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The development of a brief screener for autism using item response theory.

ABSTRACT: BACKGROUND:Brief screening instruments focusing on autism spectrum disorder (ASD) that can be administered in primary care are scarce; there is a need for shorter and more precise instruments. The Autism-Tics, AD/HD and other Comorbidities inventory (A-TAC) has previously been validated for ASD reporting excellent validity. This study aims to determine the psychometric properties of each item in the ASD domain (17 items) in the A-TAC using item response theory (IRT), and thereby construct and validate a short form that could be used as a screening instrument in the general population. METHODS:Since 2004, parents of all 9-year-old Swedish twins have been invited to participate in a telephone interview in the Child and Adolescent Twin Study in Sweden (CATSS). The CATSS is linked to the National Patient Register (NPR), which includes data from in- and outpatient care. Data on ASD (A-TAC) collected in CATSS were compared with diagnoses from the NPR. Diagnoses that had been made both before (previous validity) and after (predictive validity) the interviews were included. The sample was divided into a developmental sample and a validation sample. An IRT model was fitted to the developmental sample and item parameters were used to select a subset of items for the short form. The performance of the proposed short form was examined in the validation sample by the use of receiver operation characteristic curves. RESULTS:Four items which were able to discriminate among individuals with more autism traits were deemed sufficient for use in the short form. The values of the area under the receiver operating characteristic curve for a clinical diagnosis of ASD was .95 (previous validity) and .72 (predictive validity). CONCLUSIONS:The proposed short form with 4 out of the original 17 items from A-TAC, showed excellent previous validity while the predictive validity was fair. The validity of the short form was in agreement with previous validations of the full ASD domain. The short form can be a valuable screening instrument in primary care settings in order to identify individuals in need for further assessment and for use in epidemiological studies.

SUBMITTER: Marland C

PROVIDER: S-EPMC6829932 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Allostatic load is commonly operationalized using a sum-score of high-risk biomarkers. However, this method implies that biomarkers contribute equally to allostatic load, as each is given equal weight. Our goal in this methodological paper is to evaluate this, and complementarily, to identify biomarkers that are most informative and least informative for developing an allostatic load index. Item response theory models provide an alternate approach to calculating the allostatic load score, by treating individual biomarkers (e.g. “items”) as indicators of a latent allostatic load construct. Item response theory scores account for the data-driven discriminating power of each biomarker, and an individual’s pattern of biomarker responses. To demonstrate feasibility of this approach, we used data from the 2015–2016 National Health Examination and Nutrition Survey (NHANES; N = 3751), with twelve allostatic load biomarkers representing immune response, metabolic function and cardiovascular health. Item response theory models revealed that body-mass-index and C-reactive protein were the most informative biomarkers for allostatic load. Both higher allostatic load sum-score and allostatic load item response theory score were associated with lower socio-economic status (p = 0.008; p<0.001, respectively). Further, both formulations of allostatic load were positively associated with a nine-item depression screener (p<0.001 for both), but only the item response theory score was also positively associated with the impact of depressive symptoms on daily life (p = 0.045). Item response theory scores may be more finely tuned to tease out effects, compared to sum-scores, and also provide more flexibility when there are missing biomarker measurements. Supplemental R code for our approach are included. Highlights • Methodological paper to introduce item response theory for calculating allostatic load.• Biomarker data from NHANES 2015–2016 representative of United States adults.• Body-mass-index and C-reactive protein most informative for allostatic load.• Item response theory captures more variability in allostatic load compared to sum-scores.• Future work - item response theory can standardize allostatic load across datasets.

Project description:Although many interventions and services for autistic people have the ultimate goal of improving quality of life (QoL), there is relatively little research on how best to assess this construct in the autistic population, and existing scales designed for non-autistic individuals may not assess all meaningful facets of QoL in the autistic population. To address this need, the autism spectrum QoL form (ASQoL) was recently developed as a measure of the autism-relevant quality of life. However, the psychometrics of the ASQoL have not been examined beyond the authors' initial validation study, and important properties such as measurement invariance/differential item functioning (DIF) have not yet been tested. Using data from 700 autistic adults recruited from the Simons Foundation's SPARK cohort, the current study sought to perform a comprehensive independent psychometric evaluation of the ASQoL using item response theory, comparing its performance to a newly-proposed brief measure of general QoL (the WHOQOL-4). Our models revealed substantial DIF by sex and gender in the ASQoL, which caused ASQoL scores to grossly underestimate the self-reported QoL of autistic women. Based on a comparison of latent variable means, we demonstrated that observed sex/gender differences in manifest ASQoL scores were the result of statistical artifacts, a claim that was further supported by the lack of significant group differences on the sex/gender-invariant WHOQOL-4. Our findings indicate that the ASQoL composite score is psychometrically problematic in its current form, and substantial revisions may be necessary before valid and meaningful inferences can be made regarding autism-relevant aspects of QoL. LAY SUMMARY: Quality of life (QoL) is an extremely important outcome for autistic people, but many of the tools that are used to measure it does not take into account how QoL may be different for autistic people. Using data from 700 autistic adults, we examined the measurement properties of the autism spectrum quality of life form (ASQoL), a new measure of QoL designed specifically for autistic people. Our results indicate that the ASQoL shows a pronounced sex/gender bias, which causes it to underestimate QoL in autistic women. This bias needs to be eliminated before the ASQoL can be successfully used to measure QoL in the autistic population.

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The development of a brief screener for autism using item response theory.

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