Multivariate modelling of responses to conditional items: New possibilities for latent class analysis

Questionnaire data may contain missing values because certain questions do not apply to all respondents. For instance, questions addressing particular attributes of a symptom, such as frequency, triggers or seasonality, are only applicable to those who have experienced the symptom, while for those who have not, responses to these items will be missing. This missing information does not fall into the category 'missing by design', rather the features of interest do not exist and cannot be measured regardless of survey design. Analysis of responses to such conditional items is therefore typically restricted to the subpopulation in which they apply. This article is concerned with joint multivariate modelling of responses to both unconditional and conditional items without restricting the analysis to this subpopulation. Such an approach is of interest when the distributions of both types of responses are thought to be determined by common parameters affecting the whole population. By integrating the conditional item structure into the model, inference can be based both on unconditional data from the entire population and on conditional data from subjects for whom they exist. This approach opens new possibilities for multivariate analysis of such data. We apply this approach to latent class modelling and provide an example using data on respiratory symptoms (wheeze and cough) in children. Conditional data structures such as that considered here are common in medical research settings and, although our focus is on latent class models, the approach can be applied to other multivariate models.

Comprehensive assessment of gesture production: a new test of upper limb apraxia (TULIA)

BACKGROUND: Only few standardized apraxia scales are available and they do not cover all domains and semantic features of gesture production. Therefore, the objective of the present study was to evaluate the reliability and validity of a newly developed test of upper limb apraxia (TULIA), which is comprehensive and still short to administer. METHODS: The TULIA consists of 48 items including imitation and pantomime domain of non-symbolic (meaningless), intransitive (communicative) and transitive (tool related) gestures corresponding to 6 subtests. A 6-point scoring method (0-5) was used (score range 0-240). Performance was assessed by blinded raters based on videos in 133 stroke patients, 84 with left hemisphere damage (LHD) and 49 with right hemisphere damage (RHD), as well as 50 healthy subjects (HS). RESULTS: The clinimetric findings demonstrated mostly good to excellent internal consistency, inter- and intra-rater (test-retest) reliability, both at the level of the six subtests and at individual item level. Criterion validity was evaluated by confirming hypotheses based on the literature. Construct validity was demonstrated by a high correlation (r = 0.82) with the De Renzi-test. CONCLUSION: These results show that the TULIA is both a reliable and valid test to systematically assess gesture production. The test can be easily applied and is therefore useful for both research purposes and clinical practice.

The HeartQoL: Part II. Validation of a new core health-related quality of life questionnaire for patients with ischemic heart disease

Background: Evaluation of health-related quality of life (HRQL) is important in improving the quality of patient care. The aim of this study was to determine the psychometric properties of the HeartQoL in patients with ischemic heart disease (IHD), specifically angina, myocardial infarction (MI), or ischemic heart failure. Methods: Data for the interim validation of the HeartQoL questionnaire were collected in (a) a cross-sectional survey and (b) a prospective substudy of patients undergoing either a percutaneous coronary intervention (PCI) or referred to cardiac rehabilitation (CR) and were then analyzed to determine the reliability, validity, and responsiveness of the HeartQoL questionnaire. Results: We enrolled 6384 patients (angina, n = 2111, 33.1%; MI, n = 2351, 36.8%; heart failure, n = 1922, 30.1%) across 22 countries speaking 15 languages in the cross-sectional study and 730 patients with IHD in the prospective substudy. The HeartQoL questionnaire comprises 14-items with physical and emotional subscales and a global score (range 0–3 (poor to better HRQL). Cronbach’s α was consistently ≥0.80; convergent validity correlations between similar HeartQoL and SF-36 subscales were significant (r ≥ 0.60, p < 0.001); discriminative validity was confirmed with predictor variables: health transition, anxiety, depression, and functional status. HeartQoL score changes following either PCI or CR were significant (p < 0.001) with effect sizes ranging from 0.37–0.64. Conclusion: The HeartQoL questionnaire is reliable, valid, and responsive to change allowing clinicians and researchers to (a) assess baseline HRQL, (b) make between-diagnosis comparisons of HRQL, and (c) evaluate change in HRQL in patients with angina, MI, or heart failure with a single IHD-specific HRQL instrument.

The HeartQoL: Part I. Development of a new core health-related quality of life questionnaire for patients with ischemic heart disease

Background: Evaluation of health-related quality of life (HRQL) is important in improving the quality of patient care. Methods: The HeartQoL Project, with cross-sectional and longitudinal phases, was designed to develop a core ischemic heart disease (IHD) specific HRQL questionnaire, to be called the HeartQoL, for patients with angina, myocardial infarction (MI), or ischemic heart failure. Patients completed a battery of questionnaires and Mokken scaling analysis was used to identify items in the HeartQoL questionnaire. Results: We enrolled 6384 patients (angina, n = 2111, 33.1%; MI, n = 2351, 36.8%; heart failure, n = 1922, 30.1%) across 22 countries and 15 languages. The HeartQoL questionnaire comprises 14-items with 10-item physical and 4-item emotional subscales which are scored from 0 (poor HRQL) to 3 (better HRQL) with a global score if needed. The mean baseline HeartQoL global score was 2.2 (±0.5) in the total group and was different (p < 0.001) by diagnosis (MI, 2.4 ± 0.5; angina, 2.2 ± 0.6; and heart failure, 2.1 ± 0.6). Conclusion: The HeartQoL questionnaire, with global and subscale scores, has the potential to allow clinicians and researchers to (a) assess baseline HRQL, (b) make between-diagnosis comparisons of HRQL, and (c) evaluate change in HRQL in patients with angina, MI, or heart failure with a single IHD-specific HRQL instrument.

Item Sum: A New Technique for Asking Quantitative Sensitive Questions

This article contributes to an ongoing debate about how to measure sensitive topics in population surveys. We propose a novel technique that can be applied to the measurement of quantitative sensitive variables: the item sum technique (IST). This method is closely related to the item count technique, which was developed for the measurement of dichotomous sensitive items. First, we provide a description of our new technique and discuss how data collected by the IST can be analyzed. Second, we present the results of a CATI survey on undeclared work in Germany, in which the IST has been applied. Using an experimental design, we compare the IST to direct questioning. Our empirical results indicate that the IST is a promising data-collection technique for sensitive questions. We conclude by discussing the limitations of the new technique and outlining possible improvements for future studies.

The dementia cognitive fluctuation scale, a new psychometric test for clinicians to identify cognitive fluctuations in people with dementia.

OBJECTIVES Cognitive fluctuation (CF) is a common feature of dementia and a core diagnostic symptom for dementia with Lewy bodies (DLB). CF remains difficult to accurately and reliably detect clinically. This study aimed to develop a psychometric test that could be used by clinicians to facilitate the identification of CF and improve the recognition and diagnosis of DLB and Parkinson disease, and to improve differential diagnosis of other dementias. METHODS We compiled a 17-item psychometric test for identifying CF and applied this measure in a cross-sectional design. Participants were recruited from the North East of England, and assessments were made in individuals' homes. We recruited people with four subtypes of dementia and a healthy comparison group, and all subjects were administered this pilot scale together with other standard ratings. The psychometric properties of the scale were examined with exploratory factor analysis. We also examined the ability of individual items to identify CF to discriminate between dementia subtypes. The sensitivity and specificity of discriminating items were explored along with validity and reliability analyses. RESULTS Participants comprised 32 comparison subjects, 30 people with Alzheimer disease, 30 with vascular dementia, 29 with DLB, and 32 with dementia associated with Parkinson disease. Four items significantly discriminated between dementia groups and showed good levels of sensitivity (range: 78.6%-80.3%) and specificity (range: 73.9%-79.3%). The scale had very good levels of test-retest (Cronbach's alpha: 0.82) and interrater (0.81) reliabilities. The four items loaded onto three different factors. These items were: 1) marked differences in functioning during the daytime; 2) daytime somnolence; 3) daytime drowsiness; and 4) altered levels of consciousness during the day. CONCLUSIONS We identified four items that provide valid, sensitive, and specific questions for reliably identifying CF and distinguishing the Lewy body dementias from other major causes of dementia (Alzheimer disease and vascular dementia).

A new universal, standardized implant database for product identification: a unique tool for arthroplasty registries.

INTRODUCTION Every joint registry aims to improve patient care by identifying implants that have an inferior performance. For this reason, each registry records the implant name that has been used in the individual patient. In most registries, a paper-based approach has been utilized for this purpose. However, in addition to being time-consuming, this approach does not account for the fact that failure patterns are not necessarily implant specific but can be associated with design features that are used in a number of implants. Therefore, we aimed to develop and evaluate an implant product library that allows both time saving barcode scanning on site in the hospital for the registration of the implant components and a detailed description of implant specifications. MATERIALS AND METHODS A task force consisting of representatives of the German Arthroplasty Registry, industry, and computer specialists agreed on a solution that allows barcode scanning of implant components and that also uses a detailed standardized classification describing arthroplasty components. The manufacturers classified all their components that are sold in Germany according to this classification. The implant database was analyzed regarding the completeness of components by algorithms and real-time data. RESULTS The implant library could be set up successfully. At this point, the implant database includes more than 38,000 items, of which all were classified by the manufacturers according to the predefined scheme. Using patient data from the German Arthroplasty Registry, several errors in the database were detected, all of which were corrected by the respective implant manufacturers. CONCLUSIONS The implant library that was developed for the German Arthroplasty Registry allows not only on-site barcode scanning for the registration of the implant components but also its classification tree allows a sophisticated analysis regarding implant characteristics, regardless of brand or manufacturer. The database is maintained by the implant manufacturers, thereby allowing registries to focus their resources on other areas of research. The database might represent a possible global model, which might encourage harmonization between joint replacement registries enabling comparisons between joint replacement registries.

New Clinical Indications for (18)F/(11)C-choline, New Tracers for Positron Emission Tomography and a Promising Hybrid Device for Prostate Cancer Staging: A Systematic Review of the Literature

CONTEXT Radiolabelled choline positron emission tomography has changed the management of prostate cancer patients. However, new emerging radiopharmaceutical agents, like radiolabelled prostate specific membrane antigen, and new promising hybrid imaging will begin new challenges in the diagnostic field. OBJECTIVE The continuous evolution in nuclear medicine has led to the improvement in the detection of recurrent prostate cancer (PCa), particularly distant metastases. New horizons have been opened for radiolabelled choline positron emission tomography (PET)/computed tomography (CT) as a guide for salvage therapy or for the assessment of systemic therapies. In addition, new tracers and imaging tools have been recently tested, providing important information for the management of PCa patients. Herein we discuss: (1) the available evidence in literature on radiolabelled choline PET and their recent indications, (2) the role of alternative radiopharmaceutical agents, and (3) the advantages of a recent hybrid imaging device (PET/magnetic resonance imaging) in PCa. EVIDENCE ACQUISITION Data from recently published (2010-2015), original articles concerning the role of choline PET/CT, new emerging radiotracers, and a new imaging device are analysed. This review is reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. EVIDENCE SYNTHESIS In the restaging phase, the detection rate of choline PET varies between 4% and 97%, mainly depending on the site of recurrence and prostate-specific antigen levels. Both 68gallium (68Ga)-prostate specific membrane antigen and 18F-fluciclovine are shown to be more accurate in the detection of recurrent disease as compared with radiolabelled choline PET/CT. Particularly, Ga68-PSMA has a detection rate of 50% and 68%, respectively for prostate-specific antigen levels < 0.5ng/ml and 0.5-2ng/ml. Moreover, 68Ga- PSMA PET/magnetic resonance imaging demonstrated a particularly higher accuracy in detecting PCa than PET/CT. New tracers, such as radiolabelled bombesin or urokinase-type plasminogen activator receptor, are promising, but few data in clinical practice are available today. CONCLUSIONS Some limitations emerge from the published papers, both for radiolabelled choline PET/CT and also for new radiopharmaceutical agents. Efforts are still needed to enhance the impact of published data in the world of oncology, in particular when new radiopharmaceuticals are introduced into the clinical arena. PATIENT SUMMARY In the present review, the authors summarise the last evidences in clinical practice for the assessment of prostate cancer, by using nuclear medicine modalities, like positron emission tomography/computed tomography and positron emission tomography/magnetic resonance imaging.