Cardiac troponin T degradation in end-stage renal disease patients appears to occur in vivo

Background

Cardiac troponin T (cTnT) is a cornerstone biomarker for diagnosing myocardial infarction (MI). However, since the introduction of the high-sensitivity assays, cardiac troponins are also measured in pathologies with cardiac risk factors, such as end-stage renal disease (ESRD), making it more difficult for clinicians to diagnose MI. Previous studies of our group identified specific larger cTnT proteoforms for the acute phase of MI, while a study in serum of ESRD patients showed solely small cTnT fragments. However, others allocated the small cTnT fragments in serum of ESRD patients to a pre-analytic effect due to abundant thrombin generation in serum, as thrombin is known to cause fragmentation of cTnT.

Purpose

This study investigated the effect of multiple anticoagulation methods on cTnT proteoforms in vitro and in the blood of ESRD patients.

Methods

First, cTnT negative serum and lithium-heparinized (LH), ethylenediaminetetraacetic-acid (EDTA), and hirudin plasma tubes were spiked with human cTnT standard, incubated at 37°C till 48 hours, and analysed with Western Blotting using anti-cTnT Roche antibodies. Second, similar blood tubes were collected from ESRD patients (n=10) conform the Declaration of Helsinki, patient samples and spiked cTnT standards were separated using gel filtration chromatography (GFC) and cTnT was subsequently analysed using the Cobas 6000 analyser.

Results

After 48 hours of in vitro incubation of cTnT in hirudin plasma, no cTnT degradation was observed, while LH only showed minor degradation of 10% from intact 40 kDa cTnT to 29 kDa fragments (figure 1). Also, for both EDTA and serum, a time-dependent degradation from 40 kDa cTnT to 29 kDa fragments to 15–18 kDa fragments was observed. Moreover, in ESRD patients, GFC elution profiles of all blood tubes revealed that 85–98% of cTnT corresponded to small 15–18 kDa fragments (41–42 mL), while 2–15% were 29/40 kDa cTnT forms (27–28 mL). For comparison, standards of ternary T-I-C complex and intact cTnT eluted at 21 mL and 28 mL, respectively.

Conclusions

The extent of cTnT degradation in vitro is dependent on the anticoagulation method of the blood tubes, with absence of degradation exclusively in hirudin plasma. Since in ESRD patients for all blood tubes mainly small 15–18 kDa cTnT fragments were found, including hirudin plasma, cTnT degradation appears to occur in vivo. This observation supports the hypothesis that larger cTnT proteoforms might indeed be specific for the acute phase of MI, thereby supporting the opportunity for developing a more specific cTnT method.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): ZonMw Veni grant

Reliability and validity of an extended clinical examination

INTRODUCTION

An extended clinical examination (ECE) was administered to 85 final year medical students at the Radboud University Medical Centre in the Netherlands. The aim of the study was to determine the psychometric quality and the suitability of the ECE as a measurement tool to assess the clinical proficiency of eight separate clinical skills.

METHODS

Generalizability studies were conducted to determine the generalizability coefficient and the sources of variance of the ECE. An additional D-study was performed to estimate the generalizability coefficients with altering numbers of stations.

RESULTS

The largest sources of variance were found in skill difficulties (36.18%), the general error term (26.76%) and in the rank ordering of skill difficulties across the stations (21.89%). The generalizability coefficient of the entire ECE was above the 0.70 lower bound (G = 0.74). D studies showed that the separate skills could yield sufficient G coefficients in seven out of eight skills, if the ECE was lengthened from 8 to 14 stations.

DISCUSSION

The ECE proved to be a reliable clinical assessment that enables examinees to compose a clinical reasoning path through self-obtained data. The ECE can also be used as an assessment tool for separate clinical skills.

Teacher attitudes toward dyslexia: effects on teacher expectations and the academic achievement of students with dyslexia

The present study examined teacher attitudes toward dyslexia and the effects of these attitudes on teacher expectations and the academic achievement of students with dyslexia compared to students without learning disabilities. The attitudes of 30 regular education teachers toward dyslexia were determined using both an implicit measure and an explicit, self-report measure. Achievement scores for 307 students were also obtained. Implicit teacher attitudes toward dyslexia related to teacher ratings of student achievement on a writing task and also to student achievement on standardized tests of spelling but not math for those students with dyslexia. Self-reported attitudes of the teachers toward dyslexia did not relate to any of the outcome measures. Neither the implicit nor the explicit measures of teacher attitudes related to teacher expectations. The results show implicit attitude measures to be a more valuable predictor of the achievement of students with dyslexia than explicit, self-report attitude measures.

Checking the checklist: a content analysis of expert- and evidence-based case-specific checklist items

OBJECTIVES

Research on objective structured clinical examinations (OSCEs) is extensive. However, relatively little has been written on the development of case-specific checklists on history taking and physical examination. Background information on the development of these checklists is a key element of the assessment of their content validity. Usually, expert panels are involved in the development of checklists. The objective of this study is to compare expert-based items on OSCE checklists with evidence-based items identified in the literature.

METHODS

Evidence-based items covering both history taking and physical examination for specific clinical problems and diseases were identified in the literature. Items on nine expert-based checklists for OSCE examination stations were evaluated by comparing them with items identified in the literature. The data were grouped into three categories: (i) expert-based items; (ii) evidence-based items, and (iii) evidence-based items with a specific measure of their relevance.

RESULTS

Out of 227 expert-based items, 58 (26%) were not found in the literature. Of 388 evidence-based items found in the literature, 219 (56%) were not included in the expert-based checklists. Of these 219 items, 82 (37%) had a specific measure of importance, such as an odds ratio for a diagnosis, making that diagnosis more or less probable.

CONCLUSIONS

Expert-based, case-specific checklist items developed for OSCE stations do not coincide with evidence-based items identified in the literature. Further research is needed to ascertain what this inconsistency means for test validity.

The clinical skills assessment for international medical graduates in The Netherlands

AIM

A need was felt to improve the quality of admission and licensing procedures for international medical graduates in The Netherlands.

METHOD

A clinical skills assessment was designed as part of a new procedure to realize a high-stakes, fair, transparent, and a time-limited path of admission for international medical graduates to the Dutch health care system. Additionally, it should provide a well-founded advice about length and content of additional medical training, should this be indicated by the outcome of the assessment.

RESULTS

The clinical skills assessment procedure was developed as a Dutch variant of the "Step 2 Clinical Skills examination" of the Educational Commission for Foreign Medical Graduates (ECFMG) in collaboration with the United States National Board of Medical Examiners, which has a well-documented validity and reliability. The experience with the new procedure is yet limited, but enough to warrant a report.

DISCUSSION

Worldwide, a number of countries have developed such high-stake assessment procedures, but they show little uniformity and transparency. By describing the design and development of our procedure, we do not pretend to set a standard, but we hope to contribute to more fair, accurate and uniform approaches for doctors moving from one country to another.

The structure of medical competence and results of an OSCE

BACKGROUND

Medical competence is a central concept in medical education. Educational efforts in medical training are directed at the achievement of a maximal medical competence. The concept of the structure of medical competence (multidimensional or one-dimensional with strongly interrelated competences) therefore affects the educational developments and assessment procedures.

PURPOSE

To examine the applicability of a one or more dimensional character of medical competence in student assessments, by analysing the results of 356 students in the history taking station of an objective structured clinical examination (OSCE), in relation to other assessment procedures.

METHODS

The performances of 356 students in a history taking station of an OSCE were analysed. Analyses of the checklist scores were aimed at the dimensionality of history taking skills. External criteria were used to test the validity of the scores on the checklist.

RESULTS

The analyses of the scores on the history taking checklist indicated at least five dimensions of history taking skills: the frequency of patient-centred skills, the quality of performance of patient-centred skills, complaint-oriented skills, general social skills, and the provision of procedural information.

CONCLUSION

Medical competence, as a subject of assessment, can be seen as a multifaceted construct. This study shows that history taking alone might be composed of five different dimensions, suggesting that medical competence in respect of assessment might be viewed as a multifaceted construct which in that sense has implications for the assessment of medical competence.

Assessing orientations to learning to teach

BACKGROUND

An important purpose of teacher education is that student teachers develop and change their existing knowledge on learning and teaching. Research on how student teachers variously engage in this process is scarce. In a previous study of 30 student teachers, we identified five different orientations to learning to teach.

AIMS

Our aim was to extend the results of the previous study by developing an instrument to assess orientations to learning to teach at a larger scale. The development and psychometric properties of the instrument are discussed. The results with respect to how student teachers learn are compared to the results of the qualitative study.

SAMPLE

Participants in this study were 169 secondary student teachers from three institutes which had all adopted an initial in-service model of learning to teach.

METHODS

On the basis of extensive qualitative study, a questionnaire was developed to assess individual differences in learning to teach. Factor-, reliability-, and nonparametric scalability analyses were performed to identify reliable scales. Cluster analysis was used to identify groups of students with similar orientations to learning to teach.

RESULTS

Eight scales covering cognitive, regulative and affective aspects of student teachers' learning were identified. Cluster analysis indicates that the instrument discriminates well between student teachers. Four of the five previously found patterns were found again.

CONCLUSIONS

The four orientations found in relatively uniform learning environments indicate that student teachers need differential support in their learning. Although the instrument measures individual differences in a reliable way, it is somewhat one-sided in the sense that items representing constructive ways of learning dominate. New items forming a broader range of scales should be created.