Cross-cultural validation of the German version of the Four-Dimensional Symptom Questionnaire (4DSQ) in multimorbid elderly people

Purpose

Psychosomatic symptoms and mental health problems are highly prevalent in multimorbid elderly people challenging general practitioners to differentiate between normal stress and psychopathological conditions. The 4DSQ is a Dutch questionnaire developed to detect anxiety, depression, somatization, and distress in primary care. This study aims to analyze measurement equivalence between a German version and the original Dutch instrument.

Methods

A Dutch and a German sample of multimorbid elderly people, matched by gender and age, were analyzed. Equivalence of scale structures was assessed by confirmatory factor analysis (CFA). To evaluate measurement equivalence across languages, differential item functioning (DIF) was analyzed using Mantel–Haenszel method and hybrid ordinal logistic regression analysis. Differential test functioning (DTF) was assessed using Rasch analysis.

Results

A total of 185 German and 185 Dutch participants completed the questionnaire. The CFA confirmed one-factor models for all scales of both 4DSQ versions. Nine items in three scales were flagged with DIF. The anxiety scale showed to be free of DIF. DTF analysis revealed negligible scale impact of DIF.

Conclusions

The German 4DSQ demonstrated measurement equivalence to the original Dutch instrument. Hence, it can be considered a valid questionnaire for the screening for mental health problems in primary care.

     

Comparison of a qualitative and a quantitative approach to developing a household food insecurity scale for Bangladesh

This paper compares a qualitative and a quantitative (Rasch) method of item assessment for developing the content of a food insecurity scale for Bangladesh. Data are derived from the Bangladesh Food Insecurity Measurement and Validation Study, in which researchers collected 2 rounds of ethnographic information and 3 rounds of conventional household survey data between 2001 and 2003. The qualitative method of scale development relied on content experts and respondents themselves to evaluate household food insecurity items generated through ethnographic research. The quantitative method applied the Rasch model to assess the fit of the same items using representative survey data. The Rasch model was then used to test for differential item functioning (DIF) across diverse demographic and geographic subgroups. The qualitative assessment flagged and discarded 10 items, leaving 13. The Rasch assessment of infit and outfit flagged 3 items, and the Rasch DIF test discarded another 10 items, leaving a total of 10 items in the Rasch-derived scale. The 2 scales contained 8 of the same items. The qualitatively and quantitatively derived scales were highly correlated (r = 0.96, P < 0.01), and the 2 methods located 90% of households in the same food insecurity tercile. This convergence lends added confidence to the use of either scale for identifying food-insecure households in different regions of Bangladesh. Multiple methods should continue to be applied in a systematic and transparent way to lend additional credence to the results when they converge and to pinpoint directions for further clarification where they do not.     

Psychometric properties of the Mastery Scale-Chinese version: Applying classical test theory and Rasch analysis

Abstract

Aims: This study examines the reliability and validity of the Mastery Scale-Chinese version (MS-C) when applied to three groups diagnosed with major depression, schizophrenia, or HIV/AIDS. Methods: The individuals participating in the study were recruited from outpatient units of a medical center and a municipal hospital in northern Taiwan. The study sample (n = 2009) included 237 patients with depressive disorders, 160 with schizophrenia, and 1612 with HIV/AIDS. The reliability and construct validity of the MS-C was evaluated by confirmatory factor analysis (CFA) and Rasch analysis. Results: The results of the CFA showed that the MS-C has adequate construct validity with all indices meeting the criteria, except for chi-square values. The Rasch analysis supported the four-point rating scale structure and a unidimensional construct of the MS-C. The DIF analysis showed that all items demonstrated stable measurement properties among the different diagnosis groups (major depression, schizophrenia, HIV/AIDS). Conclusion: This study found that MS-C has acceptable psychometric qualities in terms of reliability, construct validity, rating scale performance, and item characteristics when applied to patients with depression, schizophrenia, and HIV/AIDS in Taiwan.     

Measuring social health in the patient-reported outcomes measurement information system (PROMIS): item bank development and testing

Purpose

To develop a social health measurement framework, to test items in diverse populations and to develop item response theory (IRT) item banks.

Methods

A literature review guided framework development of Social Function and Social Relationships sub-domains. Items were revised based on patient feedback, and Social Function items were field-tested. Analyses included exploratory factor analysis (EFA), confirmatory factor analysis (CFA), two-parameter IRT modeling and evaluation of differential item functioning (DIF).

Results

The analytic sample included 956 general population respondents who answered 56 Ability to Participate and 56 Satisfaction with Participation items. EFA and CFA identified three Ability to Participate sub-domains. However, because of positive and negative wording, and content redundancy, many items did not fit the IRT model, so item banks do not yet exist. EFA, CFA and IRT identified two preliminary Satisfaction item banks. One item exhibited trivial age DIF.

Conclusion

After extensive item preparation and review, EFA-, CFA- and IRT-guided item banks help provide increased measurement precision and flexibility. Two Satisfaction short forms are available for use in research and clinical practice. This initial validation study resulted in revised item pools that are currently undergoing testing in new clinical samples and populations.     

A Rasch and factor analysis of a Paramedic Graduate Attribute scale

This study examined the construct validity of the Paramedic Graduate Attribute scale (PGAS) using factor analysis and Rasch Analysis. A convenience sample was used in the study involving paramedics from all states and territories in Australia. Participants were asked to rate the importance of 47 graduate attribute items. Principal components analysis (PCA) was undertaken on the 47 items followed by Oblique Oblimin rotation. For the Rasch analysis item fit, item invariance and dimensionality were examined. A total of 872 paramedics participated in the study (23% response rate). PCA of the 47 items revealed seven factors with eigenvalues greater than 1, accounting for 40.6% of the total variance. The subsequent Rasch analyses based on the seven factors produced seven misfitting items and confirmed a 7-factor solution. The 7-factor PGAS produced a good fit to the Rasch Model and exhibited good reliability and unidimensionality, offering the Australian paramedic discipline a set of empirically based graduate attributes.     

Validation of the WHOQOL-BREF quality of life questionnaire for general use in New Zealand: confirmatory factor analysis and Rasch analysis

Purpose

The present study validated the abbreviated version of the World Health Organization Quality of Life (WHOQOL-BREF) questionnaire for general use in New Zealand.

Methods

A random postal sample from the national electoral roll was used, and 808 questionnaires were returned. Psychometric properties of the instrument were assessed, including tests of the four-domain factor structure using confirmatory factor analysis and Rasch analysis.

Results

Goodness-of-fit from the confirmatory factor analysis were good, and the overall conclusion of the Rasch analysis supported the confirmatory factor analysis (CFA) findings after dealing with problems of threshold ordering, local dependency, and differential item functioning (DIF).

Conclusions

The WHOQOL-BREF is valid for general use in New Zealand. In the future work, the WHOQOL-BREF domain scores should either be analyzed using non-parametric statistics or data should be fitted to the Rasch model to derive interval person estimates.     

Rasch analysis of an instrument for measuring occupational value: Implications for theory and practice

This study investigated psychometric properties of an instrument for assessing perceived occupational value, the 26-item OVal-pd. Data from 225 Swedish subjects with and without known mental illness were analysed regarding fit to the Rasch measurement model (partial credit model), differential item functioning (DIF), and functioning of the OVal-pd four-category response scale. The reliability (index of person separation, analogous to Cronbach's alpha) was good (0.92) but there were signs of overall and item level (six items) misfit. There was DIF between people with and without mental illness for three items. Iterative deletion of misfitting items resulted in a new 18-item DIF-free scale with good overall and individual item fit and maintained reliability (0.91). There were no disordered response category thresholds. These observations also held true in separate analyses among people with and without mental illness. Thus, the first steps of ensuring that occupational value can be measured in a valid and reliable way have been taken. Still, occupational value is a dynamic construct and the aspects that fit the construct may vary between contexts. This has implications for, e.g., cross-cultural research and calls for identification of a core set of culture-free items to allow for valid cross-cultural comparisons.     

Testing the structural and cross-cultural validity of the KIDSCREEN-27 quality of life questionnaire

Objectives

The aim of this study is to assess the structural and cross-cultural validity of the KIDSCREEN-27 questionnaire.

Methods

The 27-item version of the KIDSCREEN instrument was derived from a longer 52-item version and was administered to young people aged 8–18 years in 13 European countries in a cross-sectional survey. Structural and cross-cultural validity were tested using multitrait multi-item analysis, exploratory and confirmatory factor analysis, and Rasch analyses. Zumbo’s logistic regression method was applied to assess differential item functioning (DIF) across countries. Reliability was assessed using Cronbach’s alpha.

Results

Responses were obtained from n = 22,827 respondents (response rate 68.9%). For the combined sample from all countries, exploratory factor analysis with procrustean rotations revealed a five-factor structure which explained 56.9% of the variance. Confirmatory factor analysis indicated an acceptable model fit (RMSEA = 0.068, CFI = 0.960). The unidimensionality of all dimensions was confirmed (INFIT: 0.81–1.15). Differential item functioning (DIF) results across the 13 countries showed that 5 items presented uniform DIF whereas 10 displayed non-uniform DIF. Reliability was acceptable (Cronbach’s α = 0.78–0.84 for individual dimensions).

Conclusions

There was substantial evidence for the cross-cultural equivalence of the KIDSCREEN-27 across the countries studied and the factor structure was highly replicable in individual countries. Further research is needed to correct scores based on DIF results. The KIDSCREEN-27 is a new short and promising tool for use in clinical and epidemiological studies.     

Psychometric evaluation of the WHOQOL-BREF in community-dwelling older people in Taiwan using Rasch analysis

Objective  To examine the psychometric characteristics of the brief version of the World Health Organization Quality of Life (WHOQOL-BREF) questionnaire in rural-community-dwelling older people in Taiwan using Rasch analysis. Methods  This is a cross-sectional study. A total of 1200 subjects aged ≥65 years were recruited to complete the 26-item WHOQOL-BREF. Scale dimensionality, item difficulty, scale reliability and separation, item targeting, item-person map, and differential item functioning (DIF) were examined. Results  The four WHOQOL-BREF scales (physical capacity, psychological well-being, social relationships, and environment) were found to be unidimensional and reliable. The item–person map for each domain indicated that the spread of the item thresholds sufficiently covered the latent trait continuum being measured. However, gaps in content coverage were identified in the social domain. Analyses of the DIF revealed that one psychological item (body image) exhibited DIF across the two age groups (old–old vs. young–old) and that two social items (sexual activity and friends’ support) displayed DIF across genders and the two age groups. Conclusions  Rasch analysis is a comprehensive method of psychometric evaluation of the WHOQOL-BREF and identifies areas for improvements. Three items displaying age-related DIF (body image, sexual activity, and friends’ support) may potentially cause biased health-related QOL assessments, and their impacts on scores should be carefully examined.     

The study of the validity and reliability of the Occupational Self-Assessment-traditional Chinese version

IntroductionHealth professionals who work in mental healthcare settings need to use standardised, objective instruments; however, it is also extremely important that they maintain a client-focused perspective. The purpose of this study was to investigate the validity and reliability of the ‘Traditional Chinese version of the Occupational Self-Assessment’ (TC-OSA).MethodsA total of 593 participants with mental illnesses participated in the study. The data were analysed using confirmatory factor analysis as well as the Rasch measurement model.ResultsThe results of our analysis revealed that the TC-OSA encompasses four domains: self-performance (11 items), self-habituation (5 items), self-volition (5 items) and environment (8 items). Most of the items within each domain were found to have a good fit with the Rasch measurement model, whereas the CFA index was found to have a good fit for only three of the domains, the one exception being the environment domain.ConclusionsWe suggest applying the scale in clinical practice to identify the priority of intervention and as a measure for changes in outcomes. Further development and refinement of the environmental domain is guaranteed.     

The calibrated,unidimensional anxiety item bank for cardiovascular patients provided the basis for anxiety assessment in cardiovascular rehabilitation patients

ObjectiveComputer adaptive tests (CATs) offer a flexible, test fair, and economic opportunity for accurate measurement of anxiety in patients with cardiovascular diseases (CVDs). The objective of this study was to develop and calibrate an item bank [anxiety item bank for cardiovascular patients (AIB-cardio)] as a prerequisite for an anxiety-CAT in CVD patients.Study Design and SettingAfter pretesting for relevance and comprehension, a pool of 155 anxiety items was answered on a five-point Likert scale. Sample consisted of 715 CVD patients, who were recruited in 14 German cardiac rehabilitation centers. A confirmatory factor analysis (CFA), Mokken analysis, and Rasch analysis were conducted.ResultsThe results of CFA and Mokken analysis confirmed one factor structure and double monotonicity. In Rasch analysis, merging response categories and removing items with misfit, differential item functioning or local response dependency reduced the AIB-cardio to 37 items. The AIB-cardio fitted to the Rasch model with a nonsignificant item–trait interaction (chi-square, 133.89; degrees of freedom, 111; P = 0.07). Person separation reliability was 0.85, and unidimensionality could be verified.ConclusionThe calibrated, unidimensional AIB-cardio provides the basis for a CAT to assess anxiety in rehabilitation patients with CVD with good psychometric properties. Further testing in other cardiovascular patients is needed to increase generalizability.     

A Comparison of Depressive Symptoms in Stroke and Primary Care: Applying Rasch Models to Evaluate the Center for Epidemiologic Studies-Depression Scale

OBJECTIVES: Clinical trials and community-based studies often include the Center for Epidemiologic Studies-Depression scale (CES-D) as a measure of depression outcome. We compared responses to symptom-related items on the CES-D by depressed stroke and primary-care patients for several purposes: 1) to illustrate the use of Item Response Theory (IRT)-based (Rasch) models for comparing scale functioning across different patient subgroups; and 2) to inform clinicians and outcome researchers about scale functioning and depressive symptomatology in stroke- compared with primary care-based depression. METHODS: Two data sources were analyzed, including 32 depressed patients who were 3 months poststroke, and 366 depressed primary-care patients. Presence of depression was based on a CES-D score 16 or higher. Rasch models were used to assess item fit and compare item hierarchies between depressed primary-care and stroke patients. RESULTS: Item hierarchies were similar for poststroke depression and primary care-based depression. Interpersonal disruption items were the most difficult to endorse for both groups. No items misfit the scale in primary-care depression. Items relating to restless sleep, unfriendliness, and crying slightly misfit the scale in stroke patients, that is, may measure a different trait. Differential item functioning (DIF) between the groups was identified for items relating to appetite, restless sleep, crying, and feeling disliked. CONCLUSIONS: Results generally supported the use of the CES-D as measure of depression outcome, particularly in primary care-based depression. DIF may imply that slightly different clusters of depressive symptoms are reported by depressed stroke patients compared with primary care, but this is conjectural given the small stroke sample size and the same items have been previously associated with bias in studies of large nonstroke samples. This study found Rasch models to be useful tools to investigate scale performance for different clinical applications.     

Having a fit: impact of number of items and distribution of data on traditional criteria for assessing IRT’s unidimensionality assumption

Purpose  Confirmatory factor analysis fit criteria typically are used to evaluate the unidimensionality of item banks. This study explored the degree to which the values of these statistics are affected by two characteristics of item banks developed to measure health outcomes: large numbers of items and nonnormal data. Methods  Analyses were conducted on simulated and observed data. Observed data were responses to the Patient-Reported Outcome Measurement Information System (PROMIS) Pain Impact Item Bank. Simulated data fit the graded response model and conformed to a normal distribution or mirrored the distribution of the observed data. Confirmatory factor analyses (CFA), parallel analysis, and bifactor analysis were conducted. Results  CFA fit values were found to be sensitive to data distribution and number of items. In some instances impact of distribution and item number was quite large. Conclusions  We concluded that using traditional cutoffs and standards for CFA fit statistics is not recommended for establishing unidimensionality of item banks. An investigative approach is favored over reliance on published criteria. We found bifactor analysis to be appealing in this regard because it allows evaluation of the relative impact of secondary dimensions. In addition to these methodological conclusions, we judged the items of the PROMIS Pain Impact bank to be sufficiently unidimensional for item response theory (IRT) modeling.     

Rasch analysis of the Western Ontario McMaster (WOMAC) Osteoarthritis Index: results from community and arthroplasty samples

BACKGROUND AND OBJECTIVE: This study is based on secondary analysis of Western Ontario McMaster Osteoarthritis Index (WOMAC) data from a community sample over 55 years and total hip or knee arthroplasty samples presurgery and 1-year postoperative. METHODS: The WOMAC data were evaluated by Rasch analysis. Data were considered to fit the Rasch mathematical model for the pain and physical dimensions of the WOMAC if unidimensionality was confirmed by principle component analysis of the subscale and the residuals from the Rasch analysis, infit and outfit statistics were in the range of 0.80 to 1.20; if there was no differential item functioning based on gender or hip vs. knee subjects; and, if there was stability of the item logits across the three data samples. RESULTS: A three-item pain dimension (excluding night pain and pain on standing) and a 14-item physical dimension (excluding heavy domestic duties, getting in and out of the bath and getting on and off the toilet) fit the Rasch model based on these criteria. CONCLUSION: In evaluating existing health status questionnaires using Rasch methodology, it is important to evaluate relevant patient samples and longitudinal data when the measure is intended to evaluate change in status. By these criteria, a modified WOMAC questionnaire fits the Rasch model and has interval-level scaling properties.     

Construct Validity of the Swedish Version of the Revised Piper Fatigue Scale in an Oncology Sample—A Rasch Analysis

ObjectivesFatigue is a common and distressing symptom in cancer patients due to both the disease and its treatments. The concept of fatigue is multidimensional and includes both physical and mental components. The 22-item Revised Piper Fatigue Scale (RPFS) is a multidimensional instrument developed to assess cancer-related fatigue. This study reports on the construct validity of the Swedish version of the RPFS from the perspective of Rasch measurement.MethodsThe Swedish version of the RPFS was answered by 196 cancer patients fatigued after 4 to 5 weeks of curative radiation therapy. Data from the scale were fitted to the Rasch measurement model. This involved testing a series of assumptions, including the stochastic ordering of items, local response dependency, and unidimensionality. A series of fit statistics were computed, differential item functioning (DIF) was tested, and local response dependency was accommodated through testlets.ResultsThe Behavioral, Affective and Sensory domains all satisfied the Rasch model expectations. No DIF was observed, and all domains were found to be unidimensional. The Mood/Cognitive scale failed to fit the model, and substantial multidimensionality was found. Splitting the scale between Mood and Cognitive items resolved fit to the Rasch model, and new domains were unidimensional without DIF.ConclusionsThe current Rasch analyses add to the evidence of measurement properties of the scale and show that the RPFS has good psychometric properties and works well to measure fatigue. The original four-factor structure, however, was not supported.     

Evaluation of the Social Participation Questionnaire in adult patients with depressive symptoms using Rasch analysis

Purpose

The aim of this study was to explore the psychometric properties of the 22-item Social Participation Questionnaire (SPQ).

Methods

The SPQ was administered to 789 adult primary care patients with depressive symptoms. As the items were intended to be summed together to provide total score, Rasch analysis (partial credit model) was applied to assess the overall fit of the model, individual item fit, differential item functioning (DIF), targeting of persons, response dependency, unidimensionality and person separation.

Results

To improve the scale’s fit, it was necessary to re-score the response format. Two items demonstrated some DIF for gender and eight items showed DIF for age. To support the assumption of unidimensionality post hoc principal component analysis was performed. The analysis showed two subtests of the residuals with positive and negative loadings, but the person estimates derived from these two subtests were not statistically different to that derived from all items taken together. The response dependence between two items was identified; however, the magnitude of difficulty was very small. Although the questionnaire appeared to have insufficient items to assess the full spectrum of informal social contact, the SPQ was reasonably well targeted.

Conclusion

The SPQ is a promising questionnaire for the measurement of social participation although it could benefit from the inclusion of further items to measure informal social contact. This study found support for the internal validity, internal consistency reliability, and unidimensionality. A future study will investigate whether targeting can be improved when additional items are included.     

Rasch Measurement Properties of the KIDSCREEN Quality of Life Instrument in Children with Cerebral Palsy and Differential Item Functioning between Children with and without Cerebral Palsy

Objective:  To assess if the Rasch-scaled KIDSCREEN-52 generic health-related quality of life measure was valid in children with cerebral palsy (CP).
Methods:  The Rasch measurement properties and differential item functioning (DIF) of the KIDSCREEN-52 were examined in children with CP. Data were available from the KIDSCREEN project from 3219 children aged 8 to 12 years and 2126 parents in the general population; and from the SPARCLE project from 501 children aged 8 to 12 years with CP and 823 parents. Analysis used Zumbo's logistic regression DIF approach. Partial credit model analyses were conducted.
Results:  All items of the KIDSCREEN self-report version fitted the partial credit model (smallest P -value: 0.256). Only one item of the parent version did not fit the data well (smallest P -value 0.001). Statistically significant DIF was observed in some items, but was of substantial magnitude (Δ R ² = 0.046, 0.049) for only two items in two dimensions of the parent version. The practical impact of DIF was small. DIF-adjusted standardized mean differences between children with and without CP being 1.07 and 0.34 for the physical and school dimensions, respectively (unadjusted: 1.09 and 0.16).
Conclusion:  The KIDSCREEN-52 functions in a similar way in children with CP and in the general population. Comparisons of quality of life between such children are therefore likely to be valid.     

Simulated computerized adaptive tests for measuring functional status were efficient with good discriminant validity in patients with hip, knee, or foot/ankle impairments

BACKGROUND AND OBJECTIVE: To develop computerized adaptive tests (CATs) designed to assess lower extremity functional status (FS) in people with lower extremity impairments using items from the Lower Extremity Functional Scale and compare discriminant validity of FS measures generated using all items analyzed with a rating scale Item Response Theory model (theta(IRT)) and measures generated using the simulated CATs (theta(CAT)). METHODS: Secondary analysis of retrospective intake rehabilitation data. RESULTS: Unidimensionality of items was strong, and local independence of items was adequate. Differential item functioning (DIF) affected item calibration related to body part, that is, hip, knee, or foot/ankle, but DIF did not affect item calibration for symptom acuity, gender, age, or surgical history. Therefore, patients were separated into three body part specific groups. The rating scale model fit all three data sets well. Three body part specific CATs were developed: each was 70% more efficient than using all LEFS items to estimate FS measures. theta(IRT) and theta(CAT) measures discriminated patients by symptom acuity, age, and surgical history in similar ways. theta(CAT) measures were as precise as theta(IRT) measures. CONCLUSION: Body part-specific simulated CATs were efficient and produced precise measures of FS with good discriminant validity.     

A comparison of Rasch item‐fit and Cronbach's alpha item reduction analysis for the development of a Quality of Life scale for children and adolescents

Objective This study compares item reduction analysis based on classical test theory (maximizing Cronbach's alpha – approach A), with analysis based on the Rasch Partial Credit Model item‐fit (approach B), as applied to children and adolescents' health‐related quality of life (HRQoL) items. The reliability and structural, cross‐cultural and known‐group validity of the measures were examined. Methods Within the European KIDSCREEN project, 3019 children and adolescents (8–18 years) from seven European countries answered 19 HRQoL items of the Physical Well‐being dimension of a preliminary KIDSCREEN instrument. The Cronbach's alpha and corrected item total correlation (approach A) were compared with infit mean squares and the Q‐index item‐fit derived according to a partial credit model (approach B). Cross‐cultural differential item functioning (DIF ordinal logistic regression approach), structural validity (confirmatory factor analysis and residual correlation) and relative validity (RV) for socio‐demographic and health‐related factors were calculated for approaches (A) and (B). Results Approach (A) led to the retention of 13 items, compared with 11 items with approach (B). The item overlap was 69% for (A) and 78% for (B). The correlation coefficient of the summated ratings was 0.93. The Cronbach's alpha was similar for both versions [0.86 (A); 0.85 (B)]. Both approaches selected some items that are not strictly unidimensional and items displaying DIF. RV ratios favoured (A) with regard to socio‐demographic aspects. Approach (B) was superior in RV with regard to health‐related aspects. Conclusion Both types of item reduction analysis should be accompanied by additional analyses. Neither of the two approaches was universally superior with regard to cultural, structural and known‐group validity. However, the results support the usability of the Rasch method for developing new HRQoL measures for children and adolescents.     

Rasch Analysis of the General Self-Efficacy Scale in Workers with Traumatic Limb Injuries

Purpose The purpose of this study was to apply Rasch analysis to examine the unidimensionality and reliability of the General Self-Efficacy Scale (GSE) in workers with traumatic limb injuries. Furthermore, if the items of the GSE fitted the Rasch model’s assumptions, we transformed the raw sum ordinal scores of the GSE into Rasch interval scores. Methods A total of 1076 participants completed the GSE at 1 month post injury. Rasch analysis was used to examine the unidimensionality and person reliability of the GSE. The unidimensionality of the GSE was verified by determining whether the items fit the Rasch model’s assumptions: (1) item fit indices: infit and outfit mean square (MNSQ) ranged from 0.6 to 1.4; and (2) the eigenvalue of the first factor extracted from principal component analysis (PCA) for residuals was <2. Person reliability was calculated. Results The unidimensionality of the 10-item GSE was supported in terms of good item fit statistics (infit and outfit MNSQ ranging from 0.92 to 1.32) and acceptable eigenvalues (1.6) of the first factor of the PCA, with person reliability = 0.89. Consequently, the raw sum scores of the GSE were transformed into Rasch scores. Conclusions The results indicated that the items of GSE are unidimensional and have acceptable person reliability in workers with traumatic limb injuries. Additionally, the raw sum scores of the GSE can be transformed into Rasch interval scores for prospective users to quantify workers’ levels of self-efficacy and to conduct further statistical analyses.