive symptoms were measured by the Patient Health Questionnaire-9 (PHQ-9), with 2 published criteria being used to screen for depressive disorder. The diagnostic method places more weight on nonsomatic items (ie, items 1, 2, and 9), and the cut-off method that determines depression by a (PHQ-9) score ≥10 places more weight on somatic factors. The average scores of somatic and nonsomatic items represented the severity of somatic and nonsomatic symptoms, respectively.

Results

Our multivariate logistic regression model indicated that daily Internet users were less likely to have depressive symptoms (odds ratio=.77; 95% confidence interval, .64–.93), if the diagnostic method was used. The linear multivariate regression analysis indicated that daily and weekly Internet usage were associated with fewer nonsomatic symptoms; no significant association was observed between daily or weekly Internet usage and somatic symptoms.

Conclusions

People with SCI who used the Internet daily were less likely to have depressive symptoms.     

Linking the Spinal Cord Injury–Functional Index (SCI-FI) to the PROMIS Physical Functioning Item Bank

ObjectiveTo link 3 Spinal Cord Injury–Functional Index (SCI-FI) item banks (Basic Mobility, Fine Motor Function, Self-Care) to the Patient-Reported Outcome Measurement Information System (PROMIS) Physical Function (PF) metric.DesignObservational studySettingSix SCI Model Systems rehabilitation hospitals in the United States.ParticipantsAdults with SCI (n=855) and healthy individuals (n=730) (N=1585).InterventionsNot applicable.Main Outcome MeasuresThree SCI-FI item banks (Basic Mobility, Fine Motor Function, Self-Care), PROMIS PF v1.0 item bank.ResultsSCI-FI item banks (including 30 items from the PROMIS PF item bank) were administered to 855 adults with SCI as part of the original SCI-FI development study. The data were used to attempt to link 3 SCI-FI banks to the PROMIS PF metric via 2 item-response theory methods: fixed-parameter calibration and separate calibration. Sixteen items common to SCI-FI and PROMIS and verified as free of differential item functioning were used as anchor items to implement the methods. Of the 3 banks, only SCI-FI Basic Mobility could be linked with sufficient precision to PROMIS PF. Comparisons of actual vs linked PROMIS PF scores and test characteristic curves suggested the fixed-parameter method provided slightly more precision than the separate calibration method.ConclusionsThe linkage between PROMIS PF and SCI-FI Basic Mobility was considered satisfactory for group-level usage. Score equivalents computed from SCI-FI Basic Mobility will be useful for researchers comparing functional levels in SCI to those observed in other clinical and nonclinical groups (eg, in comparative effectiveness research).     

Functional Outcomes in Traumatic Disorders of Consciousness: 5-Year Outcomes From the National Institute on Disability and Rehabilitation Research Traumatic Brain Injury Model Systems

Objective

To characterize the 5-year outcomes of patients with traumatic brain injury (TBI) not following commands when admitted to acute inpatient rehabilitation.

Design

Secondary analysis of prospectively collected data from the National Institute on Disability and Rehabilitation Research–funded Traumatic Brain Injury Model Systems (TBIMS).

Setting

Inpatient rehabilitation hospitals participating in the TBIMS program.

Participants

Patients (N=108) with TBI not following commands at admission to acute inpatient rehabilitation were divided into 2 groups (early recovery: followed commands before discharge [n=72]; late recovery: did not follow commands before discharge [n=36]).

Interventions

Not applicable.

Main Outcome Measures

FIM items.

Results

For the early recovery group, depending on the FIM item, 8% to 21% of patients were functioning independently at discharge, increasing to 56% to 85% by 5 years postinjury. The proportion functioning independently increased from discharge to 1 year, 1 to 2 years, and 2 to 5 years. In the late recovery group, depending on the FIM item, 19% to 36% of patients were functioning independently by 5 years postinjury. The proportion of independent patients increased significantly from discharge to 1 year and from 1 to 2 years, but not from 2 to 5 years.

Conclusions

Substantial proportions of patients admitted to acute inpatient rehabilitation before following commands recover independent functioning over as long as 5 years, particularly if they begin to follow commands before hospital discharge.     

Psychometric Properties of the Disorders of Consciousness Scale

Objective

To provide evidence for psychometric properties of the Disorders of Consciousness Scale (DOCS).

Design

Prospective observational cohort.

Settings

Seven rehabilitation facilities.

Participants

Patients (N=174) with severe brain injury.

Interventions

Not applicable.

Main Outcome Measure

DOCS.

Results

Initial analyses suggested eliminating 6 items to maximize psychometrics, resulting in the DOCS-25. The 25 items form a unidimensional hierarchy, rating scale categories are ordered, there are no misfitting items, and differential item functioning was not found according to sex, type of brain injury, veteran status, and days from onset. Person separation reliability (.91) indicates that the DOCS-25 is appropriate for individual patient measurement. Items are well targeted to the sample, with the difference between mean person and item calibrations less than 1 logit. DOCS-25 Rasch measures result in a 62% gain in relative precision over total raw scores. Internal consistency is very good (Cronbach α=.86); interrater agreement is excellent (intracIass correlation coefficient=.90) for both the DOCS-25 and the sensory subscales. The DOCS-25 total measure, but not subscale measures, correlates with the Glasgow Coma Scale and the Coma/Near-Coma Scales and distinguishes significantly between vegetative and minimally conscious states, indicating concurrent validity.

Conclusions

The DOCS-25 is psychometrically strong. It has excellent measurement precision and captures a broad range of patient function, which is critical for capturing recovery of consciousness. The sensory subscales are clinically informative but should not be reported as separate measures. The Keyform synthesizes clinical observations to visualize response patterns with potential for informing clinical decision-making. Future studies should determine sensitivity to change, examine issues of rater severity, and explore the usefulness of the Keyform in clinical practice.     

Comparison of the Utrecht Scale for Evaluation of Rehabilitation-Participation With the ICF Measure of Participation and Activities Screener and the WHO Disability Assessment Schedule II in Persons With Spinal Cord Injury

Objective

To validate the Utrecht Scale for Evaluation of Rehabilitation-Participation (USER-Participation) in persons with spinal cord injury (SCI) using 2 International Classification of Functioning, Disability and Health (ICF)-based instruments: the ICF Measure of Participation and Activities-Screener (IMPACT-S) and the World Health Organization Disability Assessment Schedule II (WHODAS II).

Design

Validation study. Score distributions, internal consistency, and concurrent and discriminant validity were evaluated.

Setting

The community.

Participants

Convenience sample of persons (N=157) with long-term SCI living in The Netherlands.

Interventions

Not applicable.

Main Outcome Measures

USER-Participation, IMPACT-S, and WHODAS II.

Results

No instruments showed floor effects, and 3 out of 6 WHODAS II domains showed ceiling effects. Most scores showed adequate internal consistency (α≥.70), except for the USER-Participation frequency scale (.51) and 2 WHODAS II domains (.58–.60). Spearman correlation coefficients between the segregate USER-Participation scales were <.60 (range, .39–.46), showing that they cover separate aspects of participation. Concurrent validity of the USER-Participation was shown because >75% (83.3%) of the 24 hypotheses (Spearman correlation coefficients above or below .60) with the other measurement instruments were confirmed. Concurrent validity between the IMPACT-S and WHODAS II was not shown (53.8% of 13 hypotheses confirmed). All scores except 4 WHODAS II domains showed significant differences in participation between persons with paraplegia and tetraplegia.

Conclusions

The USER-Participation showed generally satisfactory psychometric properties in Dutch persons with long-term SCI living in the community. The IMPACT-S showed the best psychometric properties, and the WHODAS II showed less favorable results. Future research on the USER-Participation should focus on validation in other languages and different diagnostic groups.     

Item-Level Assessment of the Irritable Bowel Syndrome Quality of Life Questionnaire in Patients With Diarrheal Irritable Bowel Syndrome

Background

In previous studies, the Irritable Bowel Syndrome Quality of Life (IBS-QOL) instrument has been determined to have good measurement properties for general irritable bowel syndrome (IBS) and the diarrheal IBS (IBS-d) subtype in clinical trials.

Objective

This article aims to extend the true-score analyses that have been previously conducted to evaluate the IBS-QOL in IBS-d patients.

Methods

Item response theory analysis was conducted by fitting models to responses from 753 patients with severe IBS-d from a recent clinical trial. Three item response theory models, the constrained graded response model (CGRM), the unconstrained GRM (UGRM), and the testlet response model (TRM), were fit to the 34 items of the IBS-QOL questionnaire. Subsequently, differential item functioning (DIF) for patient sex was assessed by fitting nested models by applying likelihood ratio tests. Model latent trait estimates were then compared with the IBS-QOL score and the IBS Symptom Severity Score.

Results

Model fits improved with complexity, with the TRM model fitting best compared with the CGRM and UGRM. The DIF evaluation for patient sex flagged 17 items for the CGRM and 9 items for the UGRM; however, these items were not found to have much effect on the overall estimation of the latent trait. Differential testlet functioning was not indicated, and no items exhibited potential DIF under the TRM because likelihood ratio tests were not statistically significant. Comparison of latent trait estimates to the IBS Symptom Severity Score and IBS-QOL questionnaire revealed high Spearman correlations (0.47 and ≥0.99, respectively).

Conclusion

Previous true-score approach results were supported by the IBS-QOL item-level analysis. Further, the IBS-QOL total score was found to be a valid measure of perceived quality of life for IBS-d patients when compared with more sophisticated model-based estimates of perceived quality of life. ClinicalTrials.gov identifier: NCT01130272.     

Development of an Instrument to Measure Behavioral Health Function for Work Disability: Item Pool Construction and Factor Analysis

Objectives

To develop a broad set of claimant-reported items to assess behavioral health functioning relevant to the Social Security disability determination processes, and to evaluate the underlying structure of behavioral health functioning for use in development of a new functional assessment instrument.

Design

Cross-sectional.

Setting

Community.

Participants

Item pools of behavioral health functioning were developed, refined, and field tested in a sample of persons applying for Social Security disability benefits (N=1015) who reported difficulties working because of mental or both mental and physical conditions.

Interventions

None.

Main Outcome Measure

Social Security Administration Behavioral Health (SSA-BH) measurement instrument.

Results

Confirmatory factor analysis (CFA) specified that a 4-factor model (self-efficacy, mood and emotions, behavioral control, social interactions) had the optimal fit with the data and was also consistent with our hypothesized conceptual framework for characterizing behavioral health functioning. When the items within each of the 4 scales were tested in CFA, the fit statistics indicated adequate support for characterizing behavioral health as a unidimensional construct along these 4 distinct scales of function.

Conclusions

This work represents a significant advance both conceptually and psychometrically in assessment methodologies for work-related behavioral health. The measurement of behavioral health functioning relevant to the context of work requires the assessment of multiple dimensions of behavioral health functioning. Specifically, we identified a 4-factor model solution that represented key domains of work-related behavioral health functioning. These results guided the development and scale formation of a new SSA-BH instrument.     

Patient-reported outcome measures for chronic wounds with particular reference to pressure ulcer research: A systematic review

Objectives

Pressure ulcers are a major health problem, affect patient psychological, physical and social functioning, and cause significant treatment burden. For comprehensive assessment of the benefits of an intervention, patient-reported evidence of the impact of an intervention on important patient outcomes should be made. We systematically reviewed the quality of life literature on chronic wounds to determine the suitability of generic and chronic wound-specific outcome measures for use in evaluating patient outcomes in pressure ulcer research.

Design

A systematic review of the literature.

Data sources

Searches of eight electronic databases from inception until May 2012 were undertaken.

Review methods

Quality of life domains, item content and content relevance were determined for identified outcome measures. The content validity of identified measures was assessed against an empirically derived pressure ulcer-specific conceptual framework.

Results

Three generic and 14 chronic wound measures were identified but no pressure ulcer-specific measures. None of the existing measures cover all quality of life domains important in pressure ulcers. One condition-specific measure, the Venous Leg Ulcer Measure, matched most closely conceptually, but failed to represent three important domains and contained items not specific to pressure ulcers.

Conclusions

Currently, outcomes important in pressure ulcers are inadequately covered by generic and chronic wound-specific instruments despite similar conceptual models. Highlighted is the need for clear conceptualisation of content as well as determining appropriateness when selecting outcome measures in the future.     

A Concordance Table to Convert FIM Basic Mobility and Self-Care Scale Scores to SCI-FI/AT Scores

ObjectiveTo estimate Spinal Cord Injury Functional Index Assistive Technology (SCI-FI/AT) scores from FIM motor items.DesignSecondary data analysis.SettingFourteen Spinal Cord Injury Model Systems (SCIMS) programs.ParticipantsPersons with traumatic spinal cord injury (SCI) discharged from inpatient rehabilitation at 14 SCIMS programs (N=1237).InterventionsNot applicable.Main Outcome MeasuresFIM motor items were matched to SCI-FI/AT domains and summary scores for each measure were developed. The kernel-based method was employed to develop a concordance table to estimate SCI-FI/AT domain summary scores from content-matched FIM motor item summary scores. We conducted analyses to compare agreement between actual SCI-FI/AT summary scores (actual SCI-FI/AT_S) and estimated SCI-FI/AT summary scores (est-SCI-FI/AT_S) for the total sample and for participants with different SCI injury categories.ResultsNine FIM items matched SCI-FI/AT basic mobility and self-care domain content. Pearson correlations for actual and est-SCI-FI/AT_S scores (0.79) were adequate for using concordance linking methods. Intraclass correlation coefficient values (0.79; 95% confidence interval, 0.77-0.81) indicated moderate reliability. t tests revealed no significant differences between actual and est-SCI-FI/AT_S scores in the total sample. For almost 60% of the sample, actual and est-SCI-FI/AT_S score differences were <5 points (half of a SD). Greater differences between actual and est-SCI-FI/AT_S scores were noted for persons with tetraplegia American Spinal Injury Association Impairment Scales (AISs) A, B, and C.ConclusionsDespite differences between the FIM and SCI-FI/AT assessments, we developed a concordance table to estimate self-care and basic mobility SCI-FI/AT scores from content-matched FIM motor item scores. This concordance table allows researchers to merge FIM data with SCI-FI/AT data to analyze SCI functional outcomes at the group level. However, owing to greater differences between actual and estimated scores, the concordance table should be used with caution to interpret scores for those with cervical-level injuries AISs A, B, C.     

Differential Performance of SF-36 Items in Healthy Adults With and Without Functional Limitations

Horner-Johnson W, Krahn GL, Suzuki R, Peterson JJ, Roid G, Hall T, the RRTC Expert Panel on Health Measurement. Differential performance of SF-36 items in healthy adults with and without functional limitations.

Objective

To determine whether Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) items show differential item functioning among healthy adults with various types of functional limitations as compared with a healthy sample with no identified limitations.

Design

Survey responses were analyzed by using partial correlations.

Setting

General community.

Participants

Participants (N=206) included (1) adults with spinal cord injury (SCI), (2) adults who were deaf or hard of hearing, (3) adults who were legally blind, (4) adults with psychiatric or emotional conditions, and (5) adults with no reported functional limitations. Participants were screened to ensure the absence of substantial health problems.

Interventions

Not applicable.

Main Outcome Measure

SF-36.

Results

Partial correlations showed a significant negative correlation, indicating differential item functioning (ie, apparent bias) for people with SCI on all 10 SF-36 Physical Functioning items. For people who were blind, 5 items showed a significant negative correlation. Two items had significant negative correlations for the deaf/hard-of-hearing group. One item showed significant negative performance for people with mental health conditions.

Conclusions

Our data indicated a possibility for measurement bias caused by the blending of health and function concepts in the SF-36.