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Objective: To derive and validate a brief patient-completed instrument, the Lupus Impact Tracker (LIT), to assess and monitor the impact of systemic lupus erythematosus (SLE)., Methods: Items for the LIT were selected from the LupusPRO, a validated patient-reported outcomes measure, using 3 approaches: confirmatory factor analysis (CFA), stepwise regression, and patient focus groups. CFA was conducted to find items from the LupusPRO that fit a unidimensional structure to allow scoring as a single index. Stepwise regression methods identified items with the strongest relationship (convergent validity) with disease activity measures and patient health rating. Focus groups (n = 26 patients) identified the most important items describing SLE impact. Selected items were evaluated for reliability and validity., Results: CFA found 21 items that fit a unidimensional structure. Stepwise regressions identified 15 of 21 items having good convergent validity with clinical measures. Patient focus groups identified 9 of 15 items as best capturing the impact of SLE. Overall, 7 items were selected across all 3 approaches (CFA, stepwise regression, and focus groups). Another 15 items were selected across 2 approaches. Through consensus with rheumatology clinician experts, a final set of 10 items was selected for the LIT. The LIT items showed good internal consistency (0.89) and test-retest reliabilities (0.87). Mean LIT scores differed significantly (P < 0.05) across criterion groups in the hypothesized direction, providing evidence of discriminant validity and responsiveness., Conclusion: The LIT is reliable and valid in SLE patients and offers a practical way for physicians and patients to assess and monitor the impact of SLE., (Copyright © 2014 by the American College of Rheumatology.)

Objective: To evaluate the psychometric properties of the Glaucoma Symptom Identifier (GSI), a tool designed to assess multiple possible glaucoma symptoms and their impact on quality of life in clinical practice. We sought to address the need for better methods to assess visual function related to quality of life of glaucoma patients with a tool to show to both physicians and their patients that glaucoma is not an asymptomatic disease. The development process was to provide comprehensive assessment in 1 page of the impact of glaucoma on patients' quality of life by including an exhaustive list of unique and nonredundant items., Design: Cross-sectional online survey., Participants: Seven hundred and eighteen individuals with a self-reported diagnosis of glaucoma, who were at least 40 years of age., Methods: The impact of glaucoma was assessed by asking study participants the degree of difficulty they experience on a number of tasks. Item response theory was used to psychometrically evaluate the GSI. Scores on the GSI and the SF-12, a generic quality-of-life instrument, were compared., Main Outcome Measures: Items in the GSI were categorized in terms of their ability to capture glaucoma impact on quality of life across the population range of subjects from mild-to-severe glaucoma severity., Results: The GSI showed good reliability, and convergent and discriminant validity. Items in the GSI captured glaucoma impact on quality of life over an adequate range of disease severity. Potential improvements to the existing questionnaire were identified using item response theory modeling results and respondents' feedback on the survey., Conclusions: Our findings suggest that the GSI is a psychometrically valid tool, adequate for glaucoma patients' self-administration within a clinician's routine practice to help both the patient and physician assess the patient's current and potential future symptoms of glaucoma.

Objective: To provide additional validity data for the Asthma Control TestTM (ACT) using a different criterion measure, setting, and population., Study Design: Cross-sectional survey., Methods: Questionnaires were completed at home by a random sample of 570 members of a large integrated healthcare organization who were 35 years or older with utilization suggestive of active asthma. The questionnaires included the ACT; another validated asthma control questionnaire (Asthma Therapy Assessment Questionnaire [ATAQ]), which was used as the criterion measure; a validated quality-of-life tool (Mini Asthma Quality of Life Questionnaire [Mini-AQLQ]); a validated symptom frequency scale (Asthma Outcomes Monitoring System); and information regarding demographics., Results: The ACT score was statistically significantly correlated with findings on the ATAQ (P = -0.73), Mini-AQLQ (P = 0.77), and symptom frequency scale (P = -0.69). The optimal ACT cutoff for well-controlled asthma (ATAQ level, 0) was confirmed to be 20 or higher (sensitivity, 78.1%; specificity, 83.8%), and the optimal ACT cutoff for poorly controlled asthma (ATAQ level, 3-4) was confirmed to be 15 or lower (sensitivity, 90.4%; specificity, 80.9%)., Conclusion: These data further support the validity of the ACT in the home setting among a random sample of patients with asthma.

Objective: To compare the measurement properties of the Modified Health Assessment Questionnaire [MHAQ], the SF-36((R)) Health Survey 10 item Physical Functioning scale [PF10], and scores from an item response theory (IRT) based scale combining the two measures., Study Design: Rheumatoid arthritis (RA) patients (n = 339) enrolled in a multi-center, randomized, double-blind, placebo-controlled trial completed the MHAQ and the SF-36 pre- and post-treatment. Psychometric analyses used confirmatory factor analysis and IRT models. Analyses of variance were used to assess sensitivity to changes in disease severity (defined by the American College of Rheumatism (ACR)) using change scores in MHAQ, PF10, and IRT scales. Analyses of covariance were used to assess treatment responsiveness., Results: For the entire score range, the 95% confidence interval around individual patient scores was smaller for the combined (total) IRT based scale than for other measures. The MHAQ and PF10 were about 70% and 50% as efficient as the total IRT score of physical functioning in discriminating among ACR groups, respectively. The MHAQ and PF10 were also less efficient than the total IRT score in discriminating among treatment groups., Conclusions: Combining scales from the two short forms yields a more powerful tool with greater sensitivity to treatment response.

Background: Migraine and other severe headaches can cause suffering and reduce functioning and productivity. Patients are the best source of information about such impact., Objective: To develop a new short form (HIT-6) for assessing the impact of headaches that has broad content coverage but is brief as well as reliable and valid enough to use in screening and monitoring patients in clinical research and practice., Methods: HIT-6 items were selected from an existing item pool of 54 items and from 35 items suggested by clinicians. Items were selected and modified based on content validity, item response theory (IRT) information functions, item internal consistency, distributions of scores, clinical validity, and linguistic analyses. The HIT-6 was evaluated in an Internet-based survey of headache sufferers (n = 1103) who were members of America Online (AOL). After 14 days, 540 participated in a follow-up survey., Results: HIT-6 covers six content categories represented in widely used surveys of headache impact. Internal consistency, alternate forms, and test-retest reliability estimates of HIT-6 were 0.89, 0.90, and 0.80, respectively. Individual patient score confidence intervals (95%) of app. +/-5 were observed for 88% of all respondents. In tests of validity in discriminating across diagnostic and headache severity groups, relative validity (RV) coefficients of 0.82 and 1.00 were observed for HIT-6, in comparison with the Total Score. Patient-level classifications based in HIT-6 were accurate 88.7% of the time at the recommended cut-off score for a probability of migraine diagnosis. HIT-6 was responsive to self-reported changes in headache impact., Conclusions: The IRT model estimated for a 'pool' of items from widely used measures of headache impact was useful in constructing an efficient, reliable, and valid 'static' short form (HIT-6) for use in screening and monitoring patient outcomes.

Background: While item response theory (IRT) offers many theoretical advantages over classical test theory in the construction and scoring of patient based measures of health few studies compare scales constructed from both methodologies head to head., Objective: Compare the responsiveness to treatment of migraine specific scales scored using summated rating scale methods vs. IRT methods., Methods: The data came from three clinical studies of migraine treatment that used the Migraine Specific Quality of Life Questionnaire (MSQ). Five methods of quantifying responsiveness were used to evaluate and compare changes from pre- to post-treatment in MSQ scales scored using Likert and IRT scaling methods., Results: Changes in all MSQ scale scores from pre- to post-treatment were highly significant in all three studies. A single index scored from the MSQ using IRT methods was determined to be more responsive than any one of the MSQ subscales across the five methods used to quantify responsiveness. Across 13 of the 15 tests (5 responsiveness methods * 3 studies) conducted, the single index scored from the MSQ using IRT methods was the most responsive measure., Conclusions: IRT methods increased the responsiveness of the MSQ to the treatment of migraine. The results agree with the psychometric evidence that suggest that it is feasible to score a single index from the MSQ using IRT methods. This approach warrants further testing with other measures of migraine impact.

Background: Measurement of headache impact is important in clinical trials, case detection, and the clinical monitoring of patients. Computerized adaptive testing (CAT) of headache impact has potential advantages over traditional fixed-length tests in terms of precision, relevance, real-time quality control and flexibility., Objective: To develop an item pool that can be used for a computerized adaptive test of headache impact., Methods: We analyzed responses to four well-known tests of headache impact from a population-based sample of recent headache sufferers (n = 1016). We used confirmatory factor analysis for categorical data and analyses based on item response theory (IRT)., Results: In factor analyses, we found very high correlations between the factors hypothesized by the original test constructers, both within and between the original questionnaires. These results suggest that a single score of headache impact is sufficient. We established a pool of 47 items which fitted the generalized partial credit IRT model. By simulating a computerized adaptive health test we showed that an adaptive test of only five items had a very high concordance with the score based on all items and that different worst-case item selection scenarios did not lead to bias., Conclusion: We have established a headache impact item pool that can be used in CAT of headache impact.

Background: Item response theory (IRT) is a powerful framework for analyzing multiitem scales and is central to the implementation of computerized adaptive testing., Objectives: To explain the use of IRT to examine measurement properties and to apply IRT to a questionnaire for measuring migraine impact--the Migraine Specific Questionnaire (MSQ)., Methods: Data from three clinical studies that employed the MSQ-version 1 were analyzed by confirmatory factor analysis for categorical data and by IRT modeling., Results: Confirmatory factor analyses showed very high correlations between the factors hypothesized by the original test constructions. Further, high item loadings on one common factor suggest that migraine impact may be adequately assessed by only one score. IRT analyses of the MSQ were feasible and provided several suggestions as to how to improve the items and in particular the response choices. Out of 15 items, 13 showed adequate fit to the IRT model. In general, IRT scores were strongly associated with the scores proposed by the original test developers and with the total item sum score. Analysis of response consistency showed that more than 90% of the patients answered consistently according to a unidimensional IRT model. For the remaining patients, scores on the dimension of emotional function were less strongly related to the overall IRT scores that mainly reflected role limitations. Such response patterns can be detected easily using response consistency indices. Analysis of test precision across score levels revealed that the MSQ was most precise at one standard deviation worse than the mean impact level for migraine patients that are not in treatment. Thus, gains in test precision can be achieved by developing items aimed at less severe levels of migraine impact., Conclusions: IRT proved useful for analyzing the MSQ. The approach warrants further testing in a more comprehensive item pool for headache impact that would enable computerized adaptive testing.

Objective: To evaluate the feasibility of computerized adaptive testing (CAT) and the reliability and validity of CAT-based estimates of headache impact scores in comparison with 'static' surveys., Methods: Responses to the 54-item Headache Impact Test (HIT) were re-analyzed for recent headache sufferers (n = 1016) who completed telephone interviews during the National Survey of Headache Impact (NSHI). Item response theory (IRT) calibrations and the computerized dynamic health assessment (DYNHA) software were used to simulate CAT assessments by selecting the most informative items for each person and estimating impact scores according to pre-set precision standards (CAT-HIT). Results were compared with IRT estimates based on all items (total-HIT), computerized 6-item dynamic estimates (CAT-HIT-6), and a developmental version of a 'static' 6-item form (HIT-6-D). Analyses focused on: respondent burden (survey length and administration time), score distributions ('ceiling' and 'floor' effects), reliability and standard errors, and clinical validity (diagnosis, level of severity). A random sample (n = 245) was re-assessed to test responsiveness. A second study (n = 1103) compared actual CAT surveys and an improved 'static' HIT-6 among current headache sufferers sampled on the Internet. Respondents completed measures from the first study and the generic SF-8 Health Survey; some (n = 540) were re-tested on the Internet after 2 weeks., Results: In the first study, simulated CAT-HIT and total-HIT scores were highly correlated (r = 0.92) without 'ceiling' or 'floor' effects and with a substantial reduction (90.8%) in respondent burden. Six of the 54 items accounted for the great majority of item administrations (3603/5028, 77.6%). CAT-HIT reliability estimates were very high (0.975-0.992) in the range where 95% of respondents scored, and relative validity (RV) coefficients were high for diagnosis (RV = 0.87) and severity (RV = 0.89); patient-level classifications were accurate 91.3% for a diagnosis of migraine. For all three criteria of change, CAT-HIT scores were more responsive than all other measures. In the second study, estimates of respondent burden, item usage, reliability and clinical validity were replicated. The test-retest reliability of CAT-HIT was 0.79 and alternate forms coefficients ranged from 0.85 to 0.91. All correlations with the generic SF-8 were negative., Conclusions: CAT-based administrations of headache impact items achieved very large reductions in respondent burden without compromising validity for purposes of patient screening or monitoring changes in headache impact over time. IRT models and CAT-based dynamic health assessments warrant testing among patients with other conditions.

Background: Migraine headaches have been shown to have substantial personal and societal implications. Health-related quality of life (HRQOL) assessments of migraineurs have been used to monitor and evaluate patient- and population-based outcomes, and to evaluate effectiveness and responsiveness to treatment. In this paper, we test a new, even shorter generic health survey, the SF-8 Health Survey (SF-8), an alternate form that uses one question to measure each of the eight SF-36 Health Survey (SF-36) domains, in a sub-sample of migraine sufferers., Methods: Data from 7557 participants surveyed via the Internet and mail were used to document the burden of migraine on HRQOL and to compare the relative burden of migraine with other chronic conditions using the SF-8., Results: Migraineurs' HRQOL is similar to those with congestive heart failure, hypertension and diabetes, and is better than those with depression. Migraine sufferers experience better physical health and worse mental health (MH) than those with osteoarthritis. Results support prior research indicating that the burden of migraine on functional health and well-being is considerable and comparable to other chronic conditions known to have substantial impact on HRQOL., Conclusions: The SF-8 may provide a more practical and efficient method to describe the burden of migraine in population studies.

Background: Item response theory (IRT) scoring of health status questionnaires offers many advantages. However, to ensure 'backwards comparability' and to facilitate interpretations of results, we need the ability to express the IRT score in the metrics of the traditional scales., Objectives: To develop procedures to calibrate IRT-based scores on the Headache Impact Test (HIT) into the metrics of the traditional headache scales. To assess the degree to which the calibrated HIT scores agree with the observed traditional scores and lead to the same conclusions in group comparisons., Methods: We used telephone interview data (n = 1016) and Internet data (n = 1103) from general population surveys of recent headache sufferers. Analyses were conducted in four steps: (1) develop IRT models for all items, (2) for each IRT score level, calculate the expected score on each of the traditional scales (calibration), (3) adjust this calibrated score for measurement error in the IRT score, (4) for each of the traditional scales, assess agreement between calibrated HIT scores and observed scores using intraclass correlation (ICC) and evaluate the agreement of mean scores and the relative validity (RV) in discriminating among groups differing in migraine diagnosis, headache severity, and change in impact over time., Results: For the traditional categorical questionnaire items (the Migraine Specific Questionnaire (MSQ) and the Headache Disability Inventory (HDI)) the calibrated HIT agreed with the observed traditional scores: ICC's were between 0.80 and 0.94. In RV analyses the maximum mean difference between the observed and expected scores was 1.7 points on a 0-100 scale for comparisons at one point in time. Analyses of change over time and analyses calibrating scores from the fixed-form HIT-6 to the metric of other questionnaires were also satisfactory although less precise. Analysis of non-standard questionnaire items (e.g. On how many days in the past 3 months did you have a headache, from the HIMQ and the MIDAS) required special IRT models. Agreement was less good: ICC's were between 0.56 and 0.61 and the maximum mean differences were 2.9 (on a 0-270 scale) and 3.8 (on a 0-450 scale) in RV analyses at one point in time. The ability of the calibrated scale scores to discriminate between groups was at least as good as the ability of the observed sum scales and often remarkably better., Conclusion: The theoretical advantage of IRT models in scale calibration is supported by our results. This approach to achieving comparability of new and widely-used scales and accelerating the accumulation of interpretation guidelines based on previous work warrant testing for measures of other generic and disease-specific concepts.

Objective: To document the burden of early rheumatoid arthritis (RA) on health-related quality of life (HQL) and compare changes in HQL across 2 treatments., Study Design: Analysis of HQL scores among patients enrolled in a multicenter, double-blind, randomized control trial of early RA treatment., Patients and Methods: A total of 424 patients with early RA were randomized to 1 of 2 treatment groups: etanercept or methotrexate. Patients were treated and followed for 52 weeks. Health-related quality of life was assessed before and throughout treatment using the Medical Outcomes Study Short Form 36 Health Survey (SF-36) and the Health Assessment Questionnaire (HAQ). The HQL burden of RA was established by comparing SF-36 scale scores to general US population norms. The impact of treatment on HQL was determined by comparing scores on both SF-36 and HAQ scales., Results: Before treatment, RA patients showed significant decrements in scores on all SF-36 scales and summary measures in comparison with age- and sex-matched general US population norms, multivariate analysis of variance (MANOVA) F(8,2815) = 204.6, P < .0001. After 52 weeks of treatment, 7 of 8 SF-36 scales and the physical summary measure remained significantly below the general US population norm, MANOVA F(8,2815) = 41.9, P < .0001. Patients randomized to etanercept showed significantly better HQL improvement earlier in treatment than patients randomized to methotrexate on the SF-36 physical summary, MANOVA F(10,4230) = 6.1, P< .0001, the SF-36 arthritis-specific health index, MANOVA F(10,4230) = 8.5, P < .0001, and the HAQ, MANOVA F(10,4230) = 14.7, P < .0001. At 52 weeks, there were no significant differences between treatment groups., Conclusions: Rheumatoid arthritis places tremendous disease burden on patients' HQL. Successful treatment of early RA improved HQL. Etanercept showed a rapid HQL response.

Objective: To define clinically meaningful changes in 2 widely used health-related quality of life (HQL) instruments in studies of patients with rheumatoid arthritis (RA)., Methods: Patients with RA (n = 693) who were enrolled in 2 double-blind, placebo-controlled clinical trials completed the Short Form 36 (SF-36) modified health survey and the Health Assessment Questionnaire (HAQ) disability index at baseline and 6-week followup assessments. Data on 5 RA severity measures were also collected at baseline and at 6 weeks (patient and physician global assessments, joint swelling and tenderness counts, and global pain assessment). Comparison of changes in the SF-36 scales and HAQ scores was made between groups of patients known to differ in the level of change on each RA severity measure., Results: With few exceptions, changes in the SF-36 and HAQ scores were different between patients who differed in the level of change on each RA severity measure. Changes in the SF-36 and HAQ scores were more strongly related to changes in the patient and physician global assessments and patient pain assessment than to changes in the joint swelling and tenderness counts., Conclusion: Based on these results, minimally important changes in the SF-36 scales and HAQ disability scores were determined, which will be useful in interpreting HQL results in clinical trials.

We studied 31 previously validated and newly developed generic and epilepsy-specific scales to evaluate their usefulness for assessing the impact of epilepsy and anti-epileptic drug (AED) therapy on health-related quality of life (HRQOL). Included were the MOS SF-36 Health Survey, additional measures of mental health, cognition, epilepsy-specific perception of control, behavioural problems, distress, worries and experiences, the Liverpool Epilepsy Impact and Seizure Severity scales, and a patient-completed symptom checklist. Questionnaires were completed twice by 136 patients on AED therapy in a multicentre study in the UK. Validity was assessed in relation to disease severity, defined as time since last seizure, and to patient-reported symptoms. Statistical analyses to estimate the contribution of HRQOL information of each scale relative to that of others were conducted. The 171-item questionnaire could be completed by out-patients with epilepsy with good data quality. With few exceptions, generic and epilepsy-specific measures satisfied psychometric tests of hypothesized item groupings and scale score reliability (internal consistency and test-retest reliability) and differentiated well between groups of patients differing in time since last seizure and in symptom impact, regardless of time since last seizure. However, scales differed widely in their validity in discriminating between groups of patients known to differ clinically. The SF-36 Role Physical scale best discriminated among groups differing in disease severity. The epilepsy-specific Mastery, Impact, Experience, Worry, Distress, and Agitation scales were among the 10 best measures in discriminating among groups differing in disease severity. Generic measures, especially measures of social and role functioning and mental health, were best at differentiating groups of patients differing in symptom impact. Recommendations are offered for concepts and specific scales most likely to be useful in future studies of the HRQOL burden of epilepsy and the HRQOL benefits of AED therapy.