Extending the PROMIS item bank "ability to participate in social roles and activities": a psychometric evaluation using IRT.

OBJECTIVE: Our objective was to explore whether the extension of the PROMIS item bank Ability to Participate in Social Roles and Activities (APSRA) with new items would result in more effective targeting (i.e., selecting items that are appropriate for each individual's trait level), and more reliable measurements across all latent trait levels. METHODS: A sample of 1,022 Dutch adults completed all 35 items of the original item bank plus 17 new items (in Dutch). The new items presented in this publication have been translated provisionally from Dutch into English for presentation purposes. We evaluated the basic IRT assumptions unidimensionality, local independence, and monotonicity. Furthermore, we examined the item parameters, and assessed differential item functioning (DIF) for sex, education, region, age, and ethnicity. In addition, we compared the test information functions, item parameters, and θ scores, for the original and extended item bank in order to assess whether the measurement range had improved. RESULTS: We found that the extended item bank was compatible with the basic IRT assumptions and showed good reliability. Moreover, the extended item bank improved the measurement in the lower trait range, which is important for reliably assessing functioning in clinical populations (i.e., persons reporting lower levels of participation). CONCLUSION: We extended the PROMIS-APSRA item bank and improved its psychometric quality. Our study contributes to PROMIS measurement innovation, which allows for the addition of new items to existing item banks, without changing the interpretation of the scores and while maintaining the comparability of the scores with other PROMIS instruments.

Evaluating the Construct Validity of the Norwegian Version of the Level of Personality Functioning Scale - Brief Form 2.0 in a Large Clinical Sample.

The Level of Personality Functioning - Brief Form 2.0 (LPFS-BF 2.0) is a 12-item self-report questionnaire developed to gain a quick impression of the severity of personality pathology according to the DSM-5 Alternative Model for Personality Disorders (AMPD). The current study evaluated the construct validity and reliability of the Norwegian version of the LPFS-BF 2.0 in a large clinical sample (N = 1673). Dimensionality was examined using confirmatory factor analysis and bifactor analysis followed by an analysis of distinctiveness of the subscales using the proportional reduction in mean squared error (PRMSE), and the concurrent validity was examined using correlations with self-report questionnaires and clinical interviews assessing PDs according to section II of the DSM-5. Taking the findings of the dimensionality and concurrent validity results together, we found moderate to good support for the use of total scores for the Norwegian version of the LPFS-BF 2.0. We would advise against the use of subscale scores, since the subscales provided only a small amount of reliable unique variance.

Do Flexible Administration Procedures Promote Individualized Clinical Assessments? An Explorative Analysis of How Clinicians Utilize the Funnel Structure of the SCID-5-AMPD Module I: LPFS.

The current study examined clinicians' utilization of the SCID-5-AMPD-I funnel structure. Across 237 interviews, conducted as part of the NorAMP study, we found that clinicians administered on average 2-3 adjacent levels under each subdomain, effectively administering only about 50% of available items. Comparing administration patterns of interviews, no two interviews contained the exact same set of administered items. On average, when comparing individual interviews, only about half of the administered items in each interview were administered in both interviews. Cross-classified mixed effects models were estimated to examine the factors affecting item administration. Results indicated that the interplay between patient preliminary scores and item level had a substantial impact on item administration, suggesting clinicians tend to administer items corresponding to expected patient severity. Overall, our findings suggest clinicians utilize the SCID-5-AMPD-I funnel structure to conduct efficient and individually tailored assessments informed by relevant patient characteristics. Adopting similar non-fixed administration procedures for other interviews could potentially provide similar benefits compared to traditional fixed-form administration procedures. The current study can serve as a template for verifying and evaluating future adoptions of non-fixed administration procedures in other interviews.

The Incremental Utility of Criteria A and B of the DSM-5 Alternative Model for Personality Disorders for Predicting DSM-IV/DSM-5 Section II Personality Disorders.

The DSM-5 Alternative Model for Personality Disorders (AMPD) includes two main criteria: moderate or greater impairment in personality functioning (Criterion A) and the presence of one or more pathological personality traits (Criterion B). The aim of the study was to investigate the incremental utility of Criteria A and B for predicting DSM-5 Section II personality disorders (PD). The sample (N = 317) consisted of three well-defined groups: non-clinical participants (n = 35), psychiatric patients with PD (n = 193), and without PD (n = 83). All were assessed using the Structured Clinical Interview for the DSM-5 Alternative Model for Personality Disorders Module I (SCID-5-AMPD-I): Level of Personality Functioning Scale (LPFS), and the Personality Inventory for DSM-5 (PID-5). Logistic regression analyses showed that the SCID-5-AMPD-I could predict the presence of PDs in general, and the three specific PDs that were investigated (i.e., Antisocial, Borderline, and Avoidant PDs). The PID-5 domains enhanced prediction of the specific PDs, but not the presence of PDs in general, when entered in the second step. Our results support the AMPD model: Criterion A predicted the presence of DSM-5 Section II PDs in general, whereas measures of Criterion B incremented prediction of Antisocial, Borderline, and Avoidant PDs.

A systematic review of measurement uncertainty visualizations in the context of standardized assessments.

This systematic review summarized findings of 29 studies evaluating visual presentation formats appropriate for communicating measurement uncertainty associated with standardized clinical assessment instruments. Studies were identified through systematic searches of multiple databases (Medline, Embase, PsycInfo, ERIC, Scopus, and Web of Science). Strikingly, we found no studies which were conducted using samples of clinicians and included clinical decision-making scenarios. Included studies did however find that providing participants with information about measurement uncertainty may increase awareness of uncertainty and promote more optimal decision making. Formats which visualize the shape of the underlying probability distribution were found to promote more accurate probability estimation and appropriate interpretations of the underlying probability distribution shape. However, participants in the included studies did not seem to benefit from the additional information provided by such plots during decision-making tasks. Further explorations into how presentations of measurement uncertainty impact clinical decision making are needed to examine whether findings of the included studies generalize to clinician populations. This review provides an important overview of pitfalls associated with formats commonly used to communicate measurement uncertainty in clinical assessment instruments, and a potential starting point for further explorations into promising alternatives. Finally, our review offers specific recommendations on how remaining research questions might be addressed.

Symptom burden and health-related quality of life in chronic kidney disease: A global systematic review and meta-analysis.

BACKGROUND: The importance of patient-reported outcome measurement in chronic kidney disease (CKD) populations has been established. However, there remains a lack of research that has synthesised data around CKD-specific symptom and health-related quality of life (HRQOL) burden globally, to inform focused measurement of the most relevant patient-important information in a way that minimises patient burden. The aim of this review was to synthesise symptom prevalence/severity and HRQOL data across the following CKD clinical groups globally: (1) stage 1-5 and not on renal replacement therapy (RRT), (2) receiving dialysis, or (3) in receipt of a kidney transplant. METHODS AND FINDINGS: MEDLINE, PsycINFO, and CINAHL were searched for English-language cross-sectional/longitudinal studies reporting prevalence and/or severity of symptoms and/or HRQOL in CKD, published between January 2000 and September 2021, including adult patients with CKD, and measuring symptom prevalence/severity and/or HRQOL using a patient-reported outcome measure (PROM). Random effects meta-analyses were used to pool data, stratified by CKD group: not on RRT, receiving dialysis, or in receipt of a kidney transplant. Methodological quality of included studies was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Studies Reporting Prevalence Data, and an exploration of publication bias performed. The search identified 1,529 studies, of which 449, with 199,147 participants from 62 countries, were included in the analysis. Studies used 67 different symptom and HRQOL outcome measures, which provided data on 68 reported symptoms. Random effects meta-analyses highlighted the considerable symptom and HRQOL burden associated with CKD, with fatigue particularly prevalent, both in patients not on RRT (14 studies, 4,139 participants: 70%, 95% CI 60%-79%) and those receiving dialysis (21 studies, 2,943 participants: 70%, 95% CI 64%-76%). A number of symptoms were significantly (p < 0.05 after adjustment for multiple testing) less prevalent and/or less severe within the post-transplantation population, which may suggest attribution to CKD (fatigue, depression, itching, poor mobility, poor sleep, and dry mouth). Quality of life was commonly lower in patients on dialysis (36-Item Short Form Health Survey [SF-36] Mental Component Summary [MCS] 45.7 [95% CI 45.5-45.8]; SF-36 Physical Component Summary [PCS] 35.5 [95% CI 35.3-35.6]; 91 studies, 32,105 participants for MCS and PCS) than in other CKD populations (patients not on RRT: SF-36 MCS 66.6 [95% CI 66.5-66.6], p = 0.002; PCS 66.3 [95% CI 66.2-66.4], p = 0.002; 39 studies, 24,600 participants; transplant: MCS 50.0 [95% CI 49.9-50.1], p = 0.002; PCS 48.0 [95% CI 47.9-48.1], p = 0.002; 39 studies, 9,664 participants). Limitations of the analysis are the relatively few studies contributing to symptom severity estimates and inconsistent use of PROMs (different measures and time points) across the included literature, which hindered interpretation. CONCLUSIONS: The main findings highlight the considerable symptom and HRQOL burden associated with CKD. The synthesis provides a detailed overview of the symptom/HRQOL profile across clinical groups, which may support healthcare professionals when discussing, measuring, and managing the potential treatment burden associated with CKD. PROTOCOL REGISTRATION: PROSPERO CRD42020164737.

Norwegian Clinicians' Experiences of Learnability and Usability of SCID-II, SCID-5-PD and SCID-5-AMPD-I Interviews: A Sequential Multi-Group Qualitative Approach.

The DSM-5 presents two competing diagnostic frameworks for personality disorders: the standard categorical model and the Alternative Model of Personality Disorders (AMPD). The AMPD was initially criticized for being too complex and theory laden for clinical implementation. Though inter-rater reliability studies have contested initial claims of the model's complexity, little attention has been paid to how clinicians experience the usability and learnability of either model. We interviewed twenty Norwegian clinicians about their experiences with either the SCID-II/5-PD (n = 9), SCID-5-AMPD-I (n = 8), or both (n = 3). Separate thematic analyses were conducted for SCID-II/5-PD and SCID-5-AMPD-I groups, and group themes were compared. We identified four themes for each group, relating to required skills, training, challenges and information gained through the interview. We found that training and clinical experience were considered to be important for both interviews. Moreover, the SCID-5-AMPD-I was considered to rely more explicitly on theory specific to the development and content of the AMPD model in general and the LPFS specifically We also identified shared and unique challenges and shortcomings of each interview. We comment on how our findings relate to the debate surrounding the AMPD, and recommend development of clear training guidelines for both interviews.

The importance of harmonising diagnostic criteria sets for pathological grief.

Five diagnostic criteria sets for pathological grief are currently used in research. Studies evaluating their performance indicate that it is not justified to generalise findings regarding prevalence rates and predictive validity across studies using different diagnostic criteria of pathological grief. We provide recommendations to move the bereavement field forward.

Support for the higher-order factor structure of the WHODAS 2.0 self-report version in a Dutch outpatient psychiatric setting.

PURPOSE: Previous studies of the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) interview version suggested a second-order model, with a general disability factor and six factors on a lower level. The goal of this study is to investigate if we can find support for a similar higher-order factor structure of the 36-item self-report version of the WHODAS 2.0 in a Dutch psychiatric outpatient sample. We aim to give special attention to the differences between the non-working group sample and the working group sample. Additionally, we intend to provide preliminary norms for clinical interpretation of the WHODAS 2.0 scores in psychiatric settings. METHODS: Patients seeking specialized ambulatory treatment, primarily for depressive or anxiety symptoms, completed the WHODAS 2.0 as part of the initial interview. The total sample consisted of 770 patients with a mean age of 37.5 years (SD = 13.3) of whom 280 were males and 490 were females. Several factorial compositions (i.e., one unidimensional model and two second-order models) were modeled using confirmatory factor analysis (CFA). Descriptive statistics, model-fit statistics, reliability of the (sub)scales, and preliminary norms for interpreting test scores are reported. RESULTS: For the non-working group, the second-order model with a general disability factor and six factors on a lower level, provided an adequate fit. Whereas, for the working group, the second-order model with a general disability factor and seven factors on a lower level seemed more appropriate. The WHODAS 2.0 36-item self-report form showed adequate levels of reliability. Percentile ranks and normalized T-scores are provided to aid clinical evaluations. CONCLUSION: Our results lend support for a factorial structure of the WHODAS 2.0 36-item self-report version that is comparable to the interview version. While we conjecture that a seven-factor solution might give a better reflection of item content and item variance, further research is needed to assess the clinical relevance of such a model. At this point, we recommend using the second-order structure with six factors that matches past findings of the interview form.

A multi-center psychometric evaluation of the Severity Indices of Personality Problems 118 (SIPP-118): Do we really need all those facets?

PURPOSE: The Severity Indices of Personality Problems 118 (SIPP-118) is a self-report questionnaire that aims to measure core components of (mal)adaptive personality functioning that can change over time. In this study, we aimed to assess the facet strength of the 16 facets across three large clinical samples. METHODS: Data from Norwegian and Dutch psychiatric patients were analyzed in this international multi-center study (N1 = 2814, N2 = 4751, N3 = 2217). Bi-factor modeling was used to assess to what degree the SIPP items tap into an overall general factor. The incremental value (distinctiveness) of the facets was studied using proportional reduction in mean squared error (PRMSE) based statistics. RESULTS: The estimated model showed adequate fit. The explained common variance (ECV) attributable to the general factor equaled 50% for all three samples. All but two facets (stable self-image and frustration tolerance) showed sufficient levels of distinctiveness. The findings were observed to be comparable across the three samples. CONCLUSION: Our findings showed that the general factor was relatively weak, and the facets had a clear incremental value.

Psychometric Properties of the Externalizing Spectrum Inventory: Replication and Extension across Clinical and Non-Clinical Samples.

The Externalizing Spectrum Inventory aims at assessing personality features that underlie externalizing disorders such as substance abuse and antisocial behaviors. The objective was to replicate the psychometric properties of the 160-item Externalizing Spectrum Inventory in Dutch clinical and non-clinical samples. First, Cronbach's alpha, test-retest reliability and the factor structure were analyzed on a mixed sample of inpatients (n = 149), undergraduates (n = 227), and community participants (n = 178). The factor structure was evaluated through confirmatory and exploratory factor analyses; for the latter Parallel Analysis was used, based on Minimum Rank Factor Analysis. Next, the criterion validity was analyzed using the Aggression Questionnaire and the NEO-Five Factor Inventory as external measures. The Dutch Externalizing Spectrum Inventory subscales showed sufficient reliability (α=.68-.94; ICC=.68-.91), except in the undergraduate sample (α=.49-.96; ICC=.43-.97). The factor structure of the Externalizing Spectrum Inventory was not confirmed and the exploratory analysis yielded different factor solutions across samples. The criterion validity was supported with regard to trait aggression and partly supported with regard to the Five Factor Model. The results suggest that the ESI-160 and its original factor model can be used for prediction purposes. However, further research of the factor structure is strongly recommended.

Inventory of assessment practices in people with profound intellectual and multiple disabilities in three European countries.

BACKGROUND: Knowledge about the quality of assessment methods used in the support of people with profound intellectual and multiple disabilities (PIMD) is scarce. This study aimed to provide an overview of the assessment methods used in practice and to examine whether these instruments were studied for their psychometric properties for people with PIMD. METHOD: Professionals (N = 148) from three European countries completed a survey on assessment practices. We performed a literature search to find information about the psychometric properties of the instruments that were identified in the survey. RESULTS: Of the participants, 78.1% used assessments that were not developed for people with PIMD. Documentation on psychometric properties was found for 8 out of 116 instruments. CONCLUSIONS: Most of the instruments in use were not designed for people with PIMD, and information about their quality is lacking. Guidelines are needed regarding the use and development of assessment methods for people with PIMD.

Some recommendations for developing multidimensional computerized adaptive tests for patient-reported outcomes.

PURPOSE: Multidimensional item response theory and computerized adaptive testing (CAT) are increasingly used in mental health, quality of life (QoL), and patient-reported outcome measurement. Although multidimensional assessment techniques hold promises, they are more challenging in their application than unidimensional ones. The authors comment on minimal standards when developing multidimensional CATs. METHODS: Prompted by pioneering papers published in QLR, the authors reflect on existing guidance and discussions from different psychometric communities, including guidelines developed for unidimensional CATs in the PROMIS project. RESULTS: The commentary focuses on two key topics: (1) the design, evaluation, and calibration of multidimensional item banks and (2) how to study the efficiency and precision of a multidimensional item bank. The authors suggest that the development of a carefully designed and calibrated item bank encompasses a construction phase and a psychometric phase. With respect to efficiency and precision, item banks should be large enough to provide adequate precision over the full range of the latent constructs. Therefore CAT performance should be studied as a function of the latent constructs and with reference to relevant benchmarks. Solutions are also suggested for simulation studies using real data, which often result in too optimistic evaluations of an item bank's efficiency and precision. DISCUSSION: Multidimensional CAT applications are promising but complex statistical assessment tools which necessitate detailed theoretical frameworks and methodological scrutiny when testing their appropriateness for practical applications. The authors advise researchers to evaluate item banks with a broad set of methods, describe their choices in detail, and substantiate their approach for validation.

Interrater Reliability of the Structured Clinical Interview for the DSM-5 Alternative Model of Personality Disorders Module i: Level of Personality Functioning Scale.

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) presents an alternative model for personality disorders in which severity of personality pathology is evaluated by the Level of Personality Functioning Scale (LPFS). The Structured Interview for the DSM-5 Alternative Model for Personality Disorders, Module I (SCID-5-AMPD I) is a new tool for LPFS assessment, but its interrater reliability (IRR) has not yet been tested. Here we examined the reliability of the Norwegian translation of the SCID-5-AMPD I, applying two different designs: IRR assessment based on ratings of 17 video-recorded SCID-5-AMPD I interviews by five raters; and test-retest IRR based on interviews of 33 patients administered by two different raters within a short interval. For the video-based investigation, intraclass correlation coefficient (ICC) values ranged from .77 to .94 for subdomains, .89 to .95 for domains, and .96 for total LPFS. For the test-retest investigation, ICC ranged from .24 to .72 for subdomains, .59 to .90 for domains, and .75 for total LPFS. The test-retest study revealed questionable reliability estimates for some subdomains. However, overall the level of personality functioning was measured with a sufficient degree of IRR when assessed by the SCID-5-AMPD I.

Item usage in a multidimensional computerized adaptive test (MCAT) measuring health-related quality of life.

PURPOSE: Examining item usage is an important step in evaluating the performance of a computerized adaptive test (CAT). We study item usage for a newly developed multidimensional CAT which draws items from three PROMIS domains, as well as a disease-specific one. METHODS: The multidimensional item bank used in the current study contained 194 items from four domains: the PROMIS domains fatigue, physical function, and ability to participate in social roles and activities, and a disease-specific domain (the COPD-SIB). The item bank was calibrated using the multidimensional graded response model and data of 795 patients with chronic obstructive pulmonary disease. To evaluate the item usage rates of all individual items in our item bank, CAT simulations were performed on responses generated based on a multivariate uniform distribution. The outcome variables included active bank size and item overuse (usage rate larger than the expected item usage rate). RESULTS: For average θ-values, the overall active bank size was 9-10%; this number quickly increased as θ-values became more extreme. For values of -2 and +2, the overall active bank size equaled 39-40%. There was 78% overlap between overused items and active bank size for average θ-values. For more extreme θ-values, the overused items made up a much smaller part of the active bank size: here the overlap was only 35%. CONCLUSIONS: Our results strengthen the claim that relatively short item banks may suffice when using polytomous items (and no content constraints/exposure control mechanisms), especially when using MCAT.

The COPD-SIB: a newly developed disease-specific item bank to measure health-related quality of life in patients with chronic obstructive pulmonary disease.

BACKGROUND: Health-related quality of life (HRQoL) is widely used as an outcome measure in the evaluation of treatment interventions in patients with chronic obstructive pulmonary disease (COPD). In order to address challenges associated with existing fixed-length measures (e.g., too long to be used routinely, too short to ensure both content validity and reliability), a COPD-specific item bank (COPD-SIB) was developed. METHODS: Items were selected based on literature review and interviews with Dutch COPD patients, with a strong focus on both content validity and item comprehension. The psychometric quality of the item bank was evaluated using Mokken Scale Analysis and parametric Item Response Theory, using data of 666 COPD patients. RESULTS: The final item bank contains 46 items that form a strong scale, tapping into eight important themes that were identified based on literature review and patient interviews: Coping with disease/symptoms, adaptability; Autonomy; Anxiety about the course/end-state of the disease, hopelessness; Positive psychological functioning; Situations triggering or enhancing breathing problems; Symptoms; Activity; Impact. CONCLUSIONS: The 46-item COPD-SIB has good psychometric properties and content validity. Items are available in Dutch and English. The COPD-SIB can be used as a stand-alone instrument, or to inform computerised adaptive testing.

Using the Three-Step Test Interview to understand how patients perceive the St. George's Respiratory Questionnaire for COPD patients (SGRQ-C).

PURPOSE: The aim of this study was to assess the experiences of patients with chronic obstructive pulmonary disease (COPD) while they were completing the St. George's Respiratory Questionnaire for COPD patients (SGRQ-C), using qualitative research methods. METHODS: Twenty Dutch COPD patients were recruited through pulmonary physicians [13 women; mean age = 63.3 years (SD = 11.4)]. A trained interviewer applied the Three-Step Test Interview which allowed the interviewer to follow the thought process of the patient filling out the SGRQ-C. The official Dutch translation of the SGRQ-C was used. RESULTS: Patients missed a recall period for the Symptoms subscale; were uncertain how to interpret specific words and phrases like "good days", "games", and "housework"; were confused by long-item stems that included a list of activities; and were frustrated by the dichotomous format used for the majority of SGRQ-C items (true/false). CONCLUSIONS: Overall, patients were satisfied with the SGRQ-C. Nevertheless, making minor adjustments could further increase its quality. This includes reintroducing a recall period in the first set of items such as used in the previous version and splitting up items consisting of multiple activities. Furthermore, we recommend using the same response format (4 or 5 response categories) for all items.

Identifying key domains of health-related quality of life for patients with chronic obstructive pulmonary disease: interviews with healthcare professionals.

PURPOSE: The aim of this paper is to identify which domains of health-related quality of life (HRQoL) are most important for patients with chronic obstructive pulmonary disease (COPD), from the perspective of healthcare professionals (HCPs). METHODS: Thirteen Dutch HCPs [six pulmonologists, three pulmonology nurse practitioners, two physiotherapists and two general practitioners; 9 men; mean age 51.0 (SD = 10.6) years; mean years of experience 12.1 (SD = 7.2)] specialized in the field of COPD were recruited. The only inclusion criterion was that the HCP had to have extensive experience in treating COPD patients. The face-to-face interviews took 30-40 min. RESULTS: Physical health emerged as the most important theme from the spontaneous statements that HCPs made when asked about HRQoL in relation to COPD, closely followed by social health and coping with COPD-related complaints and restrictions. The most frequently selected PROMIS domains were fatigue, physical function, emotional support and depression. If the related domains satisfaction with participation in social roles and activities and ability to participate in social roles and activities were to be combined, it would come in second place after fatigue. CONCLUSION: When comparing the domains chosen by HCPs to the ones chosen by patients in a recent study, there is a high degree of agreement, with the exception of depression. We argue that it is important to take into account both patient and HCP perspective when developing/selecting HRQoL instruments. Our results may be used to inform domain selection to measure HRQoL in patients with COPD, as well as instrument development.

The St George's Respiratory Questionnaire revisited: a psychometric evaluation.

PURPOSE: The St George's Respiratory Questionnaire (SGRQ) has clearly acquired the status of legacy questionnaire for measuring health-related quality of life in patients with chronic obstructive pulmonary disease (COPD). The main aim of this study was to assess the underlying dimensionality of the SGRQ and to investigate the added value of the empirical weights used to calculate total scores. METHODS: The official Dutch translation of the SGRQ was completed by 444 COPD patients participating in two clinical studies. These data were used for secondary data analysis in this study. Three complementary statistical methods were used to assess dimensionality: Mokken scale analysis (MSA), parametric multidimensional item response theory (IRT) and bifactor analysis. Additionally, the original SGRQ weighting procedure was compared to IRT-based weighting. RESULTS: The results of the MSA and multidimensional item response theory (MIRT) pointed toward a unidimensional structure. The bifactor analyses indicated that there was a strong general factor, but the group factors did have additional value. Nineteen items performed poorly in the MSA, MIRT analysis or both. Shortening the scale from 50 to 31 items did not negatively impact measurement precision. SGRQ total score and IRT-derived scores correlated strongly, 0.90 for the one-parameter model and 0.99 for the two-parameter model. CONCLUSION: The SGRQ contains some multidimensionality, but an abbreviated version can be used as a unidimensional tool in patients with COPD. Subscale scores should be used with care. SGRQ total scores correlated highly with IRT-based scores, and thus, the weighting methods may be used interchangeably to calculate total scores.

Psychiatric characteristics in transsexual individuals: multicentre study in four European countries.

BACKGROUND: Research into the relationship between gender identity disorder and psychiatric problems has shown contradictory results. AIMS: To investigate psychiatric problems in adults fulfilling DSM-IV-TR criteria for a diagnosis of gender identity disorder. METHOD: Data were collected within the European Network for the Investigation of Gender Incongruence using the Mini International Neuropsychiatric Interview - Plus and the Structured Clinical Interview for DSM-IV Axis II Disorders (n = 305). RESULTS: In 38% of the individuals with gender identity disorder a current DSM-IV-TR Axis I diagnosis was found, mainly affective disorders and anxiety disorders. Furthermore, almost 70% had a current and lifetime diagnosis. All four countries showed a similar prevalence, except for affective and anxiety disorders, and no difference was found between individuals with early-onset and late-onset disorder. An Axis II diagnosis was found in 15% of all individuals with gender identity disorder, which is comparable to the general population. CONCLUSIONS: People with gender identity disorder show more psychiatric problems than the general population; mostly affective and anxiety problems are found.