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PubMed2006

An assessment of inter-rater agreement of the literature filtering process in the development of evidence-based dietary guidelines.

OBJECTIVE: To determine whether the literature filtering process, a vital initial component of a systematic literature review, could be successfully completed by nutrition professionals or non-professionals. DESIGN: Using a diet-disease relationship as the guideline topic, inter-rater agreement for the title and abstract filtering processes between and among professionals and non-professionals was assessed and compared with an expert reference standard. Predetermined eligibility criteria were applied by all raters to 185 titles and 90 abstracts. Filtering decisions were initially made independently and then revised after a within-pair consensus meeting. SUBJECTS: The raters were six dietitians (RD) and six nutrition graduate students (Grad). To assess inter-rater agreement (reliability), each group was divided into three pairs. RESULTS: Weighted and unweighted kappa statistics and percentage agreement were calculated to determine the inter-rater agreement within pairs. Sensitivity and specificity estimates were determined by comparing responses with those of an expert reference standard. Overall, Grad pairs demonstrated greater inter-rater agreement than RD pairs for title filtering (P<0.05); no differences were observed for abstract filtering. Compared with the expert reference standard, every rater and pair had false-negative responses for both title and abstract filtering. CONCLUSIONS: After consensus meetings, both RDs and Grads were comparable in their agreement on title and abstract filtering, although important differences remained compared with the expert reference standard. This study provides preliminary findings on the value of utilising a non-expert pair in developing guidelines, and suggests that the literature filtering process is complex and quite subjective.

Adult↗

PubMed1988

Standardization by reference methods: a German viewpoint.

The problems of applying optimized as well as standardized methods to the determination of enzyme activities in modern clinical laboratories are described. The failure of the so-called 'New Concept of Reference Method Values' in the quality assessment of enzyme assays is evidenced, and the advantages of standardized methods rather than only standard materials is demonstrated. Finally, the great similarities among European national recommended methods for enzyme assay is emphasized by a comparison of results obtained in estimating 5 enzymes.

Enzymes↗

PubMed1988

Quantitative selected ion monitoring processing system: software and hardware for the automated collection and analysis of selected ion monitoring data acquired for use in pharmacokinetic studies.

The Quantitative Selected Ion Monitoring Processing System (QSIMPS) is a collection of software and hardware which was designed with the capacity to analyze 30,600 samples per year in support of pharmacokinetic studies. On a per sample basis, QSIMPS was designed to inject a sample into the GC, control the GC divert valve, collect selected ion monitoring data, identify the peaks for the drug and one metabolite and each compound's reference standard, fit the peaks to a relevant chromatographic model, calculate chromatographic features of merit, calculate the peak heights and ratio of the drug and its reference standard and the metabolite and its reference standard, and, using calibration data, convert the ratio to an amount of drug. On a per tray (batch) basis, QSIMPS was designed to fit all the peak height ratios from the calibration standards to either a linear equation, or a generalized nonlinear isotope dilution equation, report a statistical analysis of the fit, and, using aliquot factors, convert the measured amount of drug into concentrations. On a per project basis, QSIMPS prints reports summarizing statistical data on the calibration standards and the quality assurance samples, and prints reports presenting the concentration data as a function of, for examples, subject, drug treatment, time postdose, etc., along with other ancillary data such as subject sex, weight, species, etc. In addition, QSIMPS can fit the concentration data to a number of common pharmacokinetic model-derived equations, and report the resulting pharmacokinetic parameters along with a statistical comparison of the parameters.

Chromatography, Gas↗

PubMed2006

Is pain ever "normal"?

This article analyzes the Pain Terminology adopted by the International Association for the Study of Pain (IASP), noting that most of their pain categories are defined in terms of a reference standard of "normal" pain. Given the lack of any officially adopted operational definition of the word "normal," we argue that the use of this word expresses and maintains a paradigm that drives many clinicians' reasoning about their patients' pain. We offer evidence that this uninterrogated paradigm is being tacitly used to differentiate legitimate pain reports from malingering and drug seeking. We consider this unsubstantiated "folk" sense of "normal" in light of evidence-based, rationalized prototypes based on statistical analysis of empirical evidence. We conclude that evidence for consistency in the experience and expression of pain and for clinician accuracy in evaluating the veracity of that pain is lacking; therefore, the logical preconditions needed for a rationalized, evidence-based prototype of "normal" pain have yet to be met. We conclude that the use of "normal" as a reference standard leads to ineffective and inhumane management of patient pain and to the danger that third parties, such as insurance companies and drug enforcement agencies, will use this unsubstantiated reference standard to arbitrarily limit pain therapy options. The authors recommend that the word "normal" be expunged from the International Association for the Study of Pain, Pain Terminology.

Clinical Trials as Topic↗

PubMed2003

Birth characteristics and growth pattern in children with congenital cytomegalovirus infection.

Birth characteristics and growth pattern in 76 children with congenital cytomegalovirus (CMV) infection were compared to Swedish reference data. Infection classification was based on maternal sera during pregnancy. In 31 children the infection was primary and 31 children had reactivated (recurrent or secondary) congenital CMV infection. Infection type could not be determined in 14 children. Transient neonatal symptoms were apparent in 22 children and eight children had classical neurological CMV sequelae. Heterogeneous neurological disorders were found in 13 children. No significant differences in height, weight, and growth were found. The median follow-up time was 10 years. From 4 years old children with congenital CMV infection were taller than the reference standard. At 1 and 2 years, those children with primary congenital CMV infection were borderline shorter than reference standard, and from 4 years children with reactivated CMV infection were taller than the reference standard. In conclusion, no evidence was found verifying that congenital CMV infection causes short stature.

Birth Weight↗

PubMed2002

Simultaneous analysis for multiple heavy metals in contaminated biological samples.

In the present study, the conditions of analysis by inductively coupled plasma-atomic emission spectrometry (ICP-AES) were investigated. Twenty-six elements (Mg: 25 ppm; Sc: 10 ppm; Ti: 50 ppm; others: 100 ppm) were used as the elements interfering with selected 24 wavelengths. Consequently, the background values in 19 elements were subjected to some influences. However, all of these effects disappeared at low concentrations--less than 1 ppm of interfering elements. Next, the values from the ordinary calibration method were compared with those from the standard addition method using several biological samples. There was a discrepancy in the results obtained from both methods because of the sample, and three patterns were observed. However, no discrepancy was observed in the values for the standard reference materials using both methods. There was no significant difference between the certified values of the standard reference materials and the obtained ones by ICP. Therefore, the analytical wavelengths and the methods in the present study were suggested to be useful for ICP-AES analysis for environmental and/or biological samples.

Calibration↗

PubMed2003

Content validity of manual spinal palpatory exams - A systematic review.

BACKGROUND: Many health care professionals use spinal palpatory exams as a primary and well-accepted part of the evaluation of spinal pathology. However, few studies have explored the validity of spinal palpatory exams. To evaluate the status of the current scientific evidence, we conducted a systematic review to assess the content validity of spinal palpatory tests used to identify spinal neuro-musculoskeletal dysfunction. METHODS: Review of eleven databases and a hand search of peer-reviewed literature, published between 1965-2002, was undertaken. Two blinded reviewers abstracted pertinent data from the retrieved papers, using a specially developed quality-scoring instrument. Five papers met the inclusion/exclusion criteria. RESULTS: Three of the five papers included in the review explored the content validity of motion tests. Two of these papers focused on identifying the level of fixation (decreased mobility) and one focused on range of motion. All three studies used a mechanical model as a reference standard. Two of the five papers included in the review explored the validity of pain assessment using the visual analogue scale or the subjects' own report as reference standards. Overall the sensitivity of studies looking at range of motion tests and pain varied greatly. Poor sensitivity was reported for range of motion studies regardless of the examiner's experience. A slightly better sensitivity (82%) was reported in one study that examined cervical pain. CONCLUSIONS: The lack of acceptable reference standards may have contributed to the weak sensitivity findings. Given the importance of spinal palpatory tests as part of the spinal evaluation and treatment plan, effort is required by all involved disciplines to create well-designed and implemented studies in this area.

Adult↗

PubMed2001

Evaluation of delirium in critically ill patients: validation of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU).

OBJECTIVE: To develop and validate an instrument for use in the intensive care unit to accurately diagnose delirium in critically ill patients who are often nonverbal because of mechanical ventilation. DESIGN: Prospective cohort study. SETTING: The adult medical and coronary intensive care units of a tertiary care, university-based medical center. PATIENTS: Thirty-eight patients admitted to the intensive care units. MEASUREMENTS AND MAIN RESULTS: We designed and tested a modified version of the Confusion Assessment Method for use in intensive care unit patients and called it the CAM-ICU. Daily ratings from intensive care unit admission to hospital discharge by two study nurses and an intensivist who used the CAM-ICU were compared against the reference standard, a delirium expert who used delirium criteria from the Diagnostic and Statistical Manual of Mental Disorders (fourth edition). A total of 293 daily, paired evaluations were completed, with reference standard diagnoses of delirium in 42% and coma in 27% of all observations. To include only interactive patient evaluations and avoid repeat-observer bias for patients studied on multiple days, we used only the first-alert or lethargic comparison evaluation in each patient. Thirty-three of 38 patients (87%) developed delirium during their intensive care unit stay, mean duration of 4.2 +/- 1.7 days. Excluding evaluations of comatose patients because of lack of characteristic delirium features, the two critical care study nurses and intensivist demonstrated high interrater reliability for their CAM-ICU ratings with kappa statistics of 0.84, 0.79, and 0.95, respectively (p <.001). The two nurses' and intensivist's sensitivities when using the CAM-ICU compared with the reference standard were 95%, 96%, and 100%, respectively, whereas their specificities were 93%, 93%, and 89%, respectively. CONCLUSIONS: The CAM-ICU demonstrated excellent reliability and validity when used by nurses and physicians to identify delirium in intensive care unit patients. The CAM-ICU may be a useful instrument for both clinical and research purposes to monitor delirium in this challenging patient population.

Aged↗

PubMed1986

Development and optimization of the FAST-ELISA for detecting antibodies to Schistosoma mansoni.

The Falcon assay screening test (F.A.S.T.) system was used to develop a rapid, sensitive, and quantitative kinetic-based enzyme-linked immunosorbent assay (k-ELISA) for detecting antibodies against Schistosoma mansoni adult microsomal antigens (MAMAs). The FAST-ELISA uses polystyrene beads on sticks molded to the lid of a microtitration plate. The beads are coated with antigen. Reagents and sera are placed in microtitration plates and the beads exposed to reagents by immersion. The exposure time required for a single dilution of serum or other antibody source, conjugate, and substrate is 5 min each. Excluding preparation time, two plates can easily be assayed in 30 min. The optima for assay conditions, reproducibility, quantitative linearity, and sensitivity are delineated. A battery of sera from patients with both homologous and heterologous infections was tested, and a dilution series of a standard reference serum pool was included with each test. Results were expressed in number of units as calibrated against the standard reference sera pool. Antigen-coated bead storage studies were performed with untreated and three chemically treated antigens. The storage stability of MAMA, ability to perform the assay with minimal equipment, sensitivity, short assay time, and ease of operation make the FAST-ELISA ideal for field studies.

Antibodies↗

PubMed1999

A multicentre evaluation of the laser assisted ratio analyser (LARA): a novel device for measurement of 13CO2 in the 13C-urea breath test for the detection of Helicobacter pylori infection.

BACKGROUND: The laser assisted ratio analyser (LARA) was developed as a novel device to measure 13CO2 in the urea breath test for the detection of H. pylori infection. The analyser was tested in a prospective multicentre study in 444 patients in North America (Phase 1) followed by second study involving 160 patients (Phase 2). METHODS: Patients undergoing endoscopy for clinical indications had antral and gastric biopsies taken for histological examination, culture and CLO test. One hour after endoscopy, a baseline breath sample was obtained, 100 mg of 13C-urea were ingested and breath samples were obtained at 30 and 60 min post ingestion. Data obtained with the LARA were compared with the results of culture, rapid urease testing and central pathology in two different combinations {reference standards}. The study was conducted in two phases: in Phase 2, a modification was made to the LARA that improved the removal of water vapour from the breath sample. RESULTS: In Phase I, data from 331 patients were analysed using a cut off of (delta) 7.8 +/- 0.8, the sensitivity of the method was 91.7% and the specificity was 86.5%, using the reference standard of 2 of 3 tests (CLO, culture or histology) being positive. Positive and negative predictive values were, respectively, 85.2% and 92.5%. In Phase 2 of the study, 160 patients were enrolled and 141 patients were analysed using the same standards. We used the same reference standards but with a cut off of (delta) 6.1 +/- 0.6. The sensitivity and specificity increased to 96.8% and 98.6%, respectively. Positive and negative predictive values were, respectively, 98.4% and 97.3%. The detection rates for H. pylori were similar in patients with peptic ulcer or H. pylori associated gastritis. CONCLUSIONS: The LARA provides an accurate non-invasive means of detecting 13CO2 in the 13C-urea breath test for H. pylori in a multicentre clinical environment that compares well with invasive 'gold standard' methods.

Adolescent↗

PubMed1997

Identifying relevant diagnostic studies in MEDLINE. The diagnostic value of the erythrocyte sedimentation rate (ESR) and dipstick as an example.

OBJECTIVE: We aimed to examine sensitivity and positive predictive value of MEDLINE searching for diagnostic studies, relevant for the primary health care setting. METHOD: Results of MEDLINE searches were compared with a reference standard collection of studies on two subjects, the diagnostic value of ESR in discriminating between 'pathology' and 'no pathology', and the dipstick method in diagnosing urinary tract infections. The main outcome measures were sensitivity (proportion of the total number of reference standard diagnostic studies that could be identified by the search) and positive predictive value (proportion of the total number of publications retrieved by MEDLINE that were incorporated in the reference standard). RESULTS: The combined MeSH and freetext search was more sensitive than MeSH term searching only, for both the ESR and the dipstick search. With this combined search sensitivities of 0.91 and 0.98 and predictive values of 0.10 and 0.68 were found for ESR and dipstick respectively. By restricting the search with keywords describing the primary health care setting the predictive values increased to 0.72 and 1.00 but sensitivity dropped to 0.10 and 0.07 (ESR and dipstick respectively). CONCLUSION: Combining freetext and MeSH term searching, without restriction to the primary health care setting, is a valuable strategy in systematically searching for available evidence on the value of a diagnostic test in the scope of a specific disease. The predictive value seems to depend on the breadth of the disease area. MEDLINE should provide a term such as 'diagnostic evaluation study' to be used in the limit field Publication Type to specify diagnostic studies.

Blood Sedimentation↗

PubMed1997

[Bronchoalveolar lavage in childhood: technical aspects and reference values].

(BAL) has been increasingly used in recent years also in children. In paediatric pulmonary diseases, however, interpretation has proved difficult in the absence of standard reference values for BAL in childhood. It is the purpose of the present publication to discuss the methodological aspects of BAL in childhood and to proviced criteria by means of standard reference values for the assessment of BAL in paediatric patients. In a group of 50 children aged 3 to 15 years with healthy lungs, who were subjected to BAL during an elective surgical intervention, we examined both cellular and non-cellular components of the BAL. Whereas the percentage of macrophages and lymphocytes in the total population did not differ significantly from the standard values in adults, the absolute and relative granulocyte count was found to be elevated in children under 8 years of age. The CD4/CD8 quotient of BAL was 0.7 on the average, and hence clearly below the standard reference values defined for adults. In the non-cellular components we found an increase in the level of all proteins from plasma, whereas locally produced proteins did not differ from the findings in healthy adults. The total phospholipid content of BAL was markedly enhanced in children below 8 years of age and decreased with increasing age. These differences between children and adults should be taken into account when interpreting pathological findings. They are the basis for better defining the ranking of BAL in paediatric pulmonary diseases.

Adolescent↗

PubMed1989

Theoretical aspects of enzymes in diagnosis. Why do serum enzymes change in hepatic, myocardial, and other diseases?

The pathophysiological mechanisms of leakage, synthesis, and decreased removal of enzyme from blood all play a role in explaining why serum enzymes increase in disease. This presentation has focused on increased synthesis as an important and perhaps major source of increased serum enzymes. The second key point has to do with the reference standard. There is tremendous sophistication in the field addressed to the numerator, that is, biochemical units. The natural tendency is to focus attention on what we want to know in the numerator, the enzyme changes in the tissue. In so doing, however, we tend to ignore the changes of the reference standard in the denominator, which influence the final result as much as the numerator. The following recommendations are made: uniformity, enzyme activities referable to morphological units, and basic biological significance. Total organ per gram initial body weight is recommended as the optimal reference standard whenever possible. If this were done, perhaps we could then resolve the dilemma of the poor understanding of why serum enzymes change in disease. We would, thereby, be better equipped to bring the major part of biochemical pathology out of its infancy as described by Farber.

Animals↗

PubMed1994

New application for the quantitation of cocaine base by gas chromatography.

The analysis of cocaine base is a major part of the forensic drug chemist's workload. Simplifying quantitative methodology can assist the drug chemist. Methods currently employed for quantitation of cocaine base utilize either an internal standard or a direct comparison. This gas chromatographic method for the quantitation of cocaine base employs a non-controlled reference standard and linear transformations. As a result, cocaine base can be quantitated by a single injection of a solution containing the analyte and a non-controlled reference standard of known concentration. Use of this methodology would minimize time expenditures, lower exposure to hazardous solvents and reduce expense of procuring difficult-to-obtain controlled reference standards while limiting detector response variations that can occur with multiple injections.

Alkanes↗

PubMed2005

Determination of platinum-group metals and lead in vegetable environmental bio-monitors by voltammetric and spectroscopic techniques: critical comparison.

This paper reports voltammetric sequential determination of Pt(II), Pd(II), and Rh(III), by square-wave adsorption stripping voltammetry (SWAdSV), and Pb(II), by square-wave anodic stripping voltammetry (SWASV), in vegetable environmental matrices. Analytical procedures were verified by the analysis of the standard reference materials: Olive Leaves BCR-CRM 062 and Tomato Leaves NIST-SRM 1573a. Precision and accuracy, expressed as relative standard deviation and relative error, respectively, were always less than 6% and the limits of detection (LOD) for each element were below 0.096 mug g(-1). Once set up on the standard reference materials, the analytical procedure was transferred and applied to laurel leaves sampled in proximity to a superhighway and in the Po river mouth area. A critical comparison with spectroscopic measurements is discussed.

Biosensing Techniques↗

PubMed2005

Accuracy of radiographer plain radiograph reporting in clinical practice: a meta-analysis.

AIM: To determine the accuracy of radiographer plain radiograph reporting in clinical practice. MATERIALS AND METHODS: Studies were identified from electronic sources and by hand searching journals, personal communication and checking reference lists. Eligible studies assessed radiographers' plain radiograph reporting in clinical practice compared with a reference standard, and provided accuracy data to construct 2 x 2 contingency tables. Data were extracted on study eligibility and characteristics, quality and accuracy. Summary estimates of sensitivity and specificity and receiver operating characteristic curves were used to pool the accuracy data. RESULTS: Radiographers compared with a reference standard, report plain radiographs in clinical practice at 92.6% (95% CI: 92.0-93.2) and 97.7% (95% CI: 97.5-97.9) sensitivity and specificity, respectively. Studies that compared selectively trained radiographers and radiologists of varying seniority against a reference standard showed no evidence of a difference between radiographer and radiologist reporting accuracy of accident and emergency plain radiographs. Selectively trained radiographers were also found to report such radiographs as accurately as those not solely from accident and emergency, although some variation in reporting accuracy was found for different body areas. Training radiographers improved their accuracy when reporting normal radiographs. CONCLUSION: This study systematically synthesizes the literature to provide an evidence-base showing that radiographers can accurately report plain radiographs in clinical practice.

Clinical Competence↗

PubMed2026

Standardisation in the Analytical Characterization of Adeno-Associated Virus (AAV) Vectors.

Adeno-associated virus (AAV) has become a leading vector for in vivo gene therapy, with eight products currently holding marketing authorization. As the field rapidly evolves, the need for robust analytical methods to characterize critical quality attributes (CQAs)-including capsid titer, genome titer, capsid content (empty/full ratio), identity, and purity-continues to grow. Reference Standard Materials (RSMs) play a pivotal role by providing well-characterized, standardized AAV batches that serve as universal benchmarks. RSMs facilitate the validation of emerging analytical technologies, ensure the accuracy and reproducibility of routine assays, and enable inter-laboratory comparability. However, developing universal AAV RSMs is fundamentally constrained by the complex biology, diversity of serotypes, vector genomes, and engineered capsid variants, necessitating serotype-specific and application-specific standards. Recent advances, including the release of pharmacopeial AAV8 reference standards characterized by multiple orthogonal methods, represent meaningful progress toward measurement harmonisation. This review addresses the critical need for RSMs in AAV gene therapy, evaluates the currently available pharmacopeial and commercial standards, and outlines practical strategies for in-house RSM development. Establishing robust, serotype-specific AAV RSMs and harmonised standard operating protocols (SOPs) are essential for advancing AAV gene therapy and ensuring accuracy, reproducibility, and safety across research, development, and clinical manufacturing.

Dependovirus↗

PubMed2002

Assessment of the technology for functional imaging in cancer.

Functional imaging can address hitherto irresolvable questions about cancer biology in both research and practice. In the clinic, by combining features of systemic and local disease markers into reference standards for the diagnosis of new disease entities functional imaging has the potential to literally redefine illness. Clinical assessments can be conducted at two levels: establishment of new reference standards, and evaluation of successor technologies that will substitute for a reference standard in practice. A union of functional imaging with anatomical criteria of disease has shown great promise in the management of numerous cancers. More work is required to use functional imaging to develop 'functional' approaches to diagnosis and therapy. Many methodologies exist for the acquisition of primary data on imaging technology efficacy. A form of economic cost-effectiveness modelling called iterative decision analysis can be used to set research and service priorities. Cancer clinicians need to take an increased role in functional imaging research, as they have primary expertise in the development and use of treatments modifying cell and tissue function.

Decision Making↗