Differential Item Research Articles

Applicability and clinical utility of the German rivermead post-concussion symptoms questionnaire in proxies of children after traumatic brain injury: an instrument validation study.

The German Rivermead Post-Concussion Symptoms Questionnaire (RPQ) can be used to assess post-concussion symptoms (PCS) after traumatic brain injury (TBI) in adults, adolescents, and children. In this study, we examined the psychometric properties of the German RPQ proxy version (N = 146) for children (8-12 years) after TBI at the item, total and scale score level. Construct validity was analyzed using rank correlations with the proxy-assessed Post-Concussion Symptoms Inventory (PCSI-P), the Patient Health Questionnaire 9 (PHQ-9), and the Generalized Anxiety Disorder Scale 7 (GAD-7). Furthermore, sensitivity testing was performed concerning subjects' sociodemographic and injury-related characteristics. Differential item functioning (DIF) was analyzed to assess the comparability of RPQ proxy ratings for children with those for adolescents. Good internal consistency was demonstrated regarding Cronbach's α (0.81-0.90) and McDonald's ω (0.84-0.92). The factorial validity of a three-factor model was superior to the original one-factor model. Proxy ratings of the RPQ total and scale scores were strongly correlated with the PCSI-P (ϱ = 0.50-0.69), as well as moderately to strongly correlated with the PHQ-9 (ϱ = 0.49-0.65) and the GAD-7 (ϱ = 0.44-0.64). The DIF analysis revealed no relevant differences between the child and adolescent proxy versions. The German RPQ proxy is a psychometrically reliable and valid instrument for assessing PCS in children after TBI. Therefore, RPQ self- and proxy-ratings can be used to assess PCS in childhood as well as along the lifespan of an individual after TBI.

A Psychometric Evaluation of the Dysphagia Handicap Index Using Rasch Analysis.

Background/Objectives: The Dysphagia Handicap Index (DHI) is commonly used in oropharyngeal dysphagia (OD) research as a self-report measure of functional health status and health-related quality of life. The DHI was developed and validated using classic test theory. The aim of this study was to use item response theory (Rasch analysis) to evaluate the psychometric properties of the DHI. Methods: Prospective, consecutive patient data were collected at dysphagia or otorhinolaryngology clinics. The sample included 256 adults (53.1% male; mean age 65.2) at risk of OD. The measure's response scale, person and item fit characteristics, differential item functioning, and dimensionality were evaluated. Results: The rating scale was ordered but showed a potential gap in the rating category labels for the overall measure. The overall person (0.91) and item (0.97) reliability was excellent. The overall measure reliably separated persons into at least three distinct groups (person separation index = 3.23) based on swallowing abilities, but the subscales showed inadequate separation. All infit mean squares were in the acceptable range except for the underfitting for item 22 (F). More misfitting was evident in the Z-Standard statistics. Differential item functioning results indicated good performance at an item level for the overall measure; however, contrary to expectation, an OD diagnosis presented only with marginal DIF. The dimensionality of the DHI showed two dimensions in contrast to the three dimensions suggested by the original authors. Conclusions: The DHI failed to reproduce the original three subscales. Caution is needed using the DHI subscales; only the DHI total score should be used. A redevelopment of the DHI is needed; however, given the complexities involved in addressing these issues, the development of a new measure that ensures good content validity may be preferred.

Piloting Rasch model scoring of the National Eye Institute Visual Function Questionnaire in uveitis

IntroductionThe National Eye Institute Visual Function Questionnaire (NEI VFQ) is a common patient-reported outcome measure (PROM) in uveitis trials. Its psychometric properties using state-of-the-art scoring based on Rasch models, a latent trait model that improves accuracy of PROMs assessment, has not yet been investigated.MethodsThe study participants were recruited online from uveitis patient organizations, where individuals self-reported their uveitis diagnosis and visual acuity level. These participants then completed the NEI VFQ-25. The visual function (VF) and socioemotional (SE) subscales were psychometrically analysed in terms of item fit, targeting, internal consistency, dimensionality, and differential item functioning (DIF), using Rasch models. Criterion validity was examined based on associations between NEI VFQ person measures and recent visual acuity (VA) levels.ResultsNinety-nine participants recruited online from uveitis patient organizations (68 women, 31 men; mean age 50 ± 15 years; 46.5% self-reported receiving systematic therapy for uveitis, 0.6% NEI VFQ-25 missing data) were included. The mean difficulty of items was lower than the average person ability. None of the items demonstrated misfit to an extent that would induce noise into the measurement. The consistency metrics person reliability and person separation index of the subscales were 0.85 and 2.34 (NEI VFQ-VF), 0.86 and 2.52 (NEI VFQ-SE), respectively. There was no evidence of multidimensionality and none of the items showed DIF by gender. The differences between item and person measures were 1.44 (NEI VFQ-VF) and 1.03 (NEI VFQ-SE). NEI VFQ-25 person measures were significantly lower in participants with visual impairment (all p values ≤ 0.007).ConclusionRasch model-based scoring of the re-engineered NEI VFQ-25 demonstrates acceptable internal consistency, item fit and construct validity for assessing two key domains of quality of life in individuals self-reporting uveitis. The PROM was targeted at a higher level of difficulty than present in our heterogeneous sample.

Baby Observational Selective Control AppRaisal (BabyOSCAR): Construct validity and test performance.

To investigate the construct validity of the Baby Observational Selective Control AppRaisal (BabyOSCAR), an assessment of independent joint motion in infants with cerebral palsy (CP). BabyOSCAR was scored for 75 infants (45 with CP and 30 without CP). Rasch analysis was used in combination with classical test theory to assess areas of strength or improvement. Overall fit and precision, unidimensionality, local independence, reliability indices, Wright's child-item map, and differential item functioning were examined as part of Rasch analysis to investigate the item properties, internal construct validity, and reliability of BabyOSCAR. Cronbach's α was used to evaluate items' internal consistency. Analysis demonstrated good fit to the Rasch model, with only one erratic item. Unidimensionality results suggest two dimensions, split between arm and leg items. Item calibration reliability was between 0.84 and 0.86, with three distinct item difficulty levels. Infant measure reliability was between 0.82 and 0.91, separating infants into three ability levels. Together, the two subscales covered the full range of skills, with redundancy mostly between the same motion on both sides of the body. Cronbach's α was between 0.90 and 0.95. BabyOSCAR's construct validity was supported. Arm and leg subscales can be translated to a logit scale. Baby Observational Selective Control AppRaisal (BabyOSCAR) has excellent construct validity with good overall fit and precision. Individual BabyOSCAR items contribute and work well together, forming an interval-level assessment. BabyOSCAR has two separate subscales, arms and legs, that complement each other. BabyOSCAR's items represent a continuum of skills with three distinct difficulty levels. BabyOSCAR's continuum of skills reliably separates infants into three ability levels.

Assessment of adult cognitive abilities in Greece: A differential item functioning study of the General Ability Measure for Adults (GAMA)

The purpose of this study was to evaluate the generalizability and possible adaptation for use of a non-verbal measure of intelligence developed in the United States, the General Ability Measure for Adults (GAMA; Naglieri & Bardos, 1997) in Greece. As a validity evidence the study examined the differential item function of its questions in order to explore potential item bias utilizing the disproportionate group probabilities of participants’ correctly endorsing test items. The analysis was performed using a logistic regression procedure with samples from the United States (n = 2,369) and Greece (n = 1,273). The findings indicate a small (<1%) number of items that work differentially between these two cultural groups. Implications for the development and weighting of cross-cultural intelligence assessment tests using non-verbal measures are discussed.

Cross-cultural adaptation, validity and reliability of the Japanese version of ABILHAND-kids for children with cerebral palsy using Rasch measurement model

Purpose The aim of this study was to develop the Japanese version of the ABILHAND-Kids and to examine its psychometric properties for Japanese children with cerebral palsy (CP). Methods The experimental version of 75 items was developed using forward-backward translation method. Parents of 137 children with CP answered it. Their responses were analyzed to successive items, and psychometric properties of the final version were investigated through the Rasch measurement model. Results The Japanese version of the ABILHAND-Kids contained 22 items. It showed valid item-patient targeting, no significant floor and ceiling effects, and no differential item functioning for demographic and clinical subgroups. All items contributed to the definition of one-dimensional measure. For internal consistency, the person separation index was 0.94. For test-retest reliability, the intraclass correlation coefficients were 0.96 (95% CI: 0.92–0.98). The minimal detectable difference was calculated with a logit score of 0.79 and a total raw score of 4.50. The logit score showed a strong correlation with the Manual Ability Classification System level (ρ= −0.70) and the Gross Motor Function Classification System level (ρ= −0.62). Conclusions The Japanese version of the ABILHAND-Kids was found to be valid and reliable. It appears to be a good tool for assessing manual abilities in daily activities in children with CP.

A Framework for Detecting Both Main Effect and Interactive DIF in Multidimensional Forced-Choice Assessments

In recent decades, multidimensional forced-choice (MFC) tests have gained widespread popularity in organizational settings due to their effectiveness in reducing response biases. Detecting differential item functioning (DIF) is crucial in developing MFC tests, as it relates to test fairness and validity. However, existing methods appear insufficient for detecting DIF induced by the interaction between multiple covariates. Furthermore, for multi-category, ordered or continuous covariates, existing approaches often dichotomize them using a-priori cutoffs, commonly using the median of the covariates. This may lead to information loss and reduced power in detecting MFC DIF. To address these limitations, we propose a method to identify both main effect DIF and interactive DIF. This method can automatically search for the optimal cutoffs for ordered or continuous covariates without pre-defined cutoffs. We introduce the rationale behind the proposed method and evaluate its performance through three Monte Carlo simulation studies. Results demonstrate that the proposed method effectively identifies various DIF forms in MFC tests, thereby increasing detection power. Finally, we provide an empirical application to illustrate the practical applicability of the proposed method.

Differential and Functional Response Time Item Analysis: An Application to Understanding Paper versus Digital Reading Processes

AbstractDespite the growing interest in incorporating response time data into item response models, there has been a lack of research investigating how the effect of speed on the probability of a correct response varies across different groups (e.g., experimental conditions) for various items (i.e., differential response time item analysis). Furthermore, previous research has shown a complex relationship between response time and accuracy, necessitating a functional analysis to understand the patterns that manifest from this relationship. In this study, response time data are incorporated into an item response model for two purposes: (a) to examine how individuals' speed within an experimental condition affects their response accuracy on an item, and (b) to detect the differences in individuals' speed between conditions in the presence of within‐condition effects. For these two purposes, by‐variable smooth functions are employed to model differential and functional response time effects by experimental condition for each item. This model is illustrated using an empirical data set to describe the effect of individuals' speed on their reading comprehension ability in two experimental conditions of reading medium (paper vs. digital) by item. A simulation study showed that the recovery of parameters and by‐variable smooth functions of response time was satisfactory, and that the type I error rate and power of the test for the by‐variable smooth function of response time were acceptable in conditions similar to the empirical data set. In addition, the proposed method correctly identified the range of response time where between‐condition differences in the effect of response time on the probability of a correct response were accurate.

Translation and validation of the Chinese self-report version of Spinal Cord Independence Measure (SCIM-SR): Rasch psychometric analysis and online application

Spinal Cord Independence Measure (SCIM) was an important functional outcome measure specifically designed for spinal cord injury (SCI) patients, with the self-reported version of SCIM (SCIM-SR) published in 2013. This study aims to translate the SCIM-SR into Chinese, and to investigate the validity of Chinese SCIM-SR among SCI patients. This Chinese version of SCIM-SR was translated into Chinese in a standardized approach, and then filled out by a sample of patients with SCI (n = 205) within 3 days after admission. Validity of Chinese SCIM-SR was then analyzed using Rasch analysis and principal component analysis. The subscale Selfcare and subscale Mobility showed good fit to the Rasch model, with no significance found in Chi-square test results for item-trait interaction, using Bonferroni adjustment for the significant level (χ2 =18.125, P = 0.111; χ2 =33.629, P = 0.006). Mean fit residual for items and persons of each subscale were within ± 2.5. The model fit of the subscale of Respiration and Sphincter Management was not satisfactory even after deleting one item and merging two items with local dependence. However, Kaiser-Meyer-Olkin test was > 0.50 in total score and all the subscales of Chinese SCIM-SR, and P < 0.05 in the Bartlett’s test. There was no differential item functioning for gender, time post injury, age, and etiology in any of the three subscales. An online version of Chinese SCIM-SR was also developed. It is concluded that the SCIM-SR in Chinese is valid for application in individuals with SCI. SCIM-SR is considered as an important tool for self-reporting functional status from SCI individuals’ perspective.

The Ethiopian Cognitive Assessment battery in Schizophrenia (ECAS): a validation study

Cognitive impairment is common in people with schizophrenia (PWS). To detect the presence and its consequences, cognitive measures with sound psychometric properties are needed. However, these are lacking especially in low-income countries. Hence, we developed the Ethiopian Cognitive Assessment battery in Schizophrenia (ECAS). In this study, we evaluated the psychometric properties of the ECAS in a cross-sectional study involving 350 PWS. Confirmatory factor analysis demonstrated a one-factor solution. ECAS score correlated significantly but weakly with a disability measure (r = −0.13, p = 0.02) and symptom dimensions of PANSS (r between −0.12 and −0.29, p < 0.05), except for positive symptoms (r = −0.10, p > 0.05). Years of education (β = 0.12, 95% CI (0.09, 0.14), p < 0.001), male sex (β = 0.22, 95% CI (0.05, 0.39)), age β = −0.02, 95% CI (−0.03, −0.01), and medication side effects (β = −0.03, 95% CI (−0.06, −0.01), p = 0.021) were significantly associated with the composite score of ECAS. The Item Response Theory analysis showed that the tool best functions among participants with moderate cognitive impairment (difficulty coefficient between −1.12 and 0.27). The Differential Item Functioning analyses showed that education had a positive contribution on Digit Symbol Substitution Test (MH OR = 2.64, 95% CI (1.34, 5.20)). The results showed that ECAS is valid in assessing cognition in PWS in low-resource settings.

Attitude Is Everything: Examining Acceptance of Violence Items for Differential Item Functioning Across Heterosexual and Sexual Minority Youth.

Acceptance of dating violence (ADV) is a cognitive risk factor for violence perpetration and a common target of prevention programs. However, frequently used items assessing ADV are characterized by heteronormative item wording, and limited research has evaluated the degree to which ADV items function equivalently for both heterosexual and sexual minority youth (SMY). The current study sought to determine if there are differences in the way heterosexual and SMY respond to ADV survey items. Secondary data from a total of 2,014 adolescents (Mage = 16.78) were used to examine differences in ADV. Results of differential item functioning analysis indicated nonuniform differential item functioning for two of eight ADV items, with heterosexual youth being more likely to express strong levels of agreements with (a) female-perpetrated physical violence in response to male-perpetrated violence and (b) female-perpetrated violence against males broadly, relative to SMY. Although these differences were of negligible magnitude and only resulted in minimal differences in overall expected average scores, heterosexual youth were more likely to strongly accept female-perpetrated dating violence compared to SMY. Findings highlight differences in ADV item response patterns across heterosexual and sexual minority identifying youth and provide preliminary evidence for group differences in acceptance of female-perpetrated dating violence. Implications for prevention programming based on current findings include greater focus on measure adaptation and development as well as more consensus on the necessity of preventing female-perpetrated violence.

Smooth Information Criterion for Regularized Estimation of Item Response Models

Item response theory (IRT) models are frequently used to analyze multivariate categorical data from questionnaires or cognitive test data. In order to reduce the model complexity in item response models, regularized estimation is now widely applied, adding a nondifferentiable penalty function like the LASSO or the SCAD penalty to the log-likelihood function in the optimization function. In most applications, regularized estimation repeatedly estimates the IRT model on a grid of regularization parameters λ. The final model is selected for the parameter that minimizes the Akaike or Bayesian information criterion (AIC or BIC). In recent work, it has been proposed to directly minimize a smooth approximation of the AIC or the BIC for regularized estimation. This approach circumvents the repeated estimation of the IRT model. To this end, the computation time is substantially reduced. The adequacy of the new approach is demonstrated by three simulation studies focusing on regularized estimation for IRT models with differential item functioning, multidimensional IRT models with cross-loadings, and the mixed Rasch/two-parameter logistic IRT model. It was found from the simulation studies that the computationally less demanding direct optimization based on the smooth variants of AIC and BIC had comparable or improved performance compared to the ordinarily employed repeated regularized estimation based on AIC or BIC.

Relating violations of measurement invariance to group differences in response times.

Measurement invariance is an assumption underlying the regression of a latent variable on a background variable. It requires the measurement model parameters of the latent variable to be equal across the levels of the background variable. Item-specific violations of this assumption are referred to as differential item functioning and are ideally substantively explainable to warrant theoretically valid and meaningful results. Past research has focused on developing statistical approaches to explain differential item functioning effects in terms of item- or person-specific covariates. In this study, we propose a modeling approach that can be used to test if differences in item response times can be used to statistically explain differential item functioning. To this end, we operationalize a latent response process factor and test if item-specific group differences on this factor can account for the observed differences in item scores. We investigate the properties of the model in a simulation study, and we apply the model to a real data set. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Evaluating the Validity and Measurement Invariance of the Patient Health Questionnaire-9 Among Canadian Nurses.

Background and Purpose: The patient health questionnaire 9 item (PHQ-9) is a widely used self-reported measure for screening depressive symptoms. This study aims to examine measurement invariance and psychometric properties of the PHQ-9 for screening depressive symptoms in nurses across different nursing roles, gender, and workplace sector. Methods: The study is a secondary analysis of pre-COVID and COVID-19 survey data from 4,176 nurses and 3,238 nurses in British Columbia. Data from the PHQ-9 tested the assumption of unidimensionality, reliability, and presence of differential item functioning (DIF). Results: The PHQ-9 showed excellent internal consistency (r = .9) and a unidimensional factor structure. PHQ-9 items were free of DIF across nursing roles, gender, and workplace sector. Conclusions: This study supported the valid use of the PHQ-9 as a screening tool for depressive symptoms among nurses.

Development and initial validation of the Multifaceted Instrument for Body Image Disturbance (MI-BoD).

Specific facets of body image disturbance have an important role in eating disorder (ED) onset and maintenance yet have been assessed with single items and/or questionnaires predominantly developed in female samples to capture desire for a thinner body. The aim of this multipart study was to develop the multifaceted instrument for body image disturbance (MI-BoD) that will assess body image disturbance across gender and body size. In Study 1, interviews were conducted with 31 ED lived experience experts (45% females) to develop an initial item pool which was then rated for relevance and clarity by 59 international field experts, shortened and refined by the research team, and then rerated by 20 field experts and 91 ED lived experience experts. Of the 477 items developed from interviews, 46 were retained for the initial validation study. In Study 2, the MI-BoD was administered to undergraduate students (N = 937; 84% females), community adolescents (N = 208; 58% females), and individuals with self-reported ED diagnosis (N = 410; 77% females) to assess its preliminary psychometric properties. Exploratory factor analysis revealed six underlying factors, namely, Dissatisfaction, Overvaluation, Preoccupation, Fear of Weight Gain, Body Checking, and Body Exposure. No differential item functioning was detected for most MI-BoD items across gender, weight status, and ED status (symptomatic vs. asymptomatic). Overall, the MI-BoD showed good internal consistency, convergent and divergent validity, concurrent validity, and test-retest reliability. In conclusion, the MI-BoD is a promising tool for assessment of important facets of body image disturbance across gender, body size, and ED symptomatology. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Construction and Normalization of Competency Evaluative Indicators based on the Screening of Psychological and Personality Fundamental Scales with the Third Edition of Minnesota Multiphasic Personality Inventory (MMPI-3)

This research aimed to construct, validate and normalize a measuring scale of competency evaluative indicators based on the screening of psychological and personality fundamental scales with the Third Edition of Minnesota Multiphasic Personality Inventory (MMPI-3). Present study aimed that competency indicators can be measured with a validate instrument named MMPI-3. We assessed the validity of this new measure applied to 3000 participating from Iran. We obtained evidence for (a) content validity (through item analysis), (b) internal structure with Mokken Scaling Analysis and structural equation modeling to examine the item–construct relationship, differential item functioning, and reliability, and (c) association with external variables. The items were found to function one-dimensionally, with strong item–construct relationships and no differential functioning. Theoretically consistent associations were found between scales of MMPI-3 and constructed Indicators by researchers. The findings of the present study shown that (a) we can assess competency indicators as second layer of MMPI-3 profile, (b) there’s a strong correlation among competency indicators and MMPI-3 scales as reverse layer and (c) constructed indicators by researchers are validate and reliable to assess competency indicators for evaluating and screening psychological and personality features

Differential Item Functioning Along the Old Age Continuum: Contrasting Chronological Age With Contextual Variables in the Assessment of Gains and Losses Across Advanced Old Age.

The fourth age is considered a life stage with a high likelihood of age-related losses. However, very old age extends over decades, and little is known about how transitions that may happen during this age period (e.g., developing support needs or adopting caregiving roles) or lack thereof might change perceptions of age-related gains or losses. Many subjective age scales assume implicitly that they work across advanced old age, but data to support this assumption are scarce. This study reports findings on (1) diverging, age-specific understandings of age-related change and (2) whether very old adults' functional health, received social support, and caregiving roles, rather than chronological age, account for such differences. Data came from the nationally representative survey "Old Age in Germany D80+" conducted in 2020/2021, comprising 10,578 individuals aged 80-106 years. At equivalent levels of perceived gains and losses, adults in the early fourth age reported more "freedom in daily life," less "dependency on others," and fewer "needs to reduce activities," whereas adults in the late fourth age reported more "appreciation of others." Chronological age, as such, was not the primary source of this response shift. Rather, functional health, social support, and caregiving responsibilities accounted for the differences in how older adults interpreted and reported specific age-related gains and losses. Findings underscore that across the multiple decades of the fourth age, interpretations of aging experiences vary and depend on a person's own late-life health and functioning and on that of significant others.

라이프스타일에 반영된 가치체계 평가도구(Yonsei Lifestyle Profile-Values)의 구성 타당성: 이중요인(Bifactor) 모델 접근

Objective: The construct validity and reliability of the Yonsei Lifestyle Profile-Values (YLP-V) were verified to measure the value system reflected in lifestyle behaviors. Methods: Data were collected from 300 community-dwelling older adults aged 55 years and older who were registered with an online research organization. The YLP-V was used to collect data, which underwent descriptive statistics, differential item functioning, and factor analysis. Exploratory factor analysis was conducted to estimate the factor structure, and confirmatory factor analysis was used to compare and confirm the validity of four competing models (single-factor, hierarchical factor, multidimensional factor, and bifactor). Results: Exploratory factor analysis using target rotation revealed that the dimensions of the YLP-V (activity, five items; interest, four items; opinion, nine items) showed factor loadings of 0.4 or higher, indicating good construct validity. Confirmatory factor analysis indicated that the bifactor model (χ2 = 164.58**, degree of freedom = 117, root mean square error of approximation = 0.05, standard root mean residual = 0.04, comparative fit index = 0.95, Turker Lewis index = 0.93) demonstrated the best fit among the tested models. Conclusion: We identified a factor structure consistent with evidence for developing the YLP-V, which allows for a micro-level lifestyle approach. The bifactor structure, with 18 items representing activity, interest, and opinion, demonstrated validity, and the YLP-V could be valuable for measuring and understanding the value systems reflected in behaviors within a healthy lifestyle.

Age-Neutral Measurement Of Personality Functioning and Maladaptive Personality Traits.

As previous studies have shown that personality disorder (PD) assessment in older adults is often hampered because assessment tools are tailored toward younger adults, establishing the age-neutrality of novel tools is crucial. This study primarily aimed to evaluate the age-neutrality of the Level of Personality Functioning Brief Form (LPFS-BF 2.0) and the Personality Inventory for DSM-5 Modified + (PID-5-BF+M), using a sample of 254 community-dwelling adults. The analysis of Differential Item Functioning (DIF) demonstrated the age-neutrality of both instruments, with only 8.3% of LPFS-BF 2.0 items and 5.6% of PID-5-BF+M items exhibiting DIF. Differential Test Functioning (DTF) analyses revealed large DTF for the LPFS-BF 2.0 total score, indicating that age-specific norms might be necessary for this score. In summary, this study supports the use of these instruments in both older and younger adults, enhancing the assessment of PDs across the life span.

Development of a rapid tool for screening financial toxicity based on the comprehensive score for financial toxicity

ObjectiveThis study aimed to use item response theory (IRT) to develop and validate a short version of the Chinese COmprehensive Score for financial Toxicity (COST-S-C) in patients with cancer. MethodsA total of 500 patients with cancer participated in the survey. Confirmatory factor analysis (CFA) was used to assess the factor structure of the COST-S-C. A two-parameter IRT model was used to examine the item fit of the COST-S-C. Item discrimination, item characteristic curves (ICCs), item information curves (IICs), and item fit were estimated. Differential item functioning (DIF) was assessed for participants’ gender and age. Reliability, convergent and discriminant validity was examined as well as estimating the optimal cut-off points of the COST-S-C. ResultsThe CFA results supported the bi-factor structure of the COST-S-C. The IRT analysis findings revealed that several items showed problems with the ICCs, providing little information in terms of IICs as well as poor discrimination. Item 5 showed a negligible DIF problem with age. A valid 3-item COST-S-C scale and its optimal cut-off point was developed. ConclusionsThe COST-S-C is a valid and quick screening tool used to distinguish patients with cancer who report significant financial toxicity in various medical settings.