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Objective: Patient-reported transition ratings are supposed to reflect the change between a previous baseline health state and a present follow-up state, but may reflect the present state to a greater extent. This so-called “present state bias” (PSB) potentially threatens the validity of transition ratings. Several criteria have been proposed to assess PSB. We examined how well these criteria perform and to which extent confirmatory factor analysis (CFA) for categorical data provides an accurate assessment of the degree of PSB. Study Design and Setting: We simulated multiple samples with baseline and follow-up item responses to a hypothetical questionnaire, and transition ratings. The samples varied with respect to various distributional characteristics and the degree of PSB. The performance of criteria proposed in the literature, and a new CFA-based criterion, were evaluated by the proportion of explained variance in PSB. In addition, four real datasets were analyzed. Results: The known criteria explained 36–74% of the variance in PSB. A new CFA-based criterion, namely the ratio of the factor loadings of the transition ratings plus one, explained 81–98% of the variance in PSB across the samples. Conclusion: Present state bias in transition ratings can be estimated accurately using CFA.

Background There are increasing concerns about the appropriateness of generic preference-based measures to capture health benefits in the area of mental health. Objectives The aim of this study is to estimate preference weights for a new measure, Recovering Quality of Life (ReQoL-10), to better capture the benefits of mental healthcare. Methods Psychometric analyses of a larger sample of mental health service users (n = 4266) using confirmatory factor analyses and item response theory were used to derive a health state classification system and inform the selection of health states for utility assessment. A valuation survey with members of the UK public representative in terms of age, sex, and region was conducted using face-to-face interviewer administered time-trade-off with props. A series of regression models were fitted to the data and the best performing model selected for the scoring algorithm. Results The ReQoL-Utility Index (UI) classification system comprises 6 mental health items and 1 physical health item. Sixty-four health states were valued by 305 participants. The preferred model was a random effects model, with significant and consistent coefficients and best model fit. Estimated utilities modeled for all health states ranged from −0.195 (state worse than dead) to 1 (best possible state). Conclusions The development of the ReQoL-UI is based on a novel application of item response theory methods for generating the classification system and selecting health states for valuation. Conventional time-trade-off was used to elicit utility values that are modeled to enable the generation of QALYs for use in cost-utility analysis of mental health interventions., Highlights • In light of concerns around the use of EQ-5D to assess mental health outcomes, there is a need for a new generic preference-based measure with focus on mental health for use in the economic evaluation of interventions aimed at improving outcomes in this area. • This paper uses item response theory (IRT) to construct a health classification system for the ReQoL-10 and the ReQoL-20. IRT was also used in a novel way to select health states amenable for valuation, ensuring the plausibility of these states. Preference weights were generated to enable utilities to be calculated from ReQoL-10 and ReQoL-20. • The paper highlights a novel method of selecting health states for valuation purposes. An algorithm is presented to generate quality adjusted life years from the ReQoL measures for use in the economic evaluation of health and care interventions in the area of mental health. Future research comparing ReQoL-UI and EQ-5D will determine whether the former presents an improvement in capturing benefits in the area of mental health.

Objectives Clinical practice guidelines recommend questionnaires with short recall. We compare responsiveness of ecological momentary assessments (EMAs) and retrospective assessments of thyroid-related quality of life. Study Design and Setting Patients with newly diagnosed thyrotoxicosis completed retrospective Thyroid-related Patient-Reported Outcome measures (ThyPROs) with 4-week and 1-week recall, respectively, and three daily EMAs for 4 weeks at time of inclusion and again after treatment (N = 115). Magnitude of change and statistical power (F-test statistics) were compared. Two designs were applied to the same data: Design 1 mimicked the practical realities of clinical trials by comparing 4-week recall ThyPRO administered at time of inclusion with EMA initiated at time of inclusion and collected prospectively for 1 week, thus not covering the same time frame or duration. Design 2 compared assessments covering the same 4 weeks after inclusion. Results Design 1: the estimated change and statistical power were significantly larger for 4-week ThyPRO compared with EMAs. Design 2: retrospective assessments and EMAs had comparable change and power. Repeated 1-week ThyPRO administrations increased the statistical power. Conclusion Selecting the optimal time frame for evaluation proved crucial for responsiveness. EMAs did not provide higher responsiveness than retrospective measures in either design. Repeated 1-week ThyPRO administrations increased statistical power.

Background: Workplace bullying may severely affect mental health, but its association with suicidal behaviour is unknown. We analysed whether individuals reporting exposure to workplace bullying had higher risk of suicidal behaviour than those not reporting such exposure. Methods: Using a prospective cohort study design, we linked data from nine Danish questionnaire-based surveys (2004-2014) to national register data until December 31st, 2016. Exposure to workplace bullying was measured by a single item. Suicide attempts were identified in hospital registers and death by suicide in the Cause of Death Register. Among participants with no previous suicide attempts, we estimated Hazard Ratios (HR) and 95% Confidence Intervals (CI), adjusting for sex, age, marital status, socio-economic status, and history of psychiatric morbidity. Outcomes: The sample consisted of 98 330 participants (713 809 person-years); 63·6% women, mean age 44·5 years. Workplace bullying was reported by 10 259 participants (10·4%). During a mean follow-up of 7·3 years, we observed 186 cases of suicidal behaviour, including 145 suicide attempts, 36 deaths by suicide and 5 cases that died by suicide after surviving a suicide attempt. The fully-adjusted HR for the association between workplace bullying and suicidal behaviour was 1·70 (95% CI 1·10–2·61). The HRs for suicide attempts and death by suicide were 1·72 (1·14–2·58) and 2·29 (1·00–5·53), respectively. A multiplicative interaction with sex (2·78, CI 1·59–4·88) indicated that workplace bullying was associated with suicidal behaviour among men. Interpretation: The results suggested an elevated risk of suicidal behaviour among men reporting workplace bullying. Funding Information: Region of Southern Denmark (grant number A1763); Danish Working Environment Research Fund (grant number 20130023294); Danish Working Environment Research Fund (grant number 10-2019-03). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: The project has been approved by the Danish Data Protection Agency (Capital Region of Denmark; j.nr.: 2012-58-0004).

Objective Generic preference-based measures such as the EuroQol five-dimensional questionnaire (EQ-5D) are used in economic evaluation, but may not be appropriate for all conditions. When this happens, a possible solution is adding bolt-ons to expand their descriptive systems. Using review-based methods, studies published to date claimed the relevance of bolt-ons in the presence of poor psychometric results. This approach does not identify the specific dimensions missing from the Generic preference-based measure core descriptive system, and is inappropriate for identifying dimensions that might improve the measure generically. This study explores the use of principal-component analysis (PCA) and confirmatory factor analysis (CFA) for bolt-on identification in the EQ-5D. Methods Data were drawn from the international Multi-Instrument Comparison study, which is an online survey on health and well-being measures in five countries. Analysis was based on a pool of 92 items from nine instruments. Initial content analysis provided a theoretical framework for PCA results interpretation and CFA model development. PCA was used to investigate the underlining dimensional structure and whether EQ-5D items were represented in the identified constructs. CFA was used to confirm the structure. CFA was cross-validated in random halves of the sample. Results PCA suggested a nine-component solution, which was confirmed by CFA. This included psychological symptoms, physical functioning, and pain, which were covered by the EQ-5D, and satisfaction, speech/cognition,relationships, hearing, vision, and energy/sleep which were not. These latter factors may represent relevant candidate bolt-ons. Conclusions PCA and CFA appear useful methods for identifying potential bolt-ons dimensions for an instrument such as the EQ-5D.

Summary Background Working long hours might have adverse health effects, but whether this is true for all socioeconomic status groups is unclear. In this meta-analysis stratified by socioeconomic status, we investigated the role of long working hours as a risk factor for type 2 diabetes. Methods We identified four published studies through a systematic literature search of PubMed and Embase up to April 30, 2014. Study inclusion criteria were English-language publication; prospective design (cohort study); investigation of the effect of working hours or overtime work; incident diabetes as an outcome; and relative risks, odds ratios, or hazard ratios (HRs) with 95% CIs, or sufficient information to calculate these estimates. Additionally, we used unpublished individual-level data from 19 cohort studies from the Individual-Participant-Data Meta-analysis in Working-Populations Consortium and international open-access data archives. Effect estimates from published and unpublished data from 222 120 men and women from the USA, Europe, Japan, and Australia were pooled with random-effects meta-analysis. Findings During 1·7 million person-years at risk, 4963 individuals developed diabetes (incidence 29 per 10 000 person-years). The minimally adjusted summary risk ratio for long (≥55 h per week) compared with standard working hours (35–40 h) was 1·07 (95% CI 0·89–1·27, difference in incidence three cases per 10 000 person-years) with significant heterogeneity in study-specific estimates ( I 2 =53%, p=0·0016). In an analysis stratified by socioeconomic status, the association between long working hours and diabetes was evident in the low socioeconomic status group (risk ratio 1·29, 95% CI 1·06–1·57, difference in incidence 13 per 10 000 person-years, I 2 =0%, p=0·4662), but was null in the high socioeconomic status group (1·00, 95% CI 0·80–1·25, incidence difference zero per 10 000 person-years, I 2 =15%, p=0·2464). The association in the low socioeconomic status group was robust to adjustment for age, sex, obesity, and physical activity, and remained after exclusion of shift workers. Interpretation In this meta-analysis, the link between longer working hours and type 2 diabetes was apparent only in individuals in the low socioeconomic status groups. Funding Medical Research Council, European Union New and Emerging Risks in Occupational Safety and Health research programme, Finnish Work Environment Fund, Swedish Research Council for Working Life and Social Research, German Social Accident Insurance, Danish National Research Centre for the Working Environment, Academy of Finland, Ministry of Social Affairs and Employment (Netherlands), Economic and Social Research Council, US National Institutes of Health, and British Heart Foundation.

Objectives To test the impact of the method of administration (MOA) on score level, reliability, and validity of scales developed in the Patient Reported Outcomes Measurement Information System (PROMIS). Study Design and Setting Two nonoverlapping parallel forms each containing eight items from each of three PROMIS item banks (Physical Function, Fatigue, and Depression) were completed by 923 adults with chronic obstructive pulmonary disease, depression, or rheumatoid arthritis. In a randomized crossover design, subjects answered one form by interactive voice response (IVR) technology, paper questionnaire (PQ), personal digital assistant (PDA), or personal computer (PC) and a second form by PC, in the same administration. Method equivalence was evaluated through analyses of difference scores, intraclass correlations (ICCs), and convergent/discriminant validity. Results In difference score analyses, no significant mode differences were found and all confidence intervals were within the prespecified minimal important difference of 0.2 standard deviation. Parallel-forms reliabilities were very high (ICC = 0.85–0.93). Only one across-mode ICC was significantly lower than the same-mode ICC. Tests of validity showed no differential effect by MOA. Participants preferred screen interface over PQ and IVR. Conclusion We found no statistically or clinically significant differences in score levels or psychometric properties of IVR, PQ, or PDA administration compared with PC.

Background Published work assessing psychosocial stress (job strain) as a risk factor for coronary heart disease is inconsistent and subject to publication bias and reverse causation bias. We analysed the relation between job strain and coronary heart disease with a meta-analysis of published and unpublished studies. Methods We used individual records from 13 European cohort studies (1985-2006) of men and women without coronary heart disease who were employed at time of baseline assessment. We measured job strain with questions from validated job-content and demand-control questionnaires. We extracted data in two stages such that acquisition and harmonisation of job strain measure and covariables occurred before linkage to records for coronary heart disease. We defined incident coronary heart disease as the first non-fatal myocardial infarction or coronary death. Findings 30 214 (15%) of 197 473 participants reported job strain. In 1•49 million person-years at risk (mean follow-up 7•5 years [SD 1•7]), we recorded 2358 events of incident coronary heart disease. After adjustment for sex and age, the hazard ratio for job strain versus no job strain was 1•23 (95% CI 1•10-1•37). This effect estimate was higher in published (1•43, 1•15-1•77) than unpublished (1•16, 1•02-1•32) studies. Hazard ratios were likewise raised in analyses addressing reverse causality by exclusion of events of coronary heart disease that occurred in the first 3 years (1•31, 1•15-1•48) and 5 years (1•30, 1•13-1•50) of follow-up. We noted an association between job strain and coronary heart disease for sex, age groups, socioeconomic strata, and region, and after adjustments for socioeconomic status, and lifestyle and conventional risk factors. The population attributable risk for job strain was 3•4%. Interpretation Our findings suggest that prevention of workplace stress might decrease disease incidence; however, this strategy would have a much smaller effect than would tackling of standard risk factors, such as smoking. Funding Finnish Work Environment Fund, the Academy of Finland, the Swedish Research Council for Working Life and Social Research, the German Social Accident Insurance, the Danish National Research Centre for the Working Environment, the BUPA Foundation, the Ministry of Social Affairs and Employment, the Medical Research Council, the Wellcome Trust, and the US National Institutes of Health. CODEN: LANCA

The aim of this article is to report the development and preliminary testing of a prototype computerized adaptive test of chronic pain (CHRONIC PAIN-CAT) conducted in 2 stages: (1) evaluation of various item selection and stopping rules through real data-simulated administrations of CHRONIC PAIN-CAT; (2) a feasibility study of the actual prototype CHRONIC PAIN-CAT assessment system conducted in a pilot sample. Item calibrations developed from a US general population sample (N = 782) were used to program a pain severity and impact item bank (kappa = 45), and real data simulations were conducted to determine a CAT stopping rule. The CHRONIC PAIN-CAT was programmed on a tablet PC using QualityMetric's Dynamic Health Assessment (DYHNA) software and administered to a clinical sample of pain sufferers (n = 100). The CAT was completed in significantly less time than the static (full item bank) assessment (P.001). On average, 5.6 items were dynamically administered by CAT to achieve a precise score. Scores estimated from the 2 assessments were highly correlated (r = .89), and both assessments discriminated across pain severity levels (P.001, RV = .95). Patients' evaluations of the CHRONIC PAIN-CAT were favorable.This report demonstrates that the CHRONIC PAIN-CAT is feasible for administration in a clinic. The application has the potential to improve pain assessment and help clinicians manage chronic pain.

Objective: The Patient-Reported Outcomes Measurement Information System (PROMIS) was initiated to improve precision, reduce respondent burden, and enhance the comparability of health outcomes measures. We used item response theory (IRT) to construct and evaluate a preliminary item bank for physical function assuming four subdomains. Study Design and Setting: Data from seven samples (N 517,726) using 136 items from nine questionnaires were evaluated. A generalized partial credit model was used to estimate item parameters, which were normed to a mean of 50 (SD 510) in the US population. Item bank properties were evaluated through Computerized Adaptive Test (CAT) simulations. Results: IRT requirements were fulfilled by 70 items covering activities of daily living, lower extremity, and central body functions. The original item context partly affected parameter stability. Items on upper body function, and need for aid or devices did not fit the IRT model. In simulations, a 10-item CAT eliminated floor and decreased ceiling effects, achieving a small standard error (!2.2) across scores from 20 to 50 (reliability O0.95 for a representative US sample). This precision was not achieved over a similar range by any comparable fixed length item sets. Conclusion: The methods of the PROMIS project are likely to substantially improve measures of physical function and to increase the

Breast cancer and its treatment have been associated with psychological morbidity. In this study our aim was to quantify the excess anxiety and depression resulting from breast cancer. We compared 538 newly diagnosed breast cancer patients at low risk of recurrence (87.0% responded) to 872 women randomly selected from the Danish general population (69.7% responded) using the Hospital Anxiety and Depression Scale (HADS). Contrary to expectations, the proportions classified as “cases” of anxiety and depression were not significantly different in the two groups. The breast cancer patients’ mean HADS scores were significantly lower than those in the general population sample (anxiety, P = 0.021; depression, P

Rasch models for polytomous items were used to assess the scaling assumptions and compare item response patterns in the 10-item SF-36 physical functioning scale (PF-10) for general population respondents in Denmark, Germany, Italy, the Netherlands, Sweden, the United Kingdom, and the United States. The Rasch model of physical functioning developed in the United States was compared to models for other countries, and each country was compared to a multinational composite. Strong scale congruence across the seven countries was demonstrated; items that varied between countries and from the composite may reflect unique cultural response patterns or differences in translation. Scoring algorithms based on the Rasch model for each country were superior to the current Likert scoring in tests of relative validity (RV) in discriminating among age groups in all countries. In relation to the Likert PF-10 scoring (RV = 1.00), scores estimated using the Rasch rating scale model achieve a median RV of 1.31 (range: 1.01-1.59), while the Rasch partial credit model attained a median RV of 1.44 (range: 1.01-2.23). Rasch models hold good potential for improving health status measures, estimating individual scores when responses to scale items are missing, and equating scores across countries.

Data from general population samples in 11 countries (n = 1483 to 9151) were used to assess data quality and test the assumptions underlying the construction and scoring of multi-item scales from the SF-36 Health Survey. Across all countries, the rate of item-level missing data generally was low, although slightly higher for items printed in the grid format. In each country, item means generally were clustered as hypothesized within scales. Correlations between items and hypothesized scales were greater than 0.40 with one exception, supporting item internal consistency. Items generally correlated significantly higher with their own scale than with competing scales, supporting item discriminant validity. Scales could be constructed for 93-100% of respondents. Internal consistency reliability of the eight SF-36 scales was above 0.70 for all scales, with two exceptions. Floor effects were low for all except the two role functioning scales; ceiling effects were high for both role functioning scales and also were noteworthy for the Physical Functioning, Bodily Pain, and Social Functioning scales in some countries. These results support the construction and scoring of the SF-36 translations in these 11 countries using the method of summated ratings.

Increasingly, translated and culturally adapted health-related quality of life measures are being used in cross-cultural research. To assess comparability of results, researchers need to know the comparability of the content of the questionnaires used in different countries. Based on an item-by-item discussion among International Quality of Life Assessment (IQOLA) investigators of the content of the translated versions of the SF-36 in 10 countries, we discuss the difficulties that arose in translating the SF-36. We also review the solutions identified by IQOLA investigators to translate items and response choices so that they are appropriate within each country as well as comparable across countries. We relate problems and solutions to ratings of difficulty and conceptual equivalence for each item. The most difficult items to translate were physical functioning items that refer to activities not common outside the United States and items that use colloquial expressions in the source version. Identifying the origin of the source items, their meaning to American English-speaking respondents and American English synonyms, in response to country-specific translation issues, greatly helped the translation process. This comparison of the content of translated SF-36 items suggests that the translations are culturally appropriate and comparable in their content.

A crucial prerequisite to the use of the SF-36 Health Survey in multinational studies is the reproduction of the conceptual model underlying its scoring and interpretation. Structural equation modeling (SEM) was used to test these aspects of the construct validity of the SF-36 in ten IQOLA countries: Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, the United Kingdom, and the United States. Data came from general population surveys fielded to gather normative data. Measurement and structural models developed in the United States were cross-validated in random halves of the sample in each country. SEM analyses supported the eight first-order factor model of health that underlies the scoring of SF-36 scales and two second-order factors that are the basis for summary physical and mental health measures. A single third-order factor was also observed in support of the hypothesis that all responses to the SF-36 are generated by a single, underlying construct--health. In addition, a third second-order factors, interpreted as general well-being, was shown to improve the fit of the model. This model (including eight first-order factors, three second-order factors, and one third-order factor) was cross-validated using a holdout sample within the United States and in each of the nine other countries. These results confirm the hypothesized relationships between SF-36 items and scales and justify their scoring in each country using standard algorithms. Results also suggest that SF-36 scales and summary physical and mental health measures will have similar interpretations across countries. The practical implications of a third second-order SF-36 factor (general well-being) warrant further study.

The similarity in meaning assigned to response choice labels from the SF-36 Health Survey (SF-36) was evaluated across countries. Convenience samples of judges (range, 10 to 117; median = 48) from 13 countries rated translations of response choice labels, using a variation of the Thurstone method of equal appearing intervals. Judges marked a point on a 10-cm line-representing the magnitude of a response choice label (e.g., "good" relative to the anchors of "poor" and "excellent"). Ratings were evaluated to determine the ordinal consistency of response choice labels within a response scale; the degree to which differences between adjacent response choice labels were equal interval; and the amount of variance due to response choice label, country, judge, and interaction between response choice label and country. Results confirmed the hypothesized ordering of response choice labels; the percentage of ordinal pairs ranged from 88.7% to 100% (median = 98.2%) across countries and response scales. Examination of the average magnitudes of response choice labels supported the "quasi-interval" nature of the scales. Analysis of variance (ANOVA) results supported the generalizability of response choice magnitudes across countries; labels explained 64% to 77% of the variance in ratings, and country explained 1% to 3%. These results support the equivalence of SF-36 response choice labels across countries. Departures from the assumption of equal intervals, when observed, were similar across countries and were greatest for the two response scales that are recalibrated under standard SF-36 scoring. Results provide justification for scoring translations of individual items using standard SF-36 scoring; whether these items form the same scales in other countries as they do in the United States is evaluated with tests of scaling assumptions.

This article reports on the Danish translation of SF-36 and discusses the procedures used for translation improvement, translation evaluation, and scale evaluation. We followed the standard procedures of the International Quality of Life Assessment (IQOLA) Project including forward and backward translation, independent assessment of translation quality, assessment of response-choice weighting through visual analogue scale (VAS) investigations, and psychometric testing of the translated questionnaire. We found that backward translation, independent quality assessment, and VAS studies provided useful information for translation improvement. The Danish SF-36 received a favorable translation evaluation by independent rating; however, interrater agreement was low. Preliminary validity studies generally supported the internal consistency and homogeneity of the Danish SF-36, and the questionnaire performed satisfactorily in distinguishing depressive patients from nonpatients. On the basis of this and other studies, we recommend use of the Danish SF-36 in research.

Data from general population surveys (n = 1483 to 9151) in nine European countries (Denmark, France, Germany, Italy, the Netherlands, Norway, Spain, Sweden, and the United Kingdom) were analyzed to cross-validate the selection of questionnaire items for the SF-12 Health Survey and scoring algorithms for 12-item physical and mental component summary measures. In each country, multiple regression methods were used to select 12 SF-36 items that best reproduced the physical and mental health summary scores for the SF-36 Health Survey. Summary scores then were estimated with 12 items in three ways: using standard (U.S.-derived) SF-12 items and scoring algorithms; standard items and country-specific scoring; and country-specific sets of 12 items and scoring. Replication of the 36-item summary measures by the 12-item summary measures was then evaluated through comparison of mean scores and the strength of product-moment correlations. Product-moment correlations between SF-36 summary measures and SF-12 summary measures (standard and country-specific) were very high, ranging from 0.94-0.96 and 0.94-0.97 for the physical and mental summary measures, respectively. Mean 36-item summary measures and comparable 12-item summary measures were within 0.0 to 1.5 points (median = 0.5 points) in each country and were comparable across age groups. Because of the high degree of correspondence between summary physical and mental health measures estimated using the SF-12 and SF-36, it appears that the SF-12 will prove to be a practical alternative to the SF-36 in these countries, for purposes of large group comparisons in which the focus is on overall physical and mental health outcomes.

Statistical analyses of Differential Item Functioning (DIF) can be used for rigorous translation evaluations. DIF techniques test whether each item functions in the same way, irrespective of the country, language, or culture of the respondents. For a given level of health, the score on any item should be independent of nationality. This requirement can be tested through contingency-table methods, which are efficient for analyzing all types of items. We investigated DIF in the Danish translation of the SF-36 Health Survey, using two general population samples (USA, n = 1,506; Denmark, n = 3,950). DIF was identified for 12 out of 35 items. These results agreed with independent ratings of translation quality, but the statistical techniques were more sensitive. When included in scales, the items exhibiting DIF had only a little impact on conclusions about cross-national differences in health in the general population. However, if used as single items, the DIF items could seriously bias results from cross-national comparisons. Also, the DIF items might have larger impact on cross-national comparison of groups with poorer health status. We conclude that analysis of DIF is useful for evaluating questionnaire translations.

Item bias (differential item functioning) analysis examines whether the construction of an index from two or more variables results in bias in relation to sex, age, or other criteria. Item bias may lead to erroneous conclusions because of distortion or dilution of the effects measured. In comparing groups, item bias analysis, tests whether the information about possible differences between groups, obtained by the variables constituting an index, are correctly passed on by the index score. We examined a quality of life questionnaire answered by 1189 breast cancer patients. We found age-bias or bias in the comparison of groups receiving different treatments in three out of nine indexes. Recommendations for the interpretation of these indexes are made. Item bias analysis is a useful method examining an issue not covered by traditional psychometric tests.

Objectives This study aimed to develop and evaluate a first computerized adaptive test (CAT) for the measurement of stress perception (Stress-CAT), in terms of the two dimensions: exposure to stress and stress reaction . Study Design and Setting Item response theory modeling was performed using a two-parameter model (Generalized Partial Credit Model). The evaluation of the Stress-CAT comprised a simulation study and real clinical application. A total of 1,092 psychosomatic patients (N1) were studied. Two hundred simulees (N2) were generated for a simulated response data set. Then the Stress-CAT was given to n =116 inpatients, (N3) together with established stress questionnaires as validity criteria. Results The final banks included n =38 stress exposure items and n =31 stress reaction items. In the first simulation study, CAT scores could be estimated with a high measurement precision (SE 0.90) using 7.0±2.3 (M±SD) stress reaction items and 11.6±1.7 stress exposure items. The second simulation study reanalyzed real patients data (N1) and showed an average use of items of 5.6±2.1 for the dimension stress reaction and 10.0±4.9 for the dimension stress exposure . Convergent validity showed significantly high correlations. Conclusions The Stress-CAT is short and precise, potentially lowering the response burden of patients in clinical decision making.

PAR10 IMPROVING THE SENSITIVITY OF PHYSICAL FUNCTION MEASURES IN RHEUMATOID ARTHRITIS: USE OF ITEM RESPONSE THEORY IN PATIENTS TREATED WITH ABATACEPT (CTLA4IG) Martin M, Emery P, Kosinski M,Ware J, Li T,Williams R, Maclean R, Bjorner J Quality Metric, Inc, Lincoln, RI, USA; University of Leeds, Leeds, United Kingdom; Bristol-Myers Squibb, Princeton, NJ, USA; Bristol-Myers Squibb, Brussels, Belgium OBJECTIVES: The Health Assessment Questionnaire (HAQ) and the Modified HAQ (MHAQ) are examples of common short-forms of physical function used to measure improvement in the treatment of rheumatoid arthritis (RA) which have been associated with ceiling problems. These problems, inherent to short-form surveys, pose risks of failing to detect a treatment response in clinical trials. Item Response Theory (IRT) methods were used to examine the properties of two physical function measures and construct a combined measure to better detect changes in disease activity and treatment response. METHODS: Data were from a 12-month, double-blind, multi-center study of 339 RA patients on a background of methotrexate randomized to Abatacept at 2mg/kg, at 10mg/kg, or placebo. MHAQ and SF-36 (with its Physical Functioning scale, PF10) were administered at pretreatment and 3, 6, and 12 months post-treatment. IRT methods were used to examine the surveys’ measurement properties and compute new IRT-based physical function scores. Analyses of variance were used to assess sensitivity to changes in disease severity and treatment response. Relative validity coefficients were used to compare the measures. RESULTS: A Rasch IRT model fit the data. IRT-based scores successfully lowered the floor and raised the ceiling of the physical function measured. IRT-based scores were 30% more efficient than MHAQ and 50% more efficient than PF10 in discriminating among ACR groups. In discriminating among treatment groups, IRT-based scores were 25% more efficient than MHAQ and 12% more efficient than PF10 at 6-months; and 16% and 17% more efficient at 12-months based on observed effect sizes. CONCLUSIONS: Using IRT methodology to estimate a combined score for physical functioning lead to greater range of the construct measured. The improved measure, with greater measurement precision and sensitivity to treatment response, further confirmed the beneficial effect of Abatacept on physical function in the treatment of RA.

OBJECTIVES: The aim of this study was to test the unidimensionality of 65 items from nine widely used pain questionnaires in preparation for computerized adaptive pain assessment. METHODS: Random samples of adults were contacted on the internet (N = 782) and telephone (N = 750). 65 items were selected mainly from Brief Pain Inventory, MOS Pain Measures, Oswestry Low Back Pain Disability Questionnaire, NottingHam Health Profile, McGill Pain Questionnaire, Health Disability Index, Migraine-Specific Questionnaire, Aberdeen Back Pain Scale, and Headache Impact Test. Mplus software was used to perform confirmatory and exploratory factor analyses of polychoric correlations among the items. Model was examined through eigenvalue analysis, interfactor correlations, and root mean square residuals. RESULTS: Confirmatory factor loadings ranged from 0.53 to 0.92 with 90% of them higher than 0.7. Three factors were rotated to an oblique solution. Examination of exploratory factor analysis revealed two subdimensions of pain based upon item content: pain severity and pain impact. The third dimension observed in the three-factor solution, interpreted as current pain, was defined by questions without recall period. Eigenvalue analyses showed that the first factor explained more than 65 percent of the total variance in all pain item scores. Three factors explained 74% of the variance. The interfactor correlations were high, ranged from 0.64 to 0.67. Root mean square residuals were low, 0.07 for one-factor solution and 0.05, 0.03 for two- and three-factor solution respectively. CONCLUSION: Most items from widely used questionnaires measure one single underlying construct of pain sufficiently to meet the assumption of Item Response Theory. Items selected will be calibrated on a standard metric to estimate scores at patient's specific pain level. Further investigation on the application of IRT methods and computer technology in pain assessment is warranted.