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PubMed1995

An updated standard for clinical electroretinography.

The value of the electroretinogram (ERG) in clinical practice depends in part on its consistency and the ability to compare results with other laboratories and the literature. These issues were addressed by the publication of the International Standard for Clinical Electroretinography in 1989. This Standard provided technical information and defined a core of basic test procedures and test responses (Figure) to ensure that ERGs performed worldwide would be equivalent for clinical and research purposes. Most major laboratories now subscribe to the tenets of the Standard, and it should be noted that the Standard does not limit laboratories from doing additional specialized tests (beyond the recommendations) for either clinical purposes or research. Since science and medicine are not static, the original Standard mandated revision every 4 years by the International Society for Clinical Electrophysiology of Vision. The first revision, titled "Standard for Clinical Electrophysiology (1994 Update)," has just been published, and it contains changes and new provisions that should be reviewed carefully by those who perform ERGs. The major changes and additions in the updated ERG Standard are as follows.

Adult↗

PubMed2002

Inconsistency in evidentiary standards for medical testimony: disorder in the courts.

Several recent decisions by the US Supreme Court have strengthened the ability of federal courts to consider medical testimony regarding injuries associated with exposure to toxic substances. Judges are expected to examine the basis of all expert testimony before it is introduced at trial to ensure that it meets the same standards of intellectual rigor that professionals use outside the courtroom. However, courts have been inconsistent in measuring this testimony against the standards of medical practice, especially when courts consider testimony that is not supported by clinical trials or epidemiological studies. A number of courts have required standards for expert testimony that exceed those that physicians use in ordinary clinical decision making. In this article, we illustrate such inconsistencies across federal courts by contrasting different decisions in cases involving similar facts and expert testimony. We argue that there may be good reason to require a standard of admissibility that exceeds the standards of ordinary clinical decision making, but such requirements are not faithful to the mandate of the Supreme Court. Courts with especially demanding standards are misled if they believe that they are fairly representing medical practice. Physicians should respond by correcting courts' misinterpretations of medical practice and assisting in the development of legal standards that encourage thoughtful and informed consideration of medical testimony by judges and juries.

Expert Testimony↗

PubMed1996

Approaches for assessing the efficacy of occupational health and safety standards.

The regulation of hazards is one of the most dramatic forms of intervention in occupational safety and health (OSH). Despite their high degree of potential social and economic impact, relatively little research has been conducted to specifically evaluate the effectiveness of OSH standards with regard to preventing occupational diseases and injuries. This paper reviews the basic scientific approaches that may be used to evaluate the efficacy of OSH standards. These approaches encompass the following research areas: (1) exposure surveillance, (2) disease surveillance, and (3) prospective studies following the introduction of the standard. Research on asbestos and asbestosis, respirable crystalline silica (quartz) and silicosis, and respirable coal mine dust and coal workers' pneumoconiosis (CWP) are used to illustrate these approaches and the type of information that is currently available. The examples (quartz, coal dust, asbestos) reveal substantial limitations in the types of information currently available for evaluating the efficacy of these OSH standards. Ideally, plans for evaluating the efficacy of OSH standards should be developed for existing and future standards. These plans should include programs for the surveillance of exposures and adverse health effects and, when possible, for prospective studies designed to evaluate how the risk of disease (or injury) is modified by the introduction of the standard.

Forecasting↗

PubMed1990

A clinical study of the automated assessment of intelligence by the Mill Hill Vocabulary test and the Standard Progressive Matrices test.

As part of the Leicester/DHSS project on microcomputer-aided assessment, 274 patients at five clinical sites were assessed with either a computerized version or the standard version of the Mill Hill Vocabulary (Synonyms) test. Of this group, 178 were retested on the alternative version of the test. Similarly, 184 patients were tested with either a computerized version or the standard version of the Standard Progressive Matrices test, of whom 129 were retested on the alternative test form. High correlations were found between the standard and computerized versions for both tests. For the Mill Hill Vocabulary test, no significant difference was found between test versions for first administration, and the vast majority of retested subjects had very similar scores on each version. On the Standard Progressive Matrices, however, subjects obtained significantly lower scores on the computerized test. It is concluded that whereas the computerized Mill Hill Vocabulary test could be used in place of the standard version of clinical settings, the computerized Standard Progressive Matrices test could not be used.

Adolescent↗

PubMed2006

Revising the British Occupational Hygiene Society asbestos standard: 1968-1982.

BACKGROUND: In 1968 the British Occupational Hygiene Society (BOHS) published a chrysotile asbestos hygiene standard. As a consequence of acknowledged inadequacies of the data, it underestimated the risks of exposure, but its influence was international and operated for longer than it merited. Five years later, BOHS reported the standard not to be in need of amending, despite its own doubts and no cognizance having been taken of the cancer hazard. Within months, stung by criticism from Dr. Irving J. Selikoff, industry required it to review the standard, which BOHS continued to do for a number of years before giving up. METHODS: Material obtained for the American Courts by means of legal discovery from an asbestos company's archive, provided information on the membership of the new BOHS committees, and on its operation. RESULTS: Alterations in the composition of the new committees included importantly the introduction of certain independent scientists, whose rigor militated against the ready production of a new hygiene standard acceptable to industry. CONCLUSIONS: There was a time in Britain when a learned society might with impunity omit to consult the views of workers or their representatives when making value judgments about their health and safety, but consider it proper to accede to industry's decision as to what hygiene standard it would accept. Health and Safety at Work legislation in 1974, established an organization on which industry and labor were represented, with the onus for recommending hygiene standards. For several years the BOHS Asbestos Sub-Committee continued attempting to reconcile the interests of industry, until finally abandoning hygiene standard setting as its mission.

Academies and Institutes↗

PubMed1990

Setting human-health-based groundwater protection standards when toxicological data are inadequate.

Toxicological data are not adequate to assess fully the health effects of many of the pesticides that currently contaminate or have the potential to contaminate groundwater. The National Academy of Sciences estimated in 1984 that data to conduct a complete health hazard assessment exist for only 10% of the pesticides currently on the market. Many pesticides have not been tested for their ability to cause cancer, genetic mutation, or birth defects. There are significant gaps in the toxicological data base for the majority of pesticides for which the Environmental Protection Agency proposed health advisories in 1987. To help assure that groundwater standards are adequately protective of human health when toxicological data are not adequate, additional uncertainty factors can be incorporated into such standards. Alternatively, standards can be set at the level of detection. This should be the approach when no data exist to assess major potential health effects. For example, the detection limit could be the standard if no adequate oncogenicity studies have been conducted. In addition, generic standards may be employed when data are inadequate to set chemical-specific standards. New York State has recently taken this innovative generic standard approach.

Databases, Factual↗

PubMedDate not supplied

Standard ECG versus 24-hour Holter monitoring in the detection of ventricular arrhythmias.

A total of 386 corresponding registrations of standard ECG and 24-h Holter monitoring were compared in order to elucidate the information obtainable from a 60-s standard ECG with regard to ventricular arrhythmias. Ventricular ectopic beats (VEB) were present on 17% of the standard ECG against 90% of the monitorings (p less than 0.001). The corresponding figures for complicated VEB (multiform, repetitive, R on T) were 2% and 41%, respectively (p less than 0.001). The presence of VEB on the standard ECG was associated with a significantly increased incidence of all types of ventricular arrhythmias during Holter monitoring performed within the same day. The number of VEBs on the standard ECG did not predict the number during monitoring, but to some extent did predict the occurrence of complicated types. In 52 patients free from VEB on four consecutive standard ECGs, Holter monitoring showed complicated ectopic activity in 32 (62%). Thus standard ECG is an insensitive method for the detection of ventricular arrhythmias.

Arrhythmias, Cardiac↗

PubMed1995

Fluorescent erythrocyte ghosts as standards for quantitative flow cytometry.

We report here a quick and inexpensive method for preparing standards of known fluorochrome content for calibration and quantitation of flow cytometry fluorescence signals. Erythrocyte ghosts prepared by hypotonic lysis are filled with solutions containing fluorescently labeled dextran. Standards prepared by this technique have a narrow range of fluorescence and a linear response of fluorescence to fluorochrome content up to 2 x 10(6) fluorochrome molecules/cell. The volume of ghost standard particles is roughly 70 femtoliters (fl)/cell. The fluorescence of ghost standards is nearly identical to that of commercially available microbead standards of similar fluorochrome content. Ghost standards have stable fluorescence for at least 3 weeks at 4 degrees C. These standards can be made with any fluorochrome or combination of fluorochromes over a wide concentration range.

Erythrocyte Membrane↗

PubMed1983

Standard sera in solid-phase immunoassays.

Solid-phase immunoassay-derived antibody titers are often converted to weight unit concentrations with the aid of standard sera containing known antibody concentrations. Systematic studies justifying this procedure have not yet been published. We therefore investigated the magnitude of errors associated with this conversion. Antibody concentrations of thirteen sera or ascites fluids were determined by quantitative precipitation or equilibrium dialysis, and one was then used as a "standard antibody" for the others in solid-phase radioimmunoassay (SP-RIA) or enzyme-linked immunosorbent (ELISA) assays. Antibody concentrations determined by the conventional solid-phase assay (the "standard serum" has the same specificity as the "sample") had up to fourfold errors. These errors could be reduced by basing the conversion on the combination of two standard sera instead of one. The possibility was studied of whether the conversion to weight units could be done with the aid of a standard serum directed to a different antigen than the sample antibody. Errors associated with the use of such a heterologous standard were not significantly greater than those found using the conventional conversion. A combination of two reference sera again reduced the errors. The use of such heterologous standard(s), however, requires checking the binding capacity of the antigen coats.

Animals↗

PubMedDate not supplied

The 1989 CARF nursing standards: guidelines for implementation. Commission of Accreditation of Rehabilitation Facilities.

Since its earliest days, the Commission on Accreditation of Rehabilitation Facilities (CARF) has shown its commitment to maintaining its standards to reflect the current practice of rehabilitation. At a task force convened in 1988, a group of experts in rehabilitation was charged with the revision of the standards that addressed comprehensive inpatient rehabilitation. This task force included rehabilitation nurses who could identify and address the elements of rehabilitation nursing that are essential to any comprehensive inpatient rehabilitation setting. Recognizing that there are implications for rehabilitation nursing throughout the standards, it was felt that the standards that are specific to the practice of rehabilitation nursing should be expanded to address the quality and quantity of rehabilitation nursing in the inpatient setting, as well as the integration of the specialty of rehabilitation nursing into a truly comprehensive rehabilitation program. The outcome of this endeavor is the revision of the standards for rehabilitation nursing, which can be found in the 1989 Standards Manual for Organizations Serving People with Disabilities. The actual nursing standards, found in section III A of the manual, are reprinted here with permission of CARF.

Humans↗

PubMed1989

Applied biomaterials standards report.

The purpose of my column is to provide readers with current information on biomaterials-related standards produced by both private groups and government agencies, and standards-related activities. Standards are descriptive documents given official status by their producers and, in the case of biomaterials, they are generally intended to provide formalized descriptions of (a) materials used in the construction of medical devices, (b) materials used directly in surgical repairs, (c) test methods to evaluate materials for such applications, and (d) methods for handling or processing such materials. Please consider this column not only a place to obtain biomaterials standards information but also a place to submit news of biomaterials standards developments in order to get the information before the public. This invitation extends to all members of any and all professional organizations and government agencies in the United States and abroad who are active in standards development and would like specific activities or standards publicized. I will present the information in this column to the extent that allotted space allows. And last, a caveat--since this is a column, it contains both factual information and opinions. I will make every effort to make it clear which is which. Also, as a frame of reference, please note that this column was written and submitted in January, 1989.

Biocompatible Materials↗

PubMed2005

Human fibroblast reactions to standard and electropolished titanium and Ti-6Al-7Nb, and electropolished stainless steel.

Stainless steel (SS), titanium (cpTi), and Ti-6Al-7Nb (TAN) are frequently used metals in orthopedic internal fracture fixation. Although reactivity to SS and cpTi are noted in reference, the soft tissue compatibility of TAN has not been comprehensively studied. This study focuses on the in vitro soft tissue compatibility of TAN in comparison to SS and cpTi using a human fibroblast model. The industrial standard surface finishes of these three materials vary considerably in view of their use in similar applications. To distinguish between material parameters of topography and chemistry, we have included electropolished (e.p) counterparts of the standard preparations of cpTi and TAN in the study (standard SS is e.p). All materials were characterized using atomic force microscopy, profilometry, and scanning electron microscopy. Our findings demonstrate that cell morphology and growth rate was similar for SS, and e.p. cpTi and TAN, with cells well spread and forming a confluent monolayer by 10 days. Cell growth on standard cpTi was similar to the electropolished samples; however, they showed a less spread morphology with more filopodia and surface ruffling present. Cell morphology on standard TAN was rounded or elongated and proliferation was inhibited at all time points, with possible cell necrosis by day 10. We found evidence of endocytosis of beta-phase particles originating from the standard TAN surface. We believe that the particle uptake coupled with the characteristic surface topography contribute to the noncytocompatibility of fibroblasts on standard TAN.

Biocompatible Materials↗

PubMed1994

Universal standardization for dual x-ray absorptiometry: patient and phantom cross-calibration results.

The comparison of patient data among different dual x-ray absorptiometry (DXA) scanners is complicated because no universally accepted cross-calibration procedure or standard currently exists. This study was performed under the auspices of the International DXA Standardization Committee to establish appropriate cross-calibration parameters. Posteroanterior (PA) lumbar spine measurements of 100 women, ages 20-80 years (mean 52.6 +/- 16, range of BMD = 0.4-1.6 g/cm2) were obtained on a Norland XR26 Mark II, a Lunar DPX-L, and a Hologic QDR 2000 densitometer using standard procedures (pencil beam mode for all three scanners). Area, BMC, and BMD results from the different scanners were compared for all patients. In addition, the European spine phantom (ESP) and the European spine phantom prototype (ESP prototype), as well as standard phantoms from all three manufacturers, were evaluated on the three systems. To achieve universal scanner calibration, we used the intercept and slope of the patient's correlations and the value of the middle vertebra of the ESP as a reference point in a series of standardization formulas, and we have expressed the results as sBMD (mg/cm2). The correlations of the patients' spinal BMD values were excellent for each of the three scanner pairs. The average absolute difference in patient spinal BMD values (L2-4) between Hologic and Norland was 0.012 g/cm2 (1.3%); it was 0.113 g/cm2 (11.7%) between Hologic and Lunar and 0.118 g/cm2 (12.2%) between Norland and Lunar. The phantoms' regression lines approximated those of the patient regression lines, and the phantoms with only one measurement point were very close to the patients' regression lines. After applying the standardization formulas, the average absolute differences for the 100 patients were 28 mg/cm2 (2.7%) for Hologic/Norland, 23 mg/cm2 (2.2%) for Hologic/Lunar, and 29 mg/cm2 (2.8%) for Norland/Lunar. Average BMD results for the patients before correction were 0.972 mg/cm2 for Hologic, 1.100 g/cm2 for Lunar, and 0.969 g/cm2 for Norland. After correction, sBMD results for patients were 1045 mg/cm2 for Hologic, 1047 mg/cm2 for Lunar, and 1043 mg/cm2 for Norland. The standardization approach as performed in our study provided compatibility of DXA results obtained on different scanners.

Absorptiometry, Photon↗

PubMed1992

Quality assurance and standards in hematopoietic progenitor processing.

Bone marrow transplantation is an increasingly important therapeutic procedure. As more laboratories have become involved in the processing of hematopoietic progenitor cells from marrow or blood, it has been recognized that standards are required for hematopoietic progenitor processing, storage, and handling. Quality assurance is the process of monitoring whether laboratory procedures, equipment, and personnel fulfill their expected functions, and the aim of quality assurance is to ensure compliance with standards. Some standards for hematopoietic progenitor processing have recently been issued by professional organizations. Although these standards are not comprehensive, where applicable they should be met or exceeded. In the absence of published standards, principles of good laboratory practice should guide quality assurance programs. This article presents concepts of quality assurance in hematopoietic progenitor processing, based on standard laboratory practice and published standards.

Blood↗

PubMedDate not supplied

Evaluation of fetal growth by ultrasonography in twin pregnancy: a comparison between individual and cross-sectional growth curve standards.

Cross sectional curves and individual fetal growth curves standards from the Rossavik growth model [P = c(t)(k + s(t]] were generated for abdominal and head circumferences, femur diaphysis length and estimated fetal weight from a sample of 59 women with twin pregnancy. These curves were compared to their counterparts in singleton pregnancies. Cross sectional curves of the four fetal anatomic parameters under study fell progressively below the curves for singletons during the last trimester of gestation. In contrast, there were few differences between individual fetal groWth curve standards for twin and singleton pregnancies. In 11 of the 59 patients, both methods were used to evaluate fetal growth in the last trimester of gestation. In 5 of these patients, fetal growth was normal by both methods in all 10 fetuses. In the 6 other patients, there were 3 fetuses with abormal estimated fetal weights (EFWs) by both population and individual standards. However, 3 fetuses had abnormal EFW's by populations standards but not by individual standards while the EFW of another fetus was abnormal by individual standards but not by population standards. These results illustrate that the cross-sectional approach to the assessment of growth in twins can be misleading and may lead to incorrect conclusions concerning the growth of these fetuses.

Embryonic and Fetal Development↗

PubMedDate not supplied

Is 3-dimensional volume sonography an effective alternative method to the standard 2-dimensional technique of measuring the nuchal translucency?

PURPOSE: To determine whether 3-dimensional (3D) volume scanning is an effective alternative method of measuring nuchal translucency in first-trimester fetuses compared with the standard 2-dimensional (2D) technique, and to report a standardized method of evaluation. METHODS: We measured the nuchal translucency of 29 fetuses between 11.4 and 13.9 weeks of age using the standard 2D sonographic technique with the fetus in a sagittal view. We then rescanned the fetus in a coronal orientation and obtained a 3D volume of the fetal neck area from crown to rump using a consistent technique. The sagittal orientation was reconstructed, and the width of the nuchal translucency was measured electronically using the reconstructed midsagittal view. The measurements using a conventional 2D sagittal view were then compared with the 3D reconstructed sagittal view. The nuchal translucency was adequately measured in all fetuses in which the 3D assessment was attempted. RESULTS: The nuchal translucencies of 29 consecutive fetuses were measured using both 2D and 3D multiplanar reconstruction of the fetal neck. The mean +/- standard deviation for the standard 2D assessment of the nuchal translucency was 1.7 +/- 1.4 mm. Using 3D reconstruction of the Z plane, the measurement was 1.8 +/- 1.6 mm. This was not a statistically significant difference (P = 0.4). There was a very high correlation between the two techniques (r = 0.984, P < 0.001). CONCLUSIONS: There is an excellent correlation between the measurements of the nuchal translucency using standard 2D scanning and those obtained from 3D multiplanar reconstruction of the Z plane. Using a consistent technique, the nuchal translucency can be accurately and reliably measured with a 3D rendering. This technique is potentially useful in fetuses that are not in an optimal position for standard 2D nuchal translucency measurement.

Embryo, Mammalian↗

PubMed2002

Standardization using the harmonically weighted ratios: internal and external comparisons.

Standardization of rates is a basic tool for epidemiologists. The most frequently used methods are the 'direct standardization' (with summary index of comparative mortality figure, CMF) and the 'indirect standardization' (with summary index of standardized mortality ratio, SMR). The CMF facilitates a valid comparison between populations or across time periods, yet, it suffers from the problem of instability. By contrast, the SMR is stable and can be used for external comparison. However, it cannot guarantee a valid internal comparison. In this paper, the author proposes a new standardized measure, the 'harmonically weighted ratio' (HWR). The HWR can be used for external as well as internal comparisons--with the assumption of rate-ratio homogeneity, or with heterogeneity but dominance of one population over another. Simulation shows that its performance in terms of pairwise comparisons is the best among the three methods or compares favourably to that of the SMR. The author also examines the behaviours of the HWR when used for hypothesis testing (the 'HWR test'). The HWR can be considered for standardization when the purpose of the standardization is solely for comparison and when the universe of the comparisons can be clearly defined.

Adolescent↗

PubMed2002

Calibration of replacement international standard and European pharmacopoeia biological reference preparation for tetanus toxoid, adsorbed.

Here we report the characterisation of a preparation of tetanus toxoid, adsorbed, and its calibration by 27 laboratories in 19 countries in a joint international collaborative study co-sponsored by World Health Organization (WHO) Expert Committee of Biological Standardization (ECBS) and the European Biological Standardisation Programme of European Directorate for the Quality of Medicines (EDQM), Council of Europe. Calibration was in terms of the Second International Standard (I.S.) for Tetanus Toxoid, Adsorbed, by the established WHO/European Pharmacopoeia (Ph Eur) challenge methods. The replacement standard preparation was found to have a unitage of 469 IU/ampoule on the basis of its calibration in guinea-pigs and 496 IU/ampoule on the basis of its calibration in mice. Assessment, both within the collaborative study and as part of candidate characterisation, indicated satisfactory stability of the candidate preparation. This study also provided some information on the effect of mouse strain on potency testing of tetanus vaccines. A limited assessment of the impact of the replacement standard on testing of current production batches of vaccines was also carried out by four manufacturers. This study did not directly address the serological approaches to potency testing. However, one laboratory offered data from mouse serology assay, which gave comparable estimates to in vivo mouse bioassay. Based on the results of this study and with the agreement of participants, the candidate standard was established as the Third International Standard for Tetanus Toxoid, Adsorbed (coded 98/552) by the WHO Expert Committee of Biological Standardization (ECBS) in November 2000. The same preparation was also established as the second Ph Eur Biological Reference Preparation (Ph Eur BRP, batch no. 2) by the Steering Committee of the Biological Standardisation Programme of the EDQM and approved by the European Pharmacopoeia Commission.

Animals↗