Isolation and characterization of reference standard candidates for cocaine and benzoylecgonine obtained from illicit substances seized

The area of forensic chemistry has been growing and developing as a line of research due to the high demands of public safety that require increasingly reliable results due to their importance in criminalistics. In this way, the development of new technologies that help this area, whether in the identification and quantification of drugs or the fight against fraud, becomes promising. In this context, the present work explored the production of reference standards from the purification of cocaine/crack samples seized by the Civil Police of the State of Espírito Santo. Cocaine was purified using chromatographic techniques, and benzoylecgonine was synthesized from purified cocaine. All substances were characterized by ultra-high-resolution mass spectrometry and nuclear magnetic resonance. Homogeneity and stability studies were also performed with benzoylecgonine, and the results were evaluated using analysis of variance (ANOVA). Cocaine and benzoylecgonine showed purities of 98.37% and 96.34%, respectively. The homogeneity of the batch, short-term stability, and other parameters were also evaluated, which together indicate this proposal as promising in the development of reference standards for drugs of abuse from samples seized by the Brazilian forensic police.

Selecting a birth weight standard for an indigenous population in a LMIC: A prospective comparative study

OBJECTIVES

The aim of the present study was to compare birth weight (BW) distribution and proportion of BWs below or above specified percentiles in low-risk singleton pregnancies in healthy South African (SA) women of mixed ancestry with expected values according to four BW references and to determine the physiological factors affecting BW.

METHODS

This was an ancillary study of a prospective multinational cohort study, involving 7060 women recruited between August 2007 and January 2015 in two townships of Cape Town, characterized by low socioeconomic status, and high levels of drinking and smoking. Detailed information about maternal and pregnancy characteristics, including harmful exposures, was gathered prospectively, allowing us to select healthy women with uncomplicated pregnancies without any known harmful exposures. In this cohort we compared the median BW and the proportion of BWs P90, 95 and 97 according to four reference standards (INTERGROWTH-21st, customized according to the method described by Mickolajczyk, Fetal Medicine Foundation and revised Fenton reference) with expected values. Appropriate parametric and nonparametric tests were used, and sensitivity analysis was performed for infant sex, first trimester bookings and women of normal body mass index (BMI). Multiple regression was used to explore effects of confounders. Written consent and ethics approval was obtained.

RESULTS

The cohort included 739 infants. The INTERGROWTH-21st standard was closest for the actual BW-distribution and categories. Below-expected BW was associated with boys, younger, shorter, leaner women, lower parity and gravidity. Actual BW was significantly influenced by maternal weight, BMI, parity and gestational age.

CONCLUSION

Of the four references assessed in this study, the INTERGROWTH-21st standard was closest for the actual BW distribution. Maternal variables significantly influence BW.

Collaborative study for the establishment of Ph. Eur. Biological Reference Preparation for Human tetanus immunoglobulin batch 2

This publication describes the outcome of a project to develop a replacement European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) for Human tetanus immunoglobulin (TIg) as well as for the World Health Organization (WHO) International Standard (IS) for Tetanus Immunoglobulin, Human. Bulk TIg was kindly provided by a European manufacturer and was used to prepare the candidate standard. The candidate standard was freeze-dried and calibrated in an international collaborative study jointly co-ordinated by the Medicines & Healthcare products Regulatory Agency (MHRA) and the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe). The results of this study show that there was good agreement between laboratories for the potency estimates obtained for the candidate standard relative to the current WHO IS/Ph. Eur. BRP. The study also demonstrated that the candidate standard is suitable for use in Ph. Eur. assays for potency testing of TIg products and there was good agreement in the potency estimates obtained using the different assay methods included in the study. Accelerated degradation studies performed at the MHRA over a period of 4 years suggest that the freeze-dried candidate standard will be very stable. The candidate standard was established as Ph. Eur. BRP for Human tetanus immunoglobulin, batch 2 with an assigned potency of 45 IU/ampoule. The same preparation was also adopted by the WHO Expert Committee on Biological Standardization (ECBS) to serve as the WHO 2nd IS for Tetanus Immunoglobulin, Human (13/240).

Missing values and inconclusive results in diagnostic studies - A scoping review of methods

Most diagnostic studies exclude missing values and inconclusive results from the analysis or apply simple methods resulting in biased accuracy estimates. This may be due to the lack of availability or awareness of appropriate methods. This scoping review aimed to provide an overview of strategies to handle missing values and inconclusive results in the reference standard or index test in diagnostic accuracy studies. Conducting a systematic literature search in MEDLINE, Cochrane Library, and Web of Science, we could identify many articles proposing methods for addressing missing values in the reference standard. There are also several articles describing methods regarding missing values or inconclusive results in the index test. The latter encompass imputation, frequentist and Bayesian likelihood, model-based, and latent class methods. While methods for missing values in the reference standard are regularly applied in practice, this is not true for methods addressing missing values and inconclusive results in the index test. Our comprehensive overview and description of available methods may raise further awareness of these methods and will enhance their application. Future research is needed to compare the performance of these methods under different conditions to give valid and robust recommendations for their usage in various diagnostic accuracy research scenarios.

Reference Standards for Digital Infrared Thermography Measuring Surface Temperature of the Upper Limbs

(1) Background: although digital infrared thermographic imaging (DITI) is used for diverse medical conditions of the upper limbs, no reference standards have been established. This study aims to establish reference standards by analyzing DITI results of the upper limbs. (2) Methods: we recruited 905 healthy Korean adults and conducted thermography on six regions (dorsal arm, ventral arm, lateral arm, medial arm, dorsal hand, and ventral hand region). We analyzed the data based on the proximity of regions of interest (ROIs), sex, and age. (3) Results: the average temperature (°C) and temperature discrepancy between the right and the left sides (ΔT) of each ROI varied significantly (p < 0.001), ranging from 28.45 ± 5.71 to 29.74 ± 5.14 and from 0.01 ± 0.49 to 0.15 ± 0.62, respectively. The temperature decreased towards the distal ROIs compared to proximal ROIs. The average temperatures of the same ROIs were significantly higher for men than women in all regions (p < 0.001). Across all regions, except the dorsal hand region, average temperatures tended to increase with age, particularly in individuals in their 30s and older (p < 0.001). (4) Conclusions: these data could be used as DITI reference standards to identify skin temperature abnormalities of the upper limbs. However, it is important to consider various confounding factors, and further research is required to validate the accuracy of our results under pathological conditions.

The Delirium Interview as a new reference standard in studies on delirium assessment tools

BACKGROUND

The reference standard in studies on delirium assessment tools is usually based on the clinical judgment of only one delirium expert and may be concise, unstandardized, or not specified at all. This multicenter study investigated the performance of the Delirium Interview, a new reference standard for studies on delirium assessment tools allowing classification of delirium based on written reports.

METHODS

We tested the diagnostic accuracy of our standardized Delirium Interview by comparing delirium assessments of the reported results with live assessments. Our reference, the live assessment, was performed by two delirium experts and one well-trained researcher who registered the results. Their delirium assessment was compared to the majority vote of three other independent delirium experts who judged the rapportage of the Delirium Interview. Our total pool consisted of 13 delirium experts with an average of 13 ± 8 years of experience.

RESULTS

We included 98 patients (62% male, mean age 69 ± 12 years), of whom 56 (57%) intensive care units (ICUs) patients, 22 (39%) patients with a Richmond Agitation Sedation Scale (RASS) < 0 and 26 (27%) non-verbal assessments. The overall prevalence of delirium was 28%. The Delirium Interview had a sensitivity of 89% (95% confidence interval [CI]: 71%-98%) and specificity of 82% (95% CI: 71%-90%), compared to the diagnosis of an independent panel of two delirium experts and one researcher who examined the patients themselves. Negative and positive predictive values were 95% (95% CI: 86%-0.99%), respectively, 66% (95% CI: 49%-80%). Stratification into ICU and non-ICU patients yielded similar results.

CONCLUSION

The Delirium Interview is a feasible reference method for large study cohorts evaluating delirium assessment tools since experts could assess delirium with high accuracy without seeing the patient at the bedside.

Collaborative study for the establishment of Ph. Eur. Biological Reference Preparation for Human tetanus immunoglobulin batch 2

This publication describes the outcome of a project to develop a replacement European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) for Human tetanus immunoglobulin (TIg) as well as for the World Health Organization (WHO) International Standard (IS) for Tetanus Immunoglobulin, Human. Bulk TIg was kindly provided by a European manufacturer and was used to prepare the candidate standard. The candidate standard was freeze-dried and calibrated in an international collaborative study jointly co-ordinated by the Medicines & Healthcare products Regulatory Agency (MHRA) and the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe). The results of this study show that there was good agreement between laboratories for the potency estimates obtained for the candidate standard relative to the current WHO IS/Ph. Eur. BRP. The study also demonstrated that the candidate standard is suitable for use in Ph. Eur. assays for potency testing of TIg products and there was good agreement in the potency estimates obtained using the different assay methods included in the study. Accelerated degradation studies performed at the MHRA over a period of 4 years suggest that the freeze-dried candidate standard will be very stable. The candidate standard was established as Ph. Eur. BRP for Human tetanus immunoglobulin, batch 2 with an assigned potency of 45 IU/ampoule. The same preparation was also adopted by the WHO Expert Committee on Biological Standardization (ECBS) to serve as the WHO 2nd IS for Tetanus Immunoglobulin, Human (13/240).

Collaborative study for the establishment of replacement batches of Ph. Eur. Heparin Low-Molecular-Mass for Calibration CRS

An international collaborative study was run within the framework of the Biological Standardisation Programme (BSP) of the Council of Europe and the Commission of the European Union to establish replacement batches for European Pharmacopoeia (Ph. Eur.) Heparin Low-Molecular-Mass (LMM) for calibration Chemical Reference Substance batch 3 (CRS3) used for the characterisation of LMM heparins by high performance size-exclusion chromatography. Two candidate batches (A, cCRS4 and B, cCRS5) were filled using the same material as the existing official calibrants, adopted with either an assigned number-average molecular mass (Mna) or a broad standard table (BST). Fifteen laboratories evaluated the suitability of these candidate batches for use as calibrants with the pharmacopoeial dual refractive index/ultraviolet (RI/UV) detector calibration method, as well as with a modified mobile phase and the BST calibration method. Seven preparations of LMM heparin were tested. The results confirmed that the proposed batches are suitable for use with the same characteristic Mna as CRS3 and with the BST established for the World Health Organization (WHO) 2nd International Standard (IS). The BST calibration method gave comparable results to the RI/UV method, while showing better reproducibility, being easier to perform and requiring no calibrant with UV absorbance. The modified mobile phase had no impact on the calculated values while improving separation between the calibrant and salt peaks. The two candidate batches were adopted as Ph. Eur. Heparin LMM for calibration CRS batches 4 and 5, respectively, with the assigned Mna value of 3800 and a BST. In anticipation of the depletion of the calibrant required for use with the RI/UV method, and taking into account the unlikely procurement of a new lot of suitable starting material, it was recommended to include the BST method in Ph. Eur. monograph 0828, Heparins, low-molecular-mass. In order to improve peak separation, it was also recommended to include the use of ammonium acetate solution as mobile phase in the monograph, both for the Ph. Eur. RI/UV and the proposed BST calibration methods. Further to this study, Ph. Eur. monograph 0828 was revised to replace the RI/UV method by the BST method. This contributed to the harmonisation of methods across regions, thereby facilitating a concerted global action for the development and establishment of the next batches of calibrants for the quality control of LMM heparins.

Correcting Diagnostic Test Sensitivity and Specificity for Patient Misclassifications Resulting from Use of an Imperfect Reference Standard

Investigational diagnostic tests are validated by using a reference standard (RS). If the RS is imperfect (i.e., it has sensitivity [Se] and/or specificity [Sp] < 1), incorrect values for the investigational test’s Se and Sp may result because of patient misclassification by the RS. Formulas were derived to correct a test’s Se and Sp that were determined by using an imperfect RS. The following derived formulas correct for misclassification and give the true numbers of disease-positive [nDP] and disease-negative patients [nDN] from the apparent number of disease-positive and disease-negative patients (anDP and anDN), and the Se and Sp of the RS (SeR, SpR): nDP = (anDP × SpR + anDN × SpR − anDN)/JR; nDN = (anDP × SeR + anDN × SeR − anDP)/JR, where JR is Youden’s Index for the RS (JR = SeR + SpR − 1). The following derived formulas give the correct Se and Sp of an investigational test (SeI and SpI): SeI = (anTPI × SpR − nDP × SeR × SpR + nDP × JR + nDN × SpR2 − nDN × SpR − SpR × anTNI + anTNI)/(nDP × JR); SpI = (anTPI − anTPI × SeR + nDP × SeR2 − nDP × SeR − SeR × nDN × SpR + nDN × JR + SeR × anTNI)/(nDN × JR), where anTPI is the apparent number of true-positive test results, and anTNI is the apparent number of true-negative test results. The derived formulas correct for patient misclassification by an imperfect RS and give the correct values of a diagnostic test’s Se and Sp.

Methodological Recommendations for Studies on the Daily Life Implementation of Implantable Communication-Brain-Computer Interfaces for Individuals With Locked-in Syndrome

Implantable brain-computer interfaces (BCIs) promise to be a viable means to restore communication in individuals with locked-in syndrome (LIS). In 2016, we presented the world-first fully implantable BCI system that uses subdural electrocorticography electrodes to record brain signals and a subcutaneous amplifier to transmit the signals to the outside world, and that enabled an individual with LIS to communicate via a tablet computer by selecting icons in spelling software. For future clinical implementation of implantable communication-BCIs, however, much work is still needed, for example, to validate these systems in daily life settings with more participants, and to improve the speed of communication. We believe the design and execution of future studies on these and other topics may benefit from the experience we have gained. Therefore, based on relevant literature and our own experiences, we here provide an overview of procedures, as well as recommendations, for recruitment, screening, inclusion, imaging, hospital admission, implantation, training, and support of participants with LIS, for studies on daily life implementation of implantable communication-BCIs. With this article, we not only aim to inform the BCI community about important topics of concern, but also hope to contribute to improved methodological standardization of implantable BCI research.

Diagnostic Utility of Computed Tomography Perfusion in the Telestroke Setting

BACKGROUND

Definitive diagnosis of acute ischemic stroke is challenging, particularly in telestroke settings. Although the prognostic utility of CT perfusion (CTP) has been questioned, its diagnostic value remains under-appreciated, especially in cases without an easily visible intracranial occlusion. We assessed the diagnostic accuracy of routine CTP in the acute telestroke setting.

METHODS

Acute and follow-up data collected prospectively from consecutive suspected patients with stroke assessed by a state-wide telestroke service between March 2020 and August 2021 at 12 sites in Australia were analyzed. All patients in the final analysis had been assessed with multimodal CT, including CTP, which was post-processed with automated volumetric software. Diagnostic sensitivity and specificity were calculated for multimodal CT and each individual component (noncontrast CT [NCCT], CT angiogram [CTA], and CTP). Final diagnosis determined by consensus review of follow-up imaging and clinical data was used as the reference standard.

RESULTS

During the study period, complete multimodal CT examination was obtained in 831 patients, 457 of whom were diagnosed with stroke. Diagnostic sensitivity for ischemic stroke increased by 19.5 percentage points when CTP was included with NCCT and CTA compared with NCCT and CTA alone (73.1% positive with NCCT+CTA+CTP [95% CI, 68.8-77.1] versus 53.6% positive with NCCT+CTA alone [95% CI, 48.9-58.3], P<0.001). No difference was observed between specificities of NCCT+CTA and NCCT+CTA+CTP (98.7% [95% CI, 98.5-100] versus 98.7% [95% CI, 96.9-99.6], P=0.13). Multimodal CT, including CTP, demonstrated the highest negative predictive value (75.0% [95% CI, 72.1-77.7]). Patients with stroke not evident on CTP had small volume infarcts on follow-up (1.2 mL, interquartile range 0.5-2.7mL).

CONCLUSIONS

Acquisition of CTP as part of a telestroke imaging protocol permits definitive diagnosis of cerebral ischemia in 1 in 5 patients with normal NCCT and CTA.

Tuberculosis Diagnosis in HIV-Infected Children: Comparison of the 2012 and 2015 Clinical Case Definitions for Classification of Intrathoracic Tuberculosis Disease

BACKGROUND

There is no gold standard for tuberculosis diagnosis in children. Clinical Case Definitions for Classification of Intrathoracic Tuberculosis in Children were proposed by international experts in 2012 and updated in 2015. We aimed to compare the 2012 and 2015 Clinical Case Definitions in HIV-infected children with suspected tuberculosis.

METHODS

We enrolled HIV-infected children with suspected tuberculosis in Burkina Faso, Cambodia, Cameroon, and Vietnam (ANRS [Agence Nationale de Recherches sur le SIDA et les hépatites virales] 12229 PAANTHER [Pediatric Asian African Network for Tuberculosis and HIV Research] 01 Study). We classified children using the 2012 and 2015 Case Definitions considering as tuberculosis cases those with confirmed tuberculosis and those with probable and unconfirmed tuberculosis in the 2012 and the 2015 classifications, respectively. We assessed agreement between both classifications.

RESULTS

Of 438 children enrolled, 197 (45.0%) children were classified as tuberculosis (45 confirmed, 152 probable) using the 2012 Case Definition and 251 (57.3%) were classified as tuberculosis (55 confirmed, 196 unconfirmed) using the 2015 classification. Inter-classification agreement for tuberculosis diagnosis was 364/438, 83.1%, with a kappa statistic of 0.667 (95% confidence interval 0.598-0.736). Of 152 children with probable tuberculosis (2012), 142 (93.4%) were considered as tuberculosis by the 2015 version and 10 (6.6%) as unlikely tuberculosis including 9 with spontaneous clinical improvement. Of 132 possible tuberculosis (2012), 58 (43.9%) were reclassified as tuberculosis (2015).

CONCLUSIONS

Agreement between the 2 versions of the Case Definition was substantial but more children were considered as tuberculosis using the 2015 version. Spontaneous symptom resolution reinforces both confidence in the "unlikely" category as being children without tuberculosis and the importance of the clinician's treatment decision in the study.

Predicting Frailty and Geriatric Interventions in Older Cancer Patients: Performance of Two Screening Tools for Seven Frailty Definitions-ELCAPA Cohort

Screening tools have been developed to identify patients warranting a complete geriatric assessment (GA). However, GA lacks standardization and does not capture important aspects of geriatric oncology practice. We measured and compared the diagnostic performance of screening tools G8 and modified G8 according to multiple clinically relevant reference standards. We included 1136 cancer patients ≥ 70 years old referred for GA (ELCAPA cohort; median age, 80 years; males, 52%; main locations: digestive (36.3%), breast (16%), and urinary tract (14.8%); metastases, 43.5%). Area under the receiver operating characteristic curve (AUROC) estimates were compared between both tools against: (1) the detection of ≥1 or (2) ≥2 GA impairments, (3) the prescription of ≥1 geriatric intervention and the identification of an unfit profile according to (4) a latent class typology, expert-based classifications from (5) Balducci, (6) the International Society of Geriatric Oncology task force (SIOG), or using (7) a GA frailty index according to the Rockwood accumulation of deficits principle. AUROC values were ≥0.80 for both tools under all tested definitions. They were statistically significantly higher for the modified G8 for six reference standards: ≥1 GA impairment (0.93 vs. 0.89), ≥2 GA impairments (0.90 vs. 0.87), ≥1 geriatric intervention (0.85 vs. 0.81), unfit according to Balducci (0.86 vs. 0.80) and SIOG classifications (0.88 vs. 0.83), and according to the GA frailty index (0.86 vs. 0.84). Our findings demonstrate the robustness of both screening tools against different reference standards, with evidence of better diagnostic performance of the modified G8.

Validation of the Computerized Pediatric Triage Tool, pediaTRI, in the Pediatric Emergency Department of Lenval Children's Hospital in Nice: A Cross-Sectional Observational Study

INTRODUCTION

A reliable pediatric triage tool is essential for nurses working in pediatric emergency departments to quickly identify children requiring priority care (high-level emergencies) and those who can wait (low-level emergencies). In the absence of a gold standard in France, the objective of our study was to validate our 5-level pediatric triage tool -pediaTRI- against the reference tool: the Pediatric Early Warning Score (PEWS) System.

MATERIALS AND METHODS

We prospectively included 100,506 children who visited the Pediatric Emergency Department at Lenval Children's Hospital (Nice, France) in 2016 and 2017. The performance of pediaTRI to identify high-level emergencies (severity levels 1 and 2) was evaluated in comparison with a PEWS ≥ 4/9. Data from 2018-19 was used as an independent validation cohort.

RESULTS

pediaTRI agreed with the PEWS score for 84,896 of the patients (84.5%): 15.0% (14.8-15.2) of the patients were over-triaged and 0.5% (0.5-0.6) under-triaged compared with the PEWS score. pediaTRI had a sensitivity of 76.4% (74.6-78.2), a specificity of 84.7% (84.4-84.9), and positive and negative likelihood ratios of 5.0 (4.8-5.1) and 0.3 (0.3-0.3), respectively, for the identification of high-level emergencies. However, the positive likelihood ratios were lower for patients presenting with a medical complaint [4.1 (4.0-4.2) v 10.4 (7.9-13.7 for trauma), and for younger children [1.2 (1.1-1.2) from 0 to 28 days, and 1.9 (1.8-2.0) from 28 days to 3 months].

CONCLUSION

pediaTRI has a moderate to good validity to triage children in a Pediatric Emergency Department with a tendency to over-triage compared with the PEWS system. Its validity is lower for younger children and for children consulting for a medical complaint.

A Pathologist-Annotated Dataset for Validating Artificial Intelligence: A Project Description and Pilot Study

Purpose:

Validating artificial intelligence algorithms for clinical use in medical images is a challenging endeavor due to a lack of standard reference data (ground truth). This topic typically occupies a small portion of the discussion in research papers since most of the efforts are focused on developing novel algorithms. In this work, we present a collaboration to create a validation dataset of pathologist annotations for algorithms that process whole slide images. We focus on data collection and evaluation of algorithm performance in the context of estimating the density of stromal tumor-infiltrating lymphocytes (sTILs) in breast cancer.

Methods:

We digitized 64 glass slides of hematoxylin- and eosin-stained invasive ductal carcinoma core biopsies prepared at a single clinical site. A collaborating pathologist selected 10 regions of interest (ROIs) per slide for evaluation. We created training materials and workflows to crowdsource pathologist image annotations on two modes: an optical microscope and two digital platforms. The microscope platform allows the same ROIs to be evaluated in both modes. The workflows collect the ROI type, a decision on whether the ROI is appropriate for estimating the density of sTILs, and if appropriate, the sTIL density value for that ROI.

Results:

In total, 19 pathologists made 1645 ROI evaluations during a data collection event and the following 2 weeks. The pilot study yielded an abundant number of cases with nominal sTIL infiltration. Furthermore, we found that the sTIL densities are correlated within a case, and there is notable pathologist variability. Consequently, we outline plans to improve our ROI and case sampling methods. We also outline statistical methods to account for ROI correlations within a case and pathologist variability when validating an algorithm.

Conclusion:

We have built workflows for efficient data collection and tested them in a pilot study. As we prepare for pivotal studies, we will investigate methods to use the dataset as an external validation tool for algorithms. We will also consider what it will take for the dataset to be fit for a regulatory purpose: study size, patient population, and pathologist training and qualifications. To this end, we will elicit feedback from the Food and Drug Administration via the Medical Device Development Tool program and from the broader digital pathology and AI community. Ultimately, we intend to share the dataset, statistical methods, and lessons learned.

Injured patients who would benefit from expedited major trauma centre care: a consensus-based definition for the United Kingdom

INTRODUCTION

Despite the importance of treating the 'right patient in the right place at the right time', there is no gold standard for defining which patients should receive expedited major trauma centre (MTC) care. This study aimed to define a reference standard applicable to the United Kingdom (UK) National Health Service major trauma networks.

METHODS

A one-day facilitated roundtable expert consensus meeting was conducted at the University of Sheffield, UK, in September 2019. An expert panel of 17 clinicians was purposively sampled, representing all specialities relevant to major trauma management. A consultation process was subsequently held using focus groups with Public and Patient Involvement (PPI) representatives to review and confirm the proposed reference standard.

RESULTS

Four reference standard domains were identified, comprising: need for critical interventions; presence of significant individual anatomical injuries; burden of multiple minor injuries; and important patient attributes. Specific criteria were defined for each domain. PPI consultation confirmed all aspects of the reference standard. A coding algorithm to allow operationalisation in Trauma Audit and Research Network data was also formulated, allowing classification of any case submitted to their database for future research.

CONCLUSIONS

This reference standard defines which patients would benefit from expedited MTC care. It could be used as the target for future pre-hospital injury triage tools, for setting best practice tariffs for trauma care reimbursement and to evaluate trauma network performance. Future research is recommended to compare patient characteristics, management and outcomes of the proposed definition with previously established reference standards.

Assessing the Performance of Clinical Natural Language Processing Systems: Development of an Evaluation Methodology

Background

Clinical natural language processing (cNLP) systems are of crucial importance due to their increasing capability in extracting clinically important information from free text contained in electronic health records (EHRs). The conversion of a nonstructured representation of a patient’s clinical history into a structured format enables medical doctors to generate clinical knowledge at a level that was not possible before. Finally, the interpretation of the insights gained provided by cNLP systems has a great potential in driving decisions about clinical practice. However, carrying out robust evaluations of those cNLP systems is a complex task that is hindered by a lack of standard guidance on how to systematically approach them.

Objective

Our objective was to offer natural language processing (NLP) experts a methodology for the evaluation of cNLP systems to assist them in carrying out this task. By following the proposed phases, the robustness and representativeness of the performance metrics of their own cNLP systems can be assured.

Methods

The proposed evaluation methodology comprised five phases: (1) the definition of the target population, (2) the statistical document collection, (3) the design of the annotation guidelines and annotation project, (4) the external annotations, and (5) the cNLP system performance evaluation. We presented the application of all phases to evaluate the performance of a cNLP system called “EHRead Technology” (developed by Savana, an international medical company), applied in a study on patients with asthma. As part of the evaluation methodology, we introduced the Sample Size Calculator for Evaluations (SLiCE), a software tool that calculates the number of documents needed to achieve a statistically useful and resourceful gold standard.

Results

The application of the proposed evaluation methodology on a real use-case study of patients with asthma revealed the benefit of the different phases for cNLP system evaluations. By using SLiCE to adjust the number of documents needed, a meaningful and resourceful gold standard was created. In the presented use-case, using as little as 519 EHRs, it was possible to evaluate the performance of the cNLP system and obtain performance metrics for the primary variable within the expected CIs.

Conclusions

We showed that our evaluation methodology can offer guidance to NLP experts on how to approach the evaluation of their cNLP systems. By following the five phases, NLP experts can assure the robustness of their evaluation and avoid unnecessary investment of human and financial resources. Besides the theoretical guidance, we offer SLiCE as an easy-to-use, open-source Python library.

Identifying and Avoiding Risk of Bias in Caries Diagnostic Studies

Caries diagnostic studies differ with respect to their design, included patients/tooth samples, use of diagnostic and reference methods, calibration, blinding and data reporting. Such heterogeneity makes comparisons between studies difficult and could represent a substantial risk of bias (RoB) when it is not identified. Therefore, the present report aims to describe the development and background of a RoB assessment tool for caries diagnostic studies. The expert group developed and agreed to use a RoB assessment tool during three workshops. Here, existing instruments (e.g., QUADAS 2 and the Joanna Briggs Institute Reviewers' Manual) influenced the hierarchy and phrasing of the signalling questions that were adapted to the specific dental purpose. The tailored RoB assessment tool that was created consists of 16 signalling questions that are organized in four domains. This tool considers the selection/spectrum bias (1), the bias of the index (2) and reference tests (3), and the bias of the study flow and data analysis (4) and can be downloaded from the journal website. This paper explores possible sources of heterogeneity and bias in caries diagnostic studies and summarizes the relevant methodological aspects.

Development and Validation of Measurement Traceability for In Situ Immunoassays

BACKGROUND

Immunoassays for protein analytes measured in situ support a $2 billion laboratory testing industry that suffers from significant interlaboratory disparities, affecting patient treatment. The root cause is that immunohistochemical testing lacks the generally accepted tools for analytic standardization, including reference standards and traceable units of measure. Until now, the creation of these tools has represented an insoluble technical hurdle.

METHODS

We address the need with a new concept in metrology-that is, linked traceability. Rather than calculating analyte concentration directly, which has proven too variable, we calculate concentration by measuring an attached fluorescein, traceable to NIST Standard Reference Material 1934, a fluorescein standard.

RESULTS

For validation, newly developed estrogen receptor (ER) calibrators were deployed in tandem with an array of 80 breast cancer tissue sections in a national external quality assessment program. Laboratory performance was assessed using both the ER standards and the tissue array. Similar to previous studies, the tissue array revealed substantial discrepancies in ER test results among the participating laboratories. The new ER calibrators revealed a broad range of analytic sensitivity, with the lower limits of detection ranging from 7310 to 74 790 molecules of ER. The data demonstrate, for the first time, that the variable test results correlate with analytic sensitivity, which can now be measured quantitatively.

CONCLUSIONS

The reference standard enables precise interlaboratory alignment of immunohistochemistry test sensitivity for measuring cellular proteins in situ. The introduction of a reference standard and traceable units of measure for protein expression marks an important milestone.

COVID-19 Vaccines: Current Understanding on Immunogenicity, Safety, and Further Considerations

The world has entered the second wave of the COVID-19 pandemic, and its intensity is significantly higher than that of the first wave of early 2020. Many countries or regions have been forced to start the second round of lockdowns. To respond rapidly to this global pandemic, dozens of COVID-19 vaccine candidates have been developed and many are undergoing clinical testing. Evaluating and defining effective vaccine candidates for human use is crucial for prioritizing vaccination programs against COVID-19. In this review, we have summarized and analyzed the efficacy, immunogenicity and safety data from clinical reports on different COVID-19 vaccines. We discuss the various guidelines laid out for the development of vaccines and the importance of biological standards for comparing the performance of vaccines. Lastly, we highlight the key remaining challenges, possible strategies for addressing them and the expected improvements in the next generation of COVID-19 vaccines.

Calibration of the Ph. Eur. human coagulation Factor VIII Concentrate BRP batch 6

The European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) for human coagulation Factor VIII (FVIII) Concentrate is used as working standard for potency determination of human coagulation FVIII preparations by chromogenic assay. BRP batch 5 was established in 2015 and its stocks were running low. Therefore, the European Directorate for the Quality of Medicines & HealthCare (EDQM) initiated a project (BSP156) for the calibration of a replacement batch. The potency of BRP batch 6 was assigned during an international collaborative study involving 16 laboratories worldwide, with reference to the WHO 8th International Standard (IS) and BRP batch 5. Participants were instructed to perform 3 independent FVIII potency assays following their own routine validated methods for the chromogenic assay, which is the assay prescribed by the Ph. Eur. As an outcome of the study, Ph. Eur. human coagulation FVIII Concentrate BRP batch 6 was assigned a consensus potency of 9.9 IU/ampoule for the chromogenic assay. The Ph. Eur. BRP batch 6 is a freeze-dried, plasma-derived concentrate. Based on accelerated degradation studies, the stability of the material is suitable for a reference preparation. The Ph. Eur. BRP batch 6 was adopted at the 167th session of the Ph. Eur. Commission in June 2020 and is available from the EDQM under product code H0920000.

Ultrasound imaging, a stethoscope for body composition assessment

Dysregulation of the human's energy balance, mediated by non-performing endocrine organs (liver, skeletal muscle and adipose tissue, above all), can be related to human metabolic disorders characterized by an impaired body composition (BC), such as obesity and sarcopenia. While it is possible to monitor the BC and its variations at different levels, the tissue-organ composition studies have been proven to provide the most clinically applicable information. Ultrasonography (US), a fast, non-invasive, low-cost and widely available technique, holds great potential in the study of BC, as it can directly measure muscles, organs, visceral and subcutaneous fat tissue in different sections of the abdomen and body, overcoming some limits of anthropometric evaluation and other imaging techniques. Purpose of this review article is to explore the technical aspects and the applied methods of US examination to assess the potential clinical role of this technique in the context of BC characterization, investigating four pivotal topics [abdominal fat compartments, subcutaneous adipose tissue (SAT), skeletal muscle, liver].

A curve similarity approach to parallelism testing in bioassay

Potency determination via bioassay is a relative measure that requires an evaluation of parallelism between the dose-response relationships of a reference standard and a sample material. Typical approaches for assessing parallelism include difference ([Formula: see text]-value) and equivalence tests. These traditional methods rely on a statistical assessment of model parameters as opposed to direct evaluation of the similarity of the dose-response curves. We propose a simple curve similarity approach that tests the hypothesis that the sample material is a dilution or concentration of the reference standard. The test is achieved by quantifying and normalizing the total area between the two curves and provides a single composite measure of parallelism. Both a frequentist and a Bayesian approach to the test are provided. We show through a simulation study that the curve similarity approach overcomes the drawbacks of the traditional methods and is effective at detecting parallelism and non-parallelism for bioassays.

[Lancet Commission on Hypertension Group position statement on the global improvement of accuracy standards for devices that measure blood pressurePosicionamento do Grupo da Lancet Commission on Hypertension sobre a melhoria global dos padrões de acurácia para aparelhos que medem a pressão arterial]

The Lancet Commission on Hypertension identified that a key action to address the worldwide burden of high blood pressure (BP) was to improve the quality of BP measurements by using BP devices that have been validated for accuracy. Currently, there are over 3 000 commercially available BP devices, but many do not have published data on accuracy testing according to established scientific standards. This problem is enabled through weak or absent regulations that allow clearance of devices for commercial use without formal validation. In addition, new BP technologies have emerged (e.g. cuffless sensors) for which there is no scientific consensus regarding BP measurement accuracy standards. Altogether, these issues contribute to the widespread availability of clinic and home BP devices with limited or uncertain accuracy, leading to inappropriate hypertension diagnosis, management and drug treatment on a global scale. The most significant problems relating to the accuracy of BP devices can be resolved by the regulatory requirement for mandatory independent validation of BP devices according to the universally-accepted International Organization for Standardization Standard. This is a primary recommendation for which there is an urgent international need. Other key recommendations are development of validation standards specifically for new BP technologies and online lists of accurate devices that are accessible to consumers and health professionals. Recommendations are aligned with WHO policies on medical devices and universal healthcare. Adherence to recommendations would increase the global availability of accurate BP devices and result in better diagnosis and treatment of hypertension, thus decreasing the worldwide burden from high BP.

Lancet Commission on Hypertension group position statement on the global improvement of accuracy standards for devices that measure blood pressure

: The Lancet Commission on Hypertension identified that a key action to address the worldwide burden of high blood pressure (BP) was to improve the quality of BP measurements by using BP devices that have been validated for accuracy. Currently, there are over 3000 commercially available BP devices, but many do not have published data on accuracy testing according to established scientific standards. This problem is enabled through weak or absent regulations that allow clearance of devices for commercial use without formal validation. In addition, new BP technologies have emerged (e.g. cuffless sensors) for which there is no scientific consensus regarding BP measurement accuracy standards. Altogether, these issues contribute to the widespread availability of clinic and home BP devices with limited or uncertain accuracy, leading to inappropriate hypertension diagnosis, management and drug treatment on a global scale. The most significant problems relating to the accuracy of BP devices can be resolved by the regulatory requirement for mandatory independent validation of BP devices according to the universally-accepted International Organisation for Standardization Standard. This is a primary recommendation for which there is an urgent international need. Other key recommendations are development of validation standards specifically for new BP technologies and online lists of accurate devices that are accessible to consumers and health professionals. Recommendations are aligned with WHO policies on medical devices and universal healthcare. Adherence to recommendations would increase the global availability of accurate BP devices and result in better diagnosis and treatment of hypertension, thus decreasing the worldwide burden from high BP.

In Vitro Effects of Cyclic Dislodgement on Retentive Properties of Various Titanium-Based Dental Implant Overdentures Attachment System

The purpose of this study was to evaluate the change in the retentive forces of four different titanium-based implant attachment systems during the simulation of insert–removal cycles in an artificial oral environment. Five types of titanium-based dental implant attachment systems (Locator, Kerator, O-ring, EZ-Lock, and Magnetic) were studied (n = 10). The specimens underwent insert–removal cycles in artificial saliva, and the retentive force was measured following 0, 750, 1500, and 2250 cycles. Significant retention loss was observed in all attachment systems, except the magnetic attachments, upon completion of 2250 insertion and removal cycles, compared to the initial retentive force (p < 0.05). A comparison of the initial retentive forces revealed the highest value for Locator, followed by the Kerator, O-ring, EZ-Lock, and Magnetic attachments. Furthermore, Kerator demonstrated the highest retentive loss, followed by Locator, O-ring, EZ-Lock, and Magnetic attachments after 2250 cycles (p < 0.05). In addition, the Locator and Kerator systems revealed significant decrease in retentive forces at all measurement points (p < 0.05). The retention force according to the insert–removal cycles were significantly different according to the types of dental implant attachment systems.

The Impact of GE Lunar vs ICMR Database in Diagnosis of Osteoporosis among South Indian Subjects

OBJECTIVE

To study the effect of choosing ICMR reference values on the classification of bone mineral density in Indian patients.

DESIGN

Retrospective analysis of Dual Energy X-ray absorptiometry (DEXA) and clinical data.

PATIENTS

Totally, 316 patients aged more than 65 years attending a tertiary care hospital in South India who underwent DEXA scan were included in the study.

MEASUREMENTS

DEXA scan at femoral neck and lumbar spine.

RESULTS

A total of 316 patients were studied. The mean age was 61.98 ± 7.66 years. There were 46.84% females and 53.16% males. The average BMI was 26.37 ± 4.51. Of these patients, 46 had history of hip fracture (14.55%). The adoption of the ICMR normative data resulted in a significant increase in T scores in both the hip (+0.51, P < 0.05) and the spine (+1.64, P < 0.01). The adoption of ICMR normative values, resulted in reduction of osteoporosis prevalence from 26.58% to 5.06%.

CONCLUSIONS

There is a clinically significant reduction in diagnosis of osteoporosis with the adoption of ICMR reference standard. Clinicians should be recommended to use raw BMD values in gm/cm² in FRAX calculation and avoid the use of T scores, to avoid overestimation of fracture risk. If our results are replicated, the implications are enormous - Osteoporosis is currently being over diagnosed.

Extended Physicochemical Characterization of the Synthetic Anticoagulant Pentasaccharide Fondaparinux Sodium by Quantitative NMR and Single Crystal X-ray Analysis

Fondaparinux sodium is a synthetic pentasaccharide representing the high affinity antithrombin III binding site in heparin. It is the active pharmaceutical ingredient of the anticoagulant drug Arixtra^®. The single crystal X-ray structure of Fondaparinux sodium is reported, unequivocally confirming both structure and absolute configuration. The iduronic acid adopts a somewhat distorted chair conformation. Due to the presence of many sulfur atoms in the highly sulfated pentasaccharide, anomalous dispersion could be applied to determine the absolute configuration. A comparison with the conformation of Fondaparinux in solution, as well as complexed with proteins is presented. The content of the solution reference standard was determined by quantitative NMR using an internal standard both in 1999 and in 2016. A comparison of the results allows the conclusion that this method shows remarkable precision over time, instrumentation and analysts.

Validity of the Digital Inclinometer and iPhone When Measuring Thoracic Spine Rotation

CONTEXT

  Spinal axial rotation is required for many functional and sporting activities. Eighty percent of axial rotation occurs in the thoracic spine. Existing measures of thoracic spine rotation commonly involve laboratory equipment, use a seated position, and include lumbar motion. A simple performance-based outcome measure would allow clinicians to evaluate isolated thoracic spine rotation. Currently, no valid measure exists.

OBJECTIVE

  To explore the criterion and concurrent validity of a digital inclinometer (DI) and iPhone Clinometer app (iPhone) for measuring thoracic spine rotation using the heel-sit position.

DESIGN

  Controlled laboratory study.

SETTING

  University laboratory.

PATIENTS OR OTHER PARTICIPANTS

  A total of 23 asymptomatic healthy participants (14 men, 9 women; age = 25.82 ± 4.28 years, height = 170.26 ± 8.01 cm, mass = 67.50 ± 9.46 kg, body mass index = 23.26 ± 2.79) were recruited from a student population.

MAIN OUTCOME MEASURE(S)

  We took DI and iPhone measurements of thoracic spine rotation in the heel-sit position concurrently with dual-motion analysis (laboratory measure) and ultrasound imaging of the underlying bony tissue motion (reference standard). To determine the criterion and concurrent validity, we used the Pearson product moment correlation coefficient (r, 2 tailed) and Bland-Altman plots.

RESULTS

  The DI (r = 0.88, P < .001) and iPhone (r = 0.88, P < .001) demonstrated strong criterion validity. Both also had strong concurrent validity (r = 0.98, P < .001). Bland-Altman plots illustrated mean differences of 5.82° (95% confidence interval [CI] = 20.37°, -8.73°) and 4.94° (95% CI = 19.23°, -9.35°) between the DI and iPhone, respectively, and the reference standard and 0.87° (95% CI = 6.79°, -5.05°) between the DI and iPhone.

CONCLUSIONS

  The DI and iPhone provided valid measures of thoracic spine rotation in the heel-sit position. Both can be used in clinical practice to assess thoracic spine rotation, which may be valuable when evaluating thoracic dysfunction.

Calibration of the Ph. Eur. human coagulation Factor VIII concentrate BRP batch 5

The European Pharmacopoeia Biological Reference Preparation (Ph. Eur. BRP) for Factor VIII Concentrate batch 5 was established through a collaborative study involving 14 laboratories organised by the European Directorate for the Quality of Medicines & HealthCare (EDQM, Council of Europe) to be used as working standard for potency determination of human coagulation Factor VIII (FVIII) preparations. The potency of the BRP batch 5 was assigned with reference to the WHO 8^th International Standard (IS) for FVIII Concentrate and the BRP batch 4. Participants were instructed to perform 3 independent Factor VIII potency assays following their own routine validated methods by the chromogenic assay as it is the assay prescribed by the European Pharmacopoeia. This publication reports the results obtained during the study. The consensus potency, 9.9 IU/ampoule (n = 14) when assessed against both standards, with inter-laboratory geometric coefficients of variation (GCV) of 3.2 % and 1.9 % against the WHO 8^th IS and the BRP batch 4 respectively, was consistent with the expected value. The Ph. Eur. BRP batch 5 is a freeze-dried, plasma-derived concentrate. Based on accelerated degradation studies, the stability of the material is suitable as a reference preparation. The Ph. Eur. BRP batch 5 was adopted at the 151^st session of the European Pharmacopoeia Commission in March 2015 and is available from the EDQM.

Quantification of low levels of methionine oxidation in erythropoietin drug substance

A pharmacopoeial monograph under development for recombinant human erythropoietin (rhEPO) drug substance is likely to contain a specification limit for the proportion of the methionine-oxidised variant. Methionine oxidation has no effect on the folded structure and global thermodynamic stability of rhEPO but can decrease biological activity [1]. We describe here the development of a reference standard, a calibrated mixture of the native and oxidised tryptic peptides which contain methionine-54, and an optimised peptide mapping procedure to support this assay. The approach may be developed for analysis of drug product or generalised for other assays in which product-related impurities are quantified by peptide mapping.

Outcomes-based assessment of a new reference standard for delayed cerebral ischemia related to vasospasm in aneurysmal subarachnoid hemorrhage

RATIONALE AND OBJECTIVES

The purpose is to perform outcomes-based assessment of a new reference standard for delayed cerebral ischemia (DCI) related to vasospasm.

MATERIALS AND METHODS

Retrospective study was performed with consecutive aneurysmal subarachnoid hemorrhage (A-SAH) patients between January 2002 and May 2009. A new reference standard for DCI was applied to the study population incorporating clinical and imaging criteria. Diagnostic accuracy was determined by chart diagnosis. Outcome measures for assessment included: permanent neurologic deficits, infarction, functional disability, treatment, and discharge status. Medical record review was performed by two blinded observers. Chi-square test calculated statistical significance between DCI and no DCI groups.

RESULTS

A total of 137 patients were included; 59% (81/137) classified as DCI and 41% (56/137) as no DCI by the reference standard. Overall accuracy is 96% (95% confidence interval 92-99) with 100% sensitivity, 92% specificity, 94% positive and 100% negative predictive values. Patients classified as DCI had 40% (32/81) permanent neurologic deficits and 57% (46/81) infarction compared to 0% (0/56) classified as no DCI. DCI patients had 33% (27/81) functional disability compared to 13% (7/56) classified as no DCI. Ninety-four percent (76/81) DCI patients received treatment compared to 0% (0/56) classified as no DCI. DCI group had 46% (37/81) discharged to rehabilitation facilities and 11% (9/81) mortality compared to 25% (14/56) and 2% (1/56), respectively, in no DCI group. There are statistically significant differences (P < .0001) between DCI and no DCI groups for all outcome measures.

CONCLUSION

This new reference standard has high diagnostic accuracy for DCI related to vasospasm. The outcomes-based assessment further supports its accuracy in correctly classifying A-SAH patients.

Estimating a reference standard segmentation with spatially varying performance parameters: local MAP STAPLE

We present a new algorithm, called local MAP STAPLE, to estimate from a set of multi-label segmentations both a reference standard segmentation and spatially varying performance parameters. It is based on a sliding window technique to estimate the segmentation and the segmentation performance parameters for each input segmentation. In order to allow for optimal fusion from the small amount of data in each local region, and to account for the possibility of labels not being observed in a local region of some (or all) input segmentations, we introduce prior probabilities for the local performance parameters through a new maximum a posteriori formulation of STAPLE. Further, we propose an expression to compute confidence intervals in the estimated local performance parameters. We carried out several experiments with local MAP STAPLE to characterize its performance and value for local segmentation evaluation. First, with simulated segmentations with known reference standard segmentation and spatially varying performance, we show that local MAP STAPLE performs better than both STAPLE and majority voting. Then we present evaluations with data sets from clinical applications. These experiments demonstrate that spatial adaptivity in segmentation performance is an important property to capture. We compared the local MAP STAPLE segmentations to STAPLE, and to previously published fusion techniques and demonstrate the superiority of local MAP STAPLE over other state-of-the-art algorithms.

The Research Diagnostic Criteria for Temporomandibular Disorders. V: methods used to establish and validate revised Axis I diagnostic algorithms

AIMS

To derive reliable and valid revised Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I diagnostic algorithms for clinical TMD diagnoses.

METHODS

The multisite RDC/TMD Validation Project's dataset (614 TMD community and clinic cases, and 91 controls) was used to derive revised algorithms for Axis I TMD diagnoses. Validity of diagnostic algorithms was assessed relative to reference standards, the latter based on consensus diagnoses rendered by two TMD experts using criterion examination data, including temporomandibular joint imaging. Cutoff points for target validity were sensitivity > or = 0.70 and specificity > or = 0.95. Reliability of revised algorithms was assessed in 27 study participants.

RESULTS

Revised algorithm sensitivity and specificity exceeded the target levels for myofascial pain (0.82, 0.99, respectively) and myofascial pain with limited opening (0.93, 0.97). Combining diagnoses for any myofascial pain showed sensitivity of 0.91 and specificity of 1.00. For joint pain, target sensitivity and specificity were observed (0.92, 0.96) when arthralgia and osteoarthritis were combined as "any joint pain." Disc displacement without reduction with limited opening demonstrated target sensitivity and specificity (0.80, 0.97). For the other disc displacement diagnoses, osteoarthritis and osteoarthrosis, sensitivity was below target (0.35 to 0.53), and specificity ranged from 0.80 to meeting target. Kappa for revised algorithm diagnostic reliability was > or =0.63.

CONCLUSION

Revised RDC/TMD Axis I TMD diagnostic algorithms are recommended for myofascial pain and joint pain as reliable and valid. However, revised clinical criteria alone, without recourse to imaging, are inadequate for valid diagnosis of two of the three disc displacements as well as osteoarthritis and osteoarthrosis.

The Research Diagnostic Criteria for Temporomandibular Disorders. I: overview and methodology for assessment of validity

AIMS

The purpose of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Validation Project was to assess the diagnostic validity of this examination protocol. The aim of this article is to provide an overview of the project's methodology, descriptive statistics, and data for the study participant sample. This article also details the development of reliable methods to establish the reference standards for assessing criterion validity of the Axis I RDC/TMD diagnoses.

METHODS

The Axis I reference standards were based on the consensus of two criterion examiners independently performing a comprehensive history, clinical examination, and evaluation of imaging. Intersite reliability was assessed annually for criterion examiners and radiologists. Criterion examination reliability was also assessed within study sites.

RESULTS

Study participant demographics were comparable to those of participants in previous studies using the RDC/TMD. Diagnostic agreement of the criterion examiners with each other and with the consensus-based reference standards was excellent with all kappas > or = 0.81, except for osteoarthrosis (moderate agreement, k = 0.53). Intrasite criterion examiner agreement with reference standards was excellent (k > or = 0.95). Intersite reliability of the radiologists for detecting computed tomography-disclosed osteoarthrosis and magnetic resonance imaging-disclosed disc displacement was good to excellent (k = 0.71 and 0.84, respectively).

CONCLUSION

The Validation Project study population was appropriate for assessing the reliability and validity of the RDC/TMD Axis I and II. The reference standards used to assess the validity of Axis I TMD were based on reliable and clinically credible methods.

The Research Diagnostic Criteria for Temporomandibular Disorders. III: validity of Axis I diagnoses

AIMS

To estimate the criterion validity of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I TMD diagnoses.

METHODS

A combined total of 614 TMD community and clinic cases and 91 controls were examined at three study sites. RDC/TMD Axis I diagnoses were algorithmically derived from an examination performed by calibrated dental hygienists. Reference standards ("gold standards") were established by means of consensus diagnoses rendered by two TMD experts using all available clinical data, including imaging findings. Validity of the RDC/TMD Axis I TMD diagnoses was estimated relative to the reference-standard diagnoses (gold standard diagnoses). Target sensitivity and specificity were set a priori at greater than or equal to 0.70 and greater than or equal to 0.95, respectively.

RESULTS

Target sensitivity and specificity were not observed for any of the eight RDC/TMD diagnoses. The highest validity was achieved for Group Ia myofascial pain (sensitivity 0.65, specificity 0.92) and Group Ib myofascial pain with limited opening (sensitivity 0.79, specificity 0.92). Target sensitivity and specificity were observed only when both Group I diagnoses were combined (0.87 and 0.98, respectively). For Group II (disc displacements) and Group III (arthralgia, arthritis, arthrosis) diagnoses, all estimates for sensitivity were below target (0.03 to 0.53), and specificity ranged from below to on target (0.86 to 0.99).

CONCLUSION

The RDC/TMD Axis I TMD diagnoses did not reach the targets set at sensitivity of > or = 0.70 and specificity of > or = 0.95. Target validity was obtained only for myofascial pain without differentiation between normal and limited opening. Revision of the current Axis I TMD diagnostic algorithms is warranted to improve their validity.

Effect of change of reference standard to NHANES III on interpretation of spirometric 'abnormality'

The American Thoracic Society has recently recommended the use of NHANES III spirometric reference standard in the United States. The objective of this study was to better quantify the well-known 'problem' of the change in interpretation of spirometry, as a consequence of the change from the other commonly used reference standards (Morris, Kory, Crapo, Knudson 1976, and Knudson 1983) to NHANES III. This is a cross-sectional study of spirometries of 1,106 non-Hispanic Caucasian American adults, including 234 subjects with obstructive and 228 subjects with restrictive spirometric 'abnormalities'. A weighted Kappa statistic was used to evaluate the level of agreement between NHANES III and other commonly used reference standards. The level of agreement in assessing the presence of an 'abnormality' was poor to moderate-values of Kappa statistic ranged from 0.13 to 0.46. There was however, good to very good level of agreement in assessing the severity of the 'abnormality'-values of Kappa statistic ranged from 0.61 to 0.91. This study better quantifies the well-known differences in the interpretation of spirometric 'abnormalities' as a consequence of the recommended change of reference standard to NHANES III, which in turn may cause confusion among patients and their treating physicians.

Absolute Isotopic Abundance and the Atomic Weight of a Reference Sample of Thallium

The accepted atomic weight of thallium has remained at a value of 204.37 ± 0.03 since 1962. At this level of uncertainty, however, the atomic weight becomes a limiting factor to high accuracy analysis. The new mass spectrometric determination of the atomic weight of thallium has been completed. A high precision assay technique was developed so that accurately known quantities of the 203Tl and 205Tl separated isotopes could be mixed to produce standards for calibration of the mass spectrometer. This assay technique involved the gravimetric determination of 99.3 percent of the0020thallium as Tl2CrO4. The soluble thallium was then aliquoted and determined by isotope dilution mass spectrometry. Before making up the final solutions from which the assay and calibration samples would be withdrawn, the separated isotopes were purified by solvent extraction and electrodeposition. A tungsten filament surface ionization technique was developed for the determination of precise isotopic abundance measurements for thallium. This technique allowed isotopic analysis of the separated isotopes, calibration standards, and a natural thallium reference standard with precisions of better than 0.1 percent. The 205Tl/2Tl absolute isotopic abundance ratio of the reference sample was found to be 2.38714 ± 0.00101, yielding an atomic weight of 204.38333 + 0.00018.

Absolute Isotopic Abundance Ratios and the Atomic Weight of a Reference Sample of Potassium

Solid sample, thermal ionization, mass spectrometry has been used to obtain absolute values for the isotopic abundance ratios of a reference sample of potassium. Standards of known isotopic composition, prepared by gravimetrically mixing nearly isotopically and chemically pure separated isotopes of, 39K and 41K, were used for calibration. The absolute isotopic abundance ratios are : 39K/41K = 13.8566 ± 0.0063 and 40K/41K = 0.0017343 ± 0.0000061 which yield atom percent compositions of 39K=93.2581 ± 0.0029. 40K = 0.01167 ± 0.00004, and 41K = 6.7302 ± 0.0029. The calculated atomic weight for potassium is 39.098304 ± 0.000058. The indicated uncertainties are overall limits of error which are the sum of the uncertainty components for ratio determinations and the components covering the effects of known sources of possible systematic error.