Although Item Response Theory (IRT) has been recommended for helping advance interprofessional education (IPE) research, its use remains limited. This may be partly explained by potential misconceptions regarding IRT`s \"limitation\" to cross-sectional data. The aim of this study is to demonstrate how Item Response Theory (IRT) can be applied effectively in before-and-after designs in IPE research. Specifically, a two-week before-after design with survey methodology using the Extended Professional Identity Scale (EPIS), an interprofessional identity measure, was conducted among n = 146 mixed health-science students. Results indicated that EPIS increased significantly before-after intervention by .74 standardised mean differences, t146 = 7.73, p < .05. The before-after IRT model also gave a test-retest reliability estimate of .60 which was considered acceptable. Comparison of the IRT model with a conventional paired-t-test indicated similar effect size estimates of Cohen\'s d = .56 and .54, respectively. We demonstrate IRT`s flexibility to before-after studies in IPE. Application of this model can yield accurate changes in target IPE constructs, and it is advantageous to classical test theory vis-à-vis baseline differences.

OBJECTIVE: The Oxford Knee Score (OKS) and OKS Activity and Participation Questionnaire (OKS-APQ) are patient reported outcome measures used to assess people undergoing knee replacement surgery. They have not explicitly been tested for unidimensionality (whether they measure one underlying trait such as \'knee health\'). This study applied item response theory (IRT) to improve the validity of the instruments to optimise for ongoing use.
METHODS: Participants undergoing primary total knee replacement (TKR) provided pre-operative and post-operative responses for OKS and OKS-APQ. Confirmatory factor analyses (CFA) were performed on the OKS and OKS-APQ separately, and then on both when pooled into one. An IRT model was fitted to the data.
RESULTS: 2972 individual response patterns were analysed. CFA demonstrated that when combining OKS and OKS-APQ as one instrument, they measure one latent health trait. A user-friendly, free-to-use, web app has been developed to allow clinicians to upload raw data and instantly receive IRT scores.
CONCLUSIONS: The OKS and OKS-APQ can be combined to use effectively as a single instrument (producing a single score). For the separate OKS and OKS-APQ the original items and response options can continue to be posed to patients, and this study has confirmed the suitability of IRT-weighted scoring. Applying IRT to existing responses, converts traditional sum scores into continuous measurements with greater granularity including individual measurement error.

We examined the longitudinal psychometric properties of the Perceived Stress Scale - 4 items version (PSS-4) using item response theory with a sample of 361 mental health counsellors. Participants completed the PSS-4 at three timepoints at six-month intervals in a one-year period. There were 290 participants who (80.3%) identified as female, 51 (14.1%) identified as male, eight (2.2%) identified as gender variant/non-conforming, seven (1.9%) wrote in their own gender identity (e.g., genderqueer, gender expansive), three (0.8%) identified as Transgender male, and two (0.6%) did not respond to the item. The racial and ethnic backgrounds were as follows: White (87.3%), Multiracial (5.5%), Latino or Hispanic or Spanish (2.8%), Black or African American (1.4%), Asian (0.8%), Middle Eastern (0.8%), and five did not respond to the item (1.4%). We found unidimensionality evidence of the PSS-4 across all three timepoints and response categories were monotonically ordered. We also found that across all timepoints, the average person location was lower than the average item location, suggesting that the PSS-4 may not be well-targeted for this sample of mental health counsellors. We observed no significant interactions between timepoints, hours worked per week, and length of employment. Implications of the findings, including a discussion of the utility of the PSS-4 as a global measure of stress and with mental health counsellors.

BACKGROUND: Neurodevelopmental performance tasks are often separately analyzed, even when they tap into a similar construct. This may yield mixed findings for associations of an exposure-neurobehavioral outcome. We develop an item response theory (IRT) approach to integrate multiple task variables together to improve measurement precision of the underlying construct. We apply this approach to create an integrative measure of childhood inhibitory control, and study impacts of pre/post-natal lead exposure.
METHODS: Using data from a prospective cohort based in Mexico (N = 533), we created an inhibitory control scale that integrates accuracy and reaction time information from four inhibitory control tasks (Go/NoGo Letter, Go/NoGo Neutral, Go/NoGo Happy, Delis-Kaplan Executive Function System (D-KEFS) Color-Word Interference Test, Condition 3). Using a generalized partial credit item response theory model, we estimated an inhibitory control index for each participant. We then assessed adjusted associations between umbilical cord blood and 4-year lead and childhood inhibitory control. We developed a resampling approach to incorporate error estimates from the inhibitory control variable to confirm the consistency of the lead-inhibitory control associations. We modeled time-varying associations of lead with each inhibitory control measure separately.
RESULTS: Participants had a median age of 9 years; 51.4% were males. Umbilical cord blood [-0.06 (95% CI: -0.11, -0.01)] and 4-year lead [-0.07 (95% CI: -0.12, -0.02)] were associated with inhibitory control index at 8-10 years. A resampling approach confirmed that 4-year lead was consistently associated with childhood inhibitory control index. Umbilical cord blood and 4-year lead were each associated with 3 out of 8 measures in separate models.
CONCLUSIONS: This is the first application of IRT in environmental epidemiology to create a latent variable for inhibitory control that integrates accuracy and reaction time information from multiple, related tasks. This framework can be applied to other correlated neurobehavioral assessments or other phenotype data.

BACKGROUND: Computerized adaptive testing (CAT) is an effective way to reduce time, repetitious redundancy, and respond burden, and has been used to measure outcomes in many diseases. This study aimed to develop and validate a comprehensive disease-specific CAT for chronic obstructive pulmonary disease (COPD) patient-reported outcome measurement.
METHODS: The discrimination and difficulty of the items from the modified patient-reported outcome scale for COPD (mCOPD-PRO) were analyzed using item response theory. Then the initial item, item selection method, ability estimation method, and stopping criteria were further set based on Concerto platform to form the CAT. Finally, the reliability and validity were validated.
RESULTS: The item discrimination ranged from 1.05 to 2.71, and the item difficulty ranged from - 3.08 to 3.65. The measurement reliability of the CAT ranged from 0.910 to 0.922 using random method, while that ranged from 0.910 to 0.924 using maximum Fisher information (MFI) method. The content validity was good. The correlation coefficient between theta of the CAT and COPD assessment test and modified Medical Research Council dyspnea scale scores using random method was 0.628 and 0.540 (P < 0.001; P < 0.001) respectively, while that using MFI method was 0.347 and 0.328 (P = 0.007; P = 0.010) respectively. About 11 items (reducing by 59.3%) on average were tested using random method, while about seven items (reducing by 74.1%) on average using MFI method. The correlation coefficient between theta of the CAT and mCOPD-PRO total scores using random method was 0.919 (P < 0.001), while that using MFI method was 0.760 (P < 0.001).
CONCLUSIONS: The comprehensive disease-specific CAT for COPD patient-reported outcome measurement is well developed with good psychometric properties, which can provide an efficient, accurate, and user-friendly measurement for patient-reported outcome of COPD.

OBJECTIVE: Few psychosis screening instruments have been tested for use in Africa, yet appropriate tools can increase the detection of self-reported psychotic symptoms, improve the detection of psychosis and impact its prognosis.
METHODS: The construct validity and factor structure of Psychosis Screening Questionnaire (PSQ) were tested with confirmatory factor analysis (CFA) and item response theory (IRT) in a sample of 1928 Ethiopian adults without any history of psychosis. We tested a unidimensional model with and without an item on mania. For IRT, unidimensional latent structure one-parameter logistic (1PL) and two-parameter (2PL) logistic models were tested and compared for relative fit using a likelihood-ratio test.
CONCLUSIONS: The prevalence of lifetime positive screens was 2.8% in an Ethiopian sample of adults from a general medical setting. A unidimensional model demonstrated good fit for the PSQ, (CFI = 0.993, TLI = 0.986 and RMSEA = 0.025). For IRT, a 2PL model was the best fitting one. IRT tests of item difficulty and discrimination parameters showed that paranoia had the highest discrimination α = 4.59 $$ \\left(\\alpha =4.59\\right) $$ and lowest difficulty ( β = 2.53 $$ \\beta =2.53 $$ ), likely to be endorsed at low levels of psychotic features. Thought insertion had the highest item difficulty ( β = 2.98 $$ \\beta =2.98 $$ ). Overall, the measure captures the psychosis construct at higher levels of the latent trait and may be suited for detecting moderate to severe levels of psychosis.
CONCLUSIONS: The PSQ is found to have good construct validity in screening for psychosis among Ethiopian adults. Future studies may focus on the diagnostic validity of the PSQ comparing it with a structured clinical interview.

Schizotypy involves schizophrenia-like traits and symptoms, with the Wisconsin Schizotypy Scales (WSS) being frequently used in previous research. There is some evidence that schizophrenia-spectrum symptom levels, including when using the WSS, might vary both by gender and by race and ethnicity. However, previous research has rarely examined to what extent the WSS show gender and racial bias. Further, this has not been previously examined for the Cognitive Slippage Scale, a measure of disorganized schizotypy. In this study, we examined biases for a subset of items from the WSS in a large sample of undergraduate students (n = 21,829). Using item response theory to test for levels of differential item functioning (DIF), we found some evidence of problematic DIF for all scales, including for negative, positive, and disorganized schizotypy scales. There was evidence of problematic DIF especially by gender and for Black and Multiracial participants. Overall, the current results suggest that gender and/or racial bias on these scales should be an important consideration in using these scales and our results could have implications for assessment of schizophrenia-spectrum symptoms.

BACKGROUND: Suicide was exceptionally high in Hungary in the last century. According to Eurostat, Hungary ranks second in the EU in death by suicide and was among the few countries where the suicidal tendencies increased in 2020. Primary tasks of suicide prevention programs are to develop suicide literacy and dispel myths and misconceptions about suicide. Therefore, the goal of our research was the Hungarian validation of the 26-item Literacy of Suicide Scale (LOSS).
METHODS: 749 people (382 female (51.0%), 364 male (48.6%), 3 identify as non-binary or other (0.4%); 4 identifying as transgender (0.5%)) participated in our online cross-sectional survey with a mean age of 32.4 years (SD = 14.5 years). The H-LOSS questionnaire was adapted using the 2PL (two-parameter logistic) model with WLSE (weighted least squares) estimation in item response theory method, similarly to the original English version.
RESULTS: Scale unidimensionality was confirmed. Model fit indices and internal reliability indicators were acceptable. Item infit and outfit values were adequate, item discrimination values were within range, but one item had extremely high and three items had extremely low item difficulty parameters. Few items had differential item functioning by age, gender and own suidice attempt.
CONCLUSIONS: The H-LOSS scale deemed to be appropriate for assessing suicide literacy in Hungarian speaking samples.

BACKGROUND: Progressive supranuclear palsy (PSP) is a neurodegenerative, late-onset disease that is challenging in terms of assessment. The Progressive Supranuclear Palsy Rating Scale (PSPRS), a 28-item clinician-reported scale, is the most established clinical outcome assessment method. Recently, the U.S. Food and Drug Administration (FDA) has proposed a subscale of 10 items as an alternative to full PSPRS.
OBJECTIVE: To quantitatively evaluate and compare the properties of full PSPRS and the FDA subscale using item response theory. To develop a progression model of the disease and assess relative merits of study designs and analysis options.
METHODS: Data of 979 patients from four interventional trials and two registries were available for analysis. Our investigation was divided into: (1) estimating informativeness of the 28 items; (2) estimating disease progression; and (3) comparing the scales, trial designs, and analysis options with respect to power to detect a clinically relevant treatment effect.
RESULTS: PSPRS item scores had a low pairwise correlation (r = 0.17 ± 0.14) and the items irritability, sleep difficulty, and postural tremor were uncorrelated with the other items. The FDA-selected items displayed higher correlation (r = 0.35 ± 0.14) and were the basis for a longitudinal item response model including disease progression. Trial simulations indicated that identification of a disease-modifying treatment effect required less than half the study size if the analysis was based on longitudinal item information compared with total scores at end-of-treatment.
CONCLUSIONS: A longitudinal item response model based on the FDA-selected PSPRS items is a promising tool in evaluating treatments for PSP. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

BACKGROUND: Current and former athletes are one of the most at-risk population groups for disordered eating (DE), impacting their dietary practices, body composition, performance and health during and following their athletic careers. Few comprehensive DE screening tools exist for this group. To help address this, the current study utilised a mixed-methods approach of Classic Test Theory (CTT) and Item Response Theory (IRT) to develop and validate a DE screening tool suitable for current and former athletes.
METHODS: Novel scale development methodologies were used to develop and assess the validity (content, face, cross-cultural, construct), test-retest reliability, internal consistency reliability, factor analysis and Rasch analysis of a new DE scale.
RESULTS: A new validated Athletic Disordered Eating (ADE) screening tool was created, with 17 items and four subscales (food control, bingeing, body control, body discontent), with an internal consistency reliability of 0.91, excellent content and construct validity, an Intraclass Correlation Coefficient of 0.97 and excellent Rasch model fit.
CONCLUSIONS: The ADE screening tool has been dually developed for research purposes and as a clinically applicable screening tool to detect DE in current and former athletes and is suitable for a global use across sporting categories, diverse genders and levels of competition.