Distinct trajectories of neuropsychiatric symptoms in the 12 months following traumatic brain injury (TBI): a TRACK-TBI study.

BACKGROUND: Neuropsychiatric symptoms are common after traumatic brain injury (TBI) and often resolve within 3 months post-injury. However, the degree to which individual patients follow this course is unknown. We characterized trajectories of neuropsychiatric symptoms over 12 months post-TBI. We hypothesized that a substantial proportion of individuals would display trajectories distinct from the group-average course, with some exhibiting less favorable courses. METHODS: Participants were level 1 trauma center patients with TBI (n = 1943), orthopedic trauma controls (n = 257), and non-injured friend controls (n = 300). Trajectories of six symptom dimensions (Depression, Anxiety, Fear, Sleep, Physical, and Pain) were identified using growth mixture modeling from 2 weeks to 12 months post-injury. RESULTS: Depression, Anxiety, Fear, and Physical symptoms displayed three trajectories: Stable-Low (86.2-88.6%), Worsening (5.6-10.9%), and Improving (2.6-6.4%). Among symptomatic trajectories (Worsening, Improving), lower-severity TBI was associated with higher prevalence of elevated symptoms at 2 weeks that steadily resolved over 12 months compared to all other groups, whereas higher-severity TBI was associated with higher prevalence of symptoms that gradually worsened from 3-12 months. Sleep and Pain displayed more variable recovery courses, and the most common trajectory entailed an average level of problems that remained stable over time (Stable-Average; 46.7-82.6%). Symptomatic Sleep and Pain trajectories (Stable-Average, Improving) were more common in traumatically injured groups. CONCLUSIONS: Findings illustrate the nature and rates of distinct neuropsychiatric symptom trajectories and their relationship to traumatic injuries. Providers may use these results as a referent for gauging typical v. atypical recovery in the first 12 months post-injury.

Linking Rivermead Post Concussion Symptoms Questionnaire (RPQ) and Sport Concussion Assessment Tool (SCAT) scores with item response theory.

OBJECTIVE: Despite the public health burden of traumatic brain injury (TBI) across broader society, most TBI studies have been isolated to a distinct subpopulation. The TBI research literature is fragmented further because often studies of distinct populations have used different assessment procedures and instruments. Addressing calls to harmonize the literature will require tools to link data collected from different instruments that measure the same construct, such as civilian mild traumatic brain injury (mTBI) and sports concussion symptom inventories. METHOD: We used item response theory (IRT) to link scores from the Rivermead Post Concussion Symptoms Questionnaire (RPQ) and the Sport Concussion Assessment Tool (SCAT) symptom checklist, widely used instruments for assessing civilian and sport-related mTBI symptoms, respectively. The sample included data from n = 397 patients who suffered a sports-related concussion, civilian mTBI, orthopedic injury control, or non-athlete control and completed the SCAT and/or RPQ. RESULTS: The results of several analyses supported sufficient unidimensionality to treat the RPQ + SCAT combined item set as measuring a single construct. Fixed-parameter IRT was used to create a cross-walk table that maps RPQ total scores to SCAT symptom severity scores. Linked and observed scores were highly correlated (r = .92). Standard errors of the IRT scores were slightly higher for civilian mTBI patients and orthopedic controls, particularly for RPQ scores linked from the SCAT. CONCLUSION: By linking the RPQ to the SCAT we facilitated efforts to effectively combine samples and harmonize data relating to mTBI.

Parental Enrollment Decision-Making for a Neonatal Clinical Trial.

OBJECTIVE: To describe the parental experience of recruitment and assess differences between parents who participated and those who declined to enroll in a neonatal clinical trial. STUDY DESIGN: This was a survey conducted at 12 US neonatal intensive care units of parents of infants who enrolled in the High-dose Erythropoietin for Asphyxia and encephaLopathy (HEAL) trial or who were eligible but declined enrollment. Questions assessed 6 factors of the parental experience of recruitment: (1) interactions with research staff; (2) the consent experience; (3) perceptions of the study; (4) decisional conflict; (5) reasons for/against participation; and (6) timing of making the enrollment decision. RESULTS: In total, 269 of 387 eligible parents, including 183 of 242 (75.6%) of those who enrolled their children in HEAL and 86 of 145 (59.3%) parents who declined to enroll their children in HEAL, were included in analysis. Parents who declined to enroll more preferred to be approached by clinical team members rather than by research team members (72.9% vs 49.2%, P = .005). Enrolled parents more frequently reported positive initial impressions (54.9% vs 10.5%, P < .001). Many parents in both groups made their decision early in the recruitment process. Considerations of reasons for/against participation differed by enrollment status. CONCLUSIONS: Understanding how parents experience recruitment, and how this differs by enrollment status, may help researchers improve recruitment processes for families and increase enrollment. The parental experience of recruitment varied by enrollment status. These findings can guide future work aiming to inform optimal recruitment strategies for neonatal clinical trials.

To bin or not to bin? A comparison of symptom frequency response formats in the assessment of health-related quality of life.

PURPOSE: The goal of this study is to compare three different types of retrospective frequency response formats on the Healthy Days Symptoms Module (HDSM). Responses are compared in terms of intra-individual consistency, psychometric value, and participant feedback about each type of response format. METHODS: Respondents each completed three versions of the HDSM, where items were framed to elicit an open-ended frequency, a fixed choice frequency, or a vague quantifier response. Traditional reliability statistics were used to evaluate intra-individual consistency. Differential item functioning (DIF) was used to test for response format effects, and item response theory (IRT) scale scores and standard errors were computed across the three forms to compare psychometric value. Linear mixed modeling was used to examine the associations of IRT scale scores across response formats with respondent characteristics. RESULTS: People are largely consistent in how they respond to items about their health, regardless of the response format, and no DIF was detected between response formats. The IRT scores computed from the "# of days" frequency response formats tend to have better measurement precision than those from vague quantifiers. Open-ended frequencies capture a greater span of individual differences for people reporting fewer symptoms; however, little measurement precision is lost in collapsing the frequencies into categories. CONCLUSIONS: Both the open-ended and fixed choice frequency response formats offer more measurement precision than vague quantifiers. While the open-ended frequency response format may capture more individual differences, respondents tend to report more difficulty with exact frequency recall, and thus, prefer the fixed choice frequency format.

Estimating HIV Medication Adherence and Persistence: Two Instruments for Clinical and Research Use.

Antiretroviral therapy (ART) requires lifelong daily oral therapy. While patient characteristics associated with suboptimal ART adherence and persistence have been described in cohorts of HIV-infected persons, these factors are poor predictors of individual medication taking behaviors. We aimed to create and test instruments for the estimation of future ART adherence and persistence for clinical and research applications. Following formative work, a battery of 148 items broadly related to HIV infection and treatment was developed and administered to 181 HIV-infected patients. ART adherence and persistence were assessed using electronic monitoring for 3 months. Perceived confidence in medication taking and self-reported barriers to adherence were strongest in predicting non-adherence over time. Barriers to adherence (e.g., affordability, scheduling) were the strongest predictors of non-adherence, as well as 3- and 7-day non-persistence. A ten-item battery for prediction of these outcomes ( www.med.unc.edu/ncaidstraining/adherence/for-providers ) and a 30-item battery reflective of underlying psychological constructs can help identify and study individuals at risk for suboptimal ART adherence and persistence.

The benefits of adding a brief measure of simple reaction time to the assessment of executive function skills in early childhood.

Early childhood represents a period of rapid cognitive developmental change in executive function (EF) skills along with a variety of related cognitive processes, including processing speed. This leads to interpretational challenges in that children's performance on EF tasks reflects more than EF skills per se. We tested whether the inclusion of a brief measure of simple reaction time (SRT) during EF assessments could help to partially address this challenge. Data were drawn from a cross-sectional convenience sample of 830 preschool-aged children. Individual differences in SRT were significantly associated with performance on all tasks (R2s = .09-.26); slower performance on the SRT task was associated with poorer performance on each EF task. Age-related differences in individual EF tasks were reduced by approximately one half after accounting for age-related differences in SRT, and EF task scores were less coherent (i.e., less strongly intercorrelated with each other) after the removal of SRT. Age-related differences in EF were smaller (Cohen ds = 1.36 vs. 0.78), and poverty-related differences in EF were larger (Cohen ds = 0.30 vs. 0.46) after accounting for SRT-related variation. Finally, consistent with previous studies, SRT-related differences in fluid reasoning were mediated by EF skills. Results are discussed with respect to using a brief measure of SRT to partially address the problem of measurement impurity at the level of individual EF tasks.

Mode effects between computer self-administration and telephone interviewer-administration of the PROMIS(®) pediatric measures, self- and proxy report.

OBJECTIVE: To test equivalence of scores obtained with the PROMIS(®) pediatric Depressive Symptoms, Fatigue, and Mobility measures across two modes of administration: computer self-administration and telephone interviewer-administration. If mode effects are found, to estimate the magnitude and direction of the mode effects. METHODS: Respondents from an internet survey panel completed the child self-report and parent proxy-report versions of the PROMIS(®) pediatric Depressive Symptoms, Fatigue, and Mobility measures using both computer self-administration and telephone interviewer-administration in a crossed counterbalanced design. Pearson correlations and multivariate analysis of variance were used to examine the effects of mode of administration as well as order and form effects. RESULTS: Correlations between scores obtained with the two modes of administration were high. Scores were generally comparable across modes of administration, but there were some small significant effects involving mode of administration; significant differences in scores between the two modes ranged from 1.24 to 4.36 points. CONCLUSIONS: Scores for these pediatric PROMIS measures are generally comparable across modes of administration. Studies planning to use multiple modes (e.g., self-administration and interviewer-administration) should exercise good study design principles to minimize possible confounding effects from mixed modes.

Development and validation of the Proxy-Reported Pulmonary Outcomes Scale for premature infants.

OBJECTIVE: Test the feasibility of using a bedside nurse-reported tool (Proxy-Reported Pulmonary Outcome Scale, PRPOS) for evaluating the severity of bronchopulmonary dysplasia (BPD) by assessing functional, disease-related measures. STUDY DESIGN: Bedside nurses tested the 26-item instrument by observing preterm infants (23-30 weeks at birth) at 36 to 37(4/7) weeks postmenstrual age before, during, and after a care time. We analyzed item reliability, validity, and model fit to determine the six items to include in the final measurement tool. RESULT: We completed assessments on 188 preterm infants. The frequency of an abnormal PRPOS item score increased with increasing National Institute of Child Health and Development (NICHD) BPD category. The six-candidate items produced an internally consistent scale. Addition of the NICHD BPD classification increased reliability moderately; addition of feeding items decreased reliability. The PRPOS score correlated with postmenstrual age at discharge. Infants discharged on oxygen or diuretics had higher median PRPOS scores than did infants who were not prescribed those therapies. CONCLUSION: The PRPOS is an internally consistent, proxy-reported measure of respiratory function in premature infants, based on observable, functional performance measures. Initial testing demonstrates known-groups validity and ongoing testing can assess predictive validity.

Item Response Modeling of Clinical Instruments With Filter Questions: Disentangling Symptom Presence and Severity.

Clinical instruments that use a filter/follow-up response format often produce data with excess zeros, especially when administered to nonclinical samples. When the unidimensional graded response model (GRM) is then fit to these data, parameter estimates and scale scores tend to suggest that the instrument measures individual differences only among individuals with severe levels of the psychopathology. In such scenarios, alternative item response models that explicitly account for excess zeros may be more appropriate. The multivariate hurdle graded response model (MH-GRM), which has been previously proposed for handling zero-inflated questionnaire data, includes two latent variables: susceptibility, which underlies responses to the filter question, and severity, which underlies responses to the follow-up question. Using both simulated and empirical data, the current research shows that compared to unidimensional GRMs, the MH-GRM is better able to capture individual differences across a wider range of psychopathology, and that when unidimensional GRMs are fit to data from questionnaires that include filter questions, individual differences at the lower end of the severity continuum largely go unmeasured. Practical implications are discussed.

Does Response Format Matter? The Psychometric Effects of Filter Questions on Self-Reported Symptom Frequencies.

The presence-severity response format uses a filter question to ask about the presence of a symptom, followed by a question about the severity of that symptom. Only an affirmative response to the filter question triggers the follow-up question. Despite its widespread use, little research has compared the psychometric properties of the presence-severity response format to those of the traditional single-item response format. The purpose of this research was to understand how filter questions influence item responses and characteristics on several short health-related questionnaires. Using two different experimental designs, we find that depending on the construct being measured, the inclusion of a filter question can have a substantial effect on people's responses, and in turn, the psychometric properties of the items. Overall, the presence-severity response format results in a reduction in symptom reporting and loss of information about individual differences, particularly for people experiencing mild symptoms. Measurement recommendations are provided.

Symptom Presence and Symptom Severity as Unique Indicators of Psychopathology: An Application of Multidimensional Zero-Inflated and Hurdle Graded Response Models.

Questionnaires inquiring about psychopathology symptoms often produce data with excess zeros or the equivalent (e.g., none, never, and not at all). This type of zero inflation is especially common in nonclinical samples in which many people do not exhibit psychopathology, and if unaccounted for, can result in biased parameter estimates when fitting latent variable models. In the present research, we adopt a maximum likelihood approach in fitting multidimensional zero-inflated and hurdle graded response models to data from a psychological distress measure. These models include two latent variables: susceptibility, which relates to the probability of endorsing the symptom at all, and severity, which relates to the frequency of the symptom, given its presence. After estimating model parameters, we compute susceptibility and severity scale scores and include them as explanatory variables in modeling health-related criterion measures (e.g., suicide attempts, diagnosis of major depressive disorder). Results indicate that susceptibility and severity uniquely and differentially predict other health outcomes, which suggests that symptom presence and symptom severity are unique indicators of psychopathology and both may be clinically useful. Psychometric and clinical implications are discussed, including scale score reliability.

A multidimensional zero-inflated graded response model for ordinal symptom data.

Zero responses and their equivalents-for example, never, none, not at all-are commonly observed on measures of psychopathology inquiring about symptom frequencies, particularly when these measures are administered to community samples. Measurement researchers typically accommodate multivariate zero inflation by including a nonpathological class of respondents who endorse zero for all symptoms. While this latent class approach accounts for test-level zero inflation (i.e., a proportion of individuals who do not experience any of the symptoms), it may be overly restrictive on questionnaires comprising items of differing severity. For example, an item about suicidal ideation is likely to exhibit a much higher degree of zero inflation than an item about low energy. Existing models do not account for this variability. We propose a multidimensional zero-inflated graded response model (MZI-GRM) as a more flexible approach for modeling zero inflation on questionnaires. According to the model, two distinct but correlated latent variables underlie ordinal item responses; one represents susceptibility to the construct, whereas the other represents severity. As a motivating example, we show how the MZI-GRM can be fit to data from the PHQ-9, a common depression screener. Results suggest that the MZI-GRM is better able to capture zero inflation across items than existing alternative models. Further, we find support for a multidimensional model that allows distinct but correlated latent variables to underlie each response process. Some items better measure susceptibility to depression (symptom presence), whereas others better capture severity of depression (symptom frequency). Implications for scale development and scoring are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

How Do Scores on the Functional Status Examination (FSE) Correspond to Scores on the Glasgow Outcome Scale-Extended (GOSE)?

This study was designed to determine how raw scores correspond between two alternative measures of functional recovery from traumatic brain injury (TBI), the Functional Status Examination (FSE) and the Glasgow Outcome Scale-Extended (GOSE). Using data from 357 persons with moderate-severe TBI who participated in a large clinical trial, we performed item response theory analysis to characterize the relationship between functional ability measured by the FSE and GOSE at 6 months post-injury. Results revealed that raw scores for the FSE and GOSE can be linked, and a table is provided to translate scores from one instrument to the other. For example, a FSE score of 7 (on its 0-21 scale, where higher scores reflect more impairment) is equivalent to a GOSE score of 6 (where GOSE is scaled on an 8-point scale, with higher scores reflecting less impairment). These results allow clinicians or researchers who have a score for a person on one instrument to cross-reference it to a score on the other instrument. Importantly, this enables researchers to combine data sets where some persons only completed the GOSE and some only the FSE. In addition, an investigator could save participant time by eliminating one instrument from a battery of tests, yet still retain a score on that instrument for each participant. More broadly, the findings help anchor scores from these two instruments to the broader continuum of injury-related functional limitations.

Improving the Precision of the Glasgow Outcome Scale-Extended Using Item Response Theory: A TRACK-TBI Study.

The Glasgow Outcome Scale-Extended (GOSE) is a functional outcome measure intended to place individuals with traumatic brain injury (TBI) into one of eight broad levels of injury-related disability. This simplicity is not always optimal, particularly when more granular assessment of individuals' injury recovery is desired. The GOSE, however, is customarily assessed using a multi-question interview that contains richer information than is reflected in the GOSE score. Using data from the multi-center Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study (N = 1544), we used item response theory (IRT) to evaluate whether rescoring the GOSE using IRT, which posits that a continuous latent variable (disability) underlies responses, can yield a more precise index of injury-related functional limitations. We fit IRT models to GOSE interview responses collected at three months post-injury. Each participant's level of functional limitation was estimated from the model (GOSE-IRT) and comparisons were made between IRT-based and standard (GOSE-Ordinal) scores. The IRT scoring resulted in 141 possible scores (vs. 7 GOSE-Ordinal scores in this sample of individuals with GOSE scores ranging between 2 and 8). Moreover, GOSE-IRT scores were significantly more strongly associated with measures of TBI-related symptoms, psychological symptoms, and quality of life. Our findings demonstrate that rescoring the GOSE interview using IRT yields more granular, meaningful measurement of injury-related functional limitations, while adding no additional respondent or examiner burden. This technique may have utility for many applications, such as clinical trials aiming to detect small treatment effects, and small-scale studies that need to maximize statistical efficiency.

Differential Item Functioning Based on Autism Features, IQ, and Age on the Screen for Child Anxiety Related Disorders (SCARED) Among Youth on the Autism Spectrum.

Anxiety commonly occurs among youth on the autism spectrum, yet measurement of anxiety in this population is complicated by a number of factors, including potentially overlapping symptomatology, the child's intellectual functioning, and changes in anxiety across development. Moreover, few studies have examined the psychometric properties of anxiety measures in this population, and no study to date has tested whether there are systematic differences in the measurement of anxiety, or differential item functioning (DIF), across the high degree of heterogeneity and the developmental course of autism. To test this possibility, data were combined across multiple studies using the National Database for Autism Research, an NIH-funded data repository. Parent-report on the Screen for Child Anxiety Related Disorders (SCARED) and Social Communication Questionnaire (SCQ) were used as measures of anxiety and autism features, respectively. A confirmatory factor analysis indicated good fit of the literature standard five-factor structure. Moderated nonlinear factor analysis (MNLFA) revealed multiple items with intercept and loading DIF based on level of autism features, IQ, and age, especially for items related to social behavior. Therefore, although the measure's factor structure is consistent with that found in the general population, the SCARED may not capture differences in anxiety equivalently for all children on the spectrum and across their development. Clinicians and researchers need to be especially vigilant in measuring anxiety symptoms in children with autism by removing items flagged for DIF from the SCARED and/or by using multiple measures and informants. LAY ABSTRACT: Autistic youth often experience clinical levels of anxiety. Many tools used to measure anxiety were developed for the general population, but not for use with autistic youth. This study found that the Screen for Child Anxiety Related Disorders (SCARED) measures the same five dimensions of anxiety as in the general population. Parents, however, may respond differently to questions on the SCARED based on their child's autism features, intellectual functioning, and age, which impacts our ability to accurately measure anxiety among autistic youth.

Functional Status Examination Yields Higher Measurement Precision than the Glasgow Outcome Scale-Extended after Moderate-to-Severe Traumatic Brain Injury.

A limited evidence base supports the Functional Status Examination (FSE) as superior to the more commonly used Glasgow Outcome Scale-Extended (GOSE) for precisely characterizing injury-related functional limitations. The aim of this study was to use modern psychometric tools to test the hypothesis that the FSE is more precise than the GOSE in characterizing individual differences in functional limitations after moderate-to-severe traumatic brain injury (TBI). Secondarily, we sought to confirm that the type of interviewee (patient, significant other) does not affect the test performance of the FSE. Using data from 357 individuals with TBI who participated in the Magnesium Sulfate clinical trial and had six-month outcome data, we performed item response theory (IRT) analyses comparing the FSE and GOSE at six months post-injury. Results showed that the FSE yielded higher measurement precision (IRT test information) than the GOSE across most of the disability severity spectrum. The GOSE yielded more information than the FSE at a very high level of disability, because of the GOSE's assignment of a unique score for individuals who are in a vegetative state. Finally, the FSE showed no evidence of differential item functioning by interviewee, indicating it is appropriate to interview either persons with TBI or significant others and combine data across respondents as is typically done. The findings support the FSE as a viable and oftentimes advantageous substitute for the GOSE in clinical trials and translational studies of TBI.

A Psychometric Analysis of the Social Anxiety Scale for Adolescents Among Youth With Autism Spectrum Disorder: Caregiver-Adolescent Agreement, Factor Structure, and Validity.

Social anxiety is common among adolescents with autism spectrum disorder (ASD). An ongoing challenge for both research and clinical practice in ASD is the assessment of anxious symptomatology. Despite its widespread use in samples of youth with ASD, the Social Anxiety Scale for Adolescents (SAS-A) has not received psychometric evaluation within this population; thus, the validity of its use in research and clinical practice for ASD remains unclear. The present study conducted a psychometric analysis of caregiver and adolescent SAS-A forms in a sample of adolescents with ASD (N = 197). Results revealed (1) poor caregiver-adolescent item-level agreement, (2) a two-factor structure, (3) lack of measurement invariance between reporters, and (4) modest evidence for convergent and discriminant validity. Overall, findings suggest that this measure demonstrates reasonable psychometric properties in an ASD sample. Lack of measurement invariance, however, calls for careful interpretation of research involving the SAS-A in ASD samples, particularly when the primary goal is to compare adolescent and caregiver reports. The implications of these findings for future research and clinical practice are discussed.

Parental Factors Associated With the Decision to Participate in a Neonatal Clinical Trial.

Importance: It remains poorly understood how parents decide whether to enroll a child in a neonatal clinical trial. This is particularly true for parents from racial or ethnic minority populations. Understanding factors associated with enrollment decisions may improve recruitment processes for families, increase enrollment rates, and decrease disparities in research participation. Objective: To assess differences in parental factors between parents who enrolled their infant and those who declined enrollment for a neonatal randomized clinical trial. Design, Setting, and Participants: This survey study conducted from July 2017 to October 2019 in 12 US level 3 and 4 neonatal intensive care units included parents of infants who enrolled in the High-dose Erythropoietin for Asphyxia and Encephalopathy (HEAL) trial or who were eligible but declined enrollment. Data were analyzed October 2019 through July 2020. Exposure: Parental choice of enrollment in neonatal clinical trial. Main Outcomes and Measures: Percentages and odds ratios (ORs) of parent participation as categorized by demographic characteristics, self-assessment of child's medical condition, study comprehension, and trust in medical researchers. Survey questions were based on the hypothesis that parents who enrolled their infant in HEAL differ from those who declined enrollment across 4 categories: (1) infant characteristics and parental demographic characteristics, (2) perception of infant's illness, (3) study comprehension, and (4) trust in clinicians and researchers. Results: Of a total 387 eligible parents, 269 (69.5%) completed the survey and were included in analysis. This included 183 of 242 (75.6%) of HEAL-enrolled and 86 of 145 (59.3%) of HEAL-declined parents. Parents who enrolled their infant had lower rates of Medicaid participation (74 [41.1%] vs 47 [55.3%]; P = .04) and higher rates of annual income greater than $55 000 (94 [52.8%] vs 30 [37.5%]; P = .03) compared with those who declined. Black parents had lower enrollment rates compared with White parents (OR, 0.35; 95% CI, 0.17-0.73). Parents who reported their infant's medical condition as more serious had higher enrollment rates (OR, 5.7; 95% CI, 2.0-16.3). Parents who enrolled their infant reported higher trust in medical researchers compared with parents who declined (mean [SD] difference, 5.3 [0.3-10.3]). There was no association between study comprehension and enrollment. Conclusions and Relevance: In this study, the following factors were associated with neonatal clinical trial enrollment: demographic characteristics (ie, race/ethnicity, Medicaid status, and reported income), perception of illness, and trust in medical researchers. Future work to confirm these findings and explore the reasons behind them may lead to strategies for better engaging underrepresented groups in neonatal clinical research to reduce enrollment disparities.

Preliminary Validation of an Abbreviated Acute Concussion Symptom Checklist Using Item Response Theory.

BACKGROUND: Symptom assessment is a critical component of concussion diagnosis and management, with item selection primarily driven by clinical judgment or expert consensus. We recently demonstrated that concussion symptoms assessed by the Sport Concussion Assessment Tool (SCAT) are essentially unidimensional, implying that overall symptom severity may be accurately estimated with relatively few questions. Briefer, evidence-based forms for symptom assessment would provide clinicians flexibility. PURPOSE: To develop and validate an abbreviated assessment of general concussion symptom severity using item response theory analyses. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Broad clinical assessments (SCAT3, Immediate Post-concussion and Cognitive Testing, Balance Error Scoring System, and Brief Symptom Inventory-18 Global Severity Index) were completed by 265 injured athletes and 235 matched teammate controls at 24 to 48 hours and 8, 15, and 45 days after concussion. Symptom checklist short forms (3-14 items from the original 22) were selected using item response theory item information curves. Internal consistency reliability (Cronbach alpha), correlation with criterion measures assessed concurrently (ie, acute neurocognitive performance, balance, and emotional symptoms), predictive validity (correlations with symptom duration), and differences between concussed and control groups (Cohen d) were examined across forms. Sensitivity and false-positive rates of the forms were estimated and compared using reliable change indices derived from controls. RESULTS: Across the 3- to 22-item forms, internal consistency was excellent (Cronbach alphas, 0.90-0.94). Clinical correlations were significant (P≤ .017) and to similar degrees for all short forms. Group difference confidence intervals overlapped across forms at 24- to 48-hour (Cohen d, 1.27-1.51) and 8-day follow-up (Cohen d, 0.31-0.44). Sensitivity remained similar across short forms, with a low false-positive rate in controls. CONCLUSION: Our findings suggest that even an ultrashort (3-item) inventory provides sufficiently reliable and valid estimates of overall concussion symptom severity 24 to 48 hours after injury. Future revisions of the SCAT could eliminate inefficient items, although replication in larger samples and extension to other postinjury time points are warranted.