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PubMed2005

Influence of reagent formulation on mRNA quantification by RT-PCR using imported external standard curves.

Use of an imported external standard curve is common in real-time quantitative RT-PCR. Two practical strategies for long-term experiments include importing a grand mean standard curve to all accumulated runs or using daily imported standard curves, fixing the slope at the beginning of the experiment and calibrating successive runs with curves generated from this imported slope, adding a single standard that registers the variation in the y-intercept. This study determines the influence that a change in reagent lots has on these two calibration approaches when determining mRNA copy numbers of the ornithine decarboxylase and porphobilinogen deaminase genes. Two sets of determinations were run with the use of lot A and lot B. A marked decrease in the crossing points (Cp) in the standards for both genes at all concentration levels was observed with the change in lots. A grand mean standard curve was generated for each gene and each set and comparisons between the sets were performed. Statistically significant differences were found with respect to the y-intercept but not the slope, suggesting that the change of reagent lot affected the detection sensitivity but not the efficiency of the reaction. The excellent correlation coefficients obtained for these curves for each gene were not achieved when overall data from both sets were combined to generate an overall grand mean standard curve. We conclude that when faced with a change of RT-PCR reagent lot that will affect the detection sensitivity of the method, samples should be calculated with either the daily imported standard curves or with the respective grand mean standard curve for each lot.

Base Sequence↗
PubMed1989

The Centers for Disease Control-National Heart, Lung and Blood Institute Lipid Standardization Program. An approach to accurate and precise lipid measurements.

In collaboration with the National Heart, Lung, and Blood Institute, the CDC has supported programs for standardizing lipid measurements for more than 30 years. These programs were begun because comparable and accurate quantitative measurements were needed for epidemiologic studies of coronary heart disease. Since the first program was initiated, over 500 national and international laboratories have participated in the various CDC lipid standardization programs. The cornerstone of these standardization programs has been an accuracy base of lipid reference materials and methods developed by CDC. Specifically, CDC has developed human, serum-based reference materials for cholesterol, HDL, triglyceride, and apolipoproteins A-I and B and reference methods for total cholesterol, HDL, and triglyceride. The CDC reference method for cholesterol has been adopted as the national reference method for cholesterol by the National Reference System for the Clinical Laboratory Council of the National Committee for Clinical Laboratory Standards. The approved CDC reference method along with an approved NBS definitive method, an approved NBS certified Reference Material, and the CDC certified serum-based secondary reference materials make up the accuracy base for serum cholesterol measurements in the United States, and together they are recognized as the National Reference System for Cholesterol. The NCEP Laboratory Standardization Panel recommends that cholesterol measurements made by all clinical laboratories should be standardized so that cholesterol values are traceable to the National Reference System for Cholesterol. In support of the NCEP's efforts, CDC will establish a standardization program permitting the laboratory and manufacturing community to trace cholesterol measurements and the development of cholesterol diagnostic products back to the national reference system. The major emphasis of this standardization effort is to establish a network of reference method laboratories (1) to assign cholesterol values to all commercially prepared lots of calibrators and control materials and (2) to provide reference measurements on individual "fresh" human serum specimens to manufacturers and clinical laboratories. CDC is also working to (1) provide reference materials to manufacturers, (2) collaborate with NBS to maintain documentation of the national reference system accuracy base, (3) cooperate with proficiency testing organizations to assist in the accurate labeling of reference materials, and (4) provide training and education pertinent to cholesterol standardization.(ABSTRACT TRUNCATED AT 400 WORDS)

Centers for Disease Control and Prevention, U.S.↗
PubMed1985

Determination of serum ferritin by a one-step immunoenzymoassay, and comparison of four liver-ferritin standards.

We describe a one step "sandwich"-type immunoenzymoassay for ferritin in human serum. The solid-phase consists of glutaraldehyde-treated polypropylene tubes coated with rabbit antibody to human ferritin. Liver ferritin is the standard. Peroxidase-conjugated antiserum to ferritin and a sensitive chromogen, o-phenylenediamine, are used. The assay requires 90 min. The standard curve is linear up to 400 micrograms of ferritin per liter of serum. Within- and between-run CVs are less than 6% for low, high, and medium concentrations and are about 13.0% at the decision level for iron deficiency. Results by a two-step "sandwich" procedure (New England Immunology Associates kit) correlated well, r = 0.98. We assessed four liver ferritin standards from different manufacturers with the described method. The mean absorbance for the 40 micrograms/L ferritin standard was 1.5 for that from Diagnostics Biochem and National Institute for Biological Standards and Controls, 1.0 for that from Dako, and 0.4 for that from Sigma. Consequently, to standardize results, all liver ferritin standards should be calibrated vs the National Institute for Biological Standards and Controls reference standard.

Animals↗
PubMed1993

[Determination of the standard level of serum erythropoietin in relation to hemoglobin concentration].

Serum erythropoietin (EP) concentration was measured by the recombinant EP-based radioimmunoassay and was examined to standardize the hemoglobin (Hb) related level of 144 normal control and 56 patients with iron deficiency anemia and hemolytic anemia excluding paroxysmal nocturnal hemoglobinuria. The standardization was achieved by logarithmic regression of the EP titier on Hb either by the two-phase linear form or by the third degree sigmoid form at a 95% confidence limit for each regression. The third degree regression was found to be preferable from the view point of both statistics and the negative feedback mechanism. The average and scattering of the deviation from the standard level thus determined of the disease groups indicated that the EP level is: (1) 12 fold higher than the standard level in 42 aplastic anemias (the most in excess and a few in standard). (2) three fold higher than that in 27 myelodysplastic syndromes (relatively higher dispersed state). (3) 29% of the standard level in 33 anemias associated with chronic renal failure (deficient state). (4) 105% of the extrapolated standard level in 22 polycythemia veras (standard state). The standardization of Hb-related Ep titer may provide new pathophysiological approaches in a variety of hematopoietic disorders.

Anemia, Hemolytic↗
PubMed1996

[Standardization of quantitative measurement of rheumatoid factor].

Recently many automated methods have been developed for a quantitative measurement of rheumatoid factor (RF). As they are widely used, it has been claimed that estimated values of RF are quite different among institutions. Standardization of quantitative measurement of RF is, therefore, required. The subcommittee for standardization of RF of the Ministry of Health and Welfare of Japan, worked from 1988 to 1994 in order to obtain an appropriate national standard of RF and has reached the conclusion that murine monoclonal rheumatoid factor (mRF) would be recommended as a new national standard of RF, which allows new expression of RF value (microgram/ml equivalent to the mRF instead of unit/ml referred to the WHO standard). There are two types of methods widely used for the quantification of RF. The first type is a method of light scattering analysis which is based on interaction of RF with particle-coated or aggregated human IgG (Fc) in nepherometry or turbidimetry, RF being expressed as unit/ml referred to the WHO standard. The second is a radioimmunoassay or an enzyme immunoassay in which RF is expressed as index compared to arbitrary standard. The former expression of RF is recognized to indicate agglutination titer of RF and the latter expresses the concentration of RF. The subcommittee decided to target on the former type of methods because of rapid prevalence with large inter-laboratory variations. The mRF is able to agglutinate proportionally IgG-complex with various features in wide range (x x microgram/ml to more than 1 mg/ml). It can be measured by nepherometry and turbidimetry with sufficient stability. The mRF has no misgivings in present and future supply and in immutability after a century. One of the largest advantages of the use of mRF national standard is expected to be able to eliminate the inter-laboratory variations of RF values which are considered to be mainly derived from different methods of laboratory instruments as well as from biological properties of polyclonal RF. The use of microgram/ml equivalent to mRF instead of unit/ml referred to the WHO standard makes it possible to determine the exact RF value of test serum since the mRF preparation could be adjusted to the best concentration to be requested by any available method of instrument to measure agglutination titer of RF.

Animals↗
PubMed2026

Addition of High-Dose Vitamin D3 to Standard Treatment in Patients With Metastatic Colorectal Cancer: The SOLARIS Randomized Clinical Trial (Alliance A021703).

IMPORTANCE: In a phase 2 randomized clinical trial, high-dose vitamin D3 added to standard treatment improved progression-free survival (PFS) compared with standard-dose vitamin D3 in patients with metastatic colorectal cancer (mCRC). OBJECTIVE: To determine if high-dose vitamin D3 added to standard chemotherapy improves outcomes in patients with previously untreated mCRC. DESIGN, SETTING, AND PARTICIPANTS: Double-blind phase 3 randomized clinical trial enrolling 455 patients with previously untreated mCRC, conducted in the US through the National Clinical Trials Network from October 2019 to December 2022 (database freeze: July 15, 2024). INTERVENTIONS: mFOLFOX6 (modified FOLFOX6 [5-fluorouracil, leucovorin, oxaliplatin]) or FOLFIRI (5-fluorouracil, leucovorin, irinotecan) plus bevacizumab every 2 weeks with either high-dose vitamin D3 (8000 IU daily × 14 days as loading dose followed by 4000 IU daily) or standard-dose vitamin D3 (400 IU daily) until disease progression, intolerable toxicity, or withdrawal of consent. MAIN OUTCOMES AND MEASURES: The primary end point was PFS assessed by the unstratified log-rank test. Secondary end points included objective response rate, overall survival, and toxicity. Prespecified subgroup analyses of PFS were performed according to known prognostic factors. RESULTS: Among 455 randomized patients (median age, 59 years; 181 [40%] female) with median follow-up 20 months, the median PFS for high-dose vitamin D3 (n = 228) was 11.8 months (95% CI, 10.3-13.3) vs 10.3 months (95% CI, 9.4-12.2) for standard-dose vitamin D3 (n = 227) (1-sided log-rank P = .25). There were no significant differences in objective response rate between high-dose and standard-dose vitamin D3 (51% [95% CI, 44%-58%] vs 44% [95% CI, 37%-50%], respectively; P = .12), or in overall survival (median, 25.6 vs 27.0 months; 1-sided log-rank P = .66). There were no clinically meaningful differences in the most common grade 3 or greater adverse events between the high- and standard-dose groups, including neutropenia (n = 67 [32%] vs n = 62 [30%]) and hypertension (n = 42 [20%] vs n = 49 [23%]) or in incidence of vitamin D-associated toxicities. CONCLUSIONS AND RELEVANCE: Among patients with previously untreated mCRC, addition of high-dose vitamin D3, vs standard-dose vitamin D3, to standard chemotherapy plus bevacizumab did not improve PFS. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04094688.

Aged↗
PubMed2003

Historical review of RF exposure standards and the International Committee on Electromagnetic Safety (ICES).

Focused research on the biological effects of exposure of humans and animals to radio frequency (RF) and microwave energy goes back at least five decades. The history of committees that develop safety standards based on the results of this research goes back almost as far. One such committee that has played a major role in developing such standards is the International Committee on Electromagnetic Safety (ICES), which began in 1960 as the American Standards Association C95 Committee. This paper briefly reviews the history of this committee and its role in the development of RF safety standards. The process now being followed by ICES and its sponsor, the IEEE Standards Association Standards Board (SASB), is discussed, as are a number of issues related to standards setting, such as the poor quality of much of the research and the seemingly endless speculation and search for mechanisms of interaction other than heating. Finally, a tribute is given to Dr. Eleanor Adair, a long-time researcher and supporter of science-based standards. As Chairman of ICES, she makes it clear that her goal and the goal of ICES is to establish rational standards that will make future beneficial applications of RF energy credible to humanity.

Advisory Committees↗
PubMed2003

Addition of the neurokinin 1 receptor antagonist aprepitant to standard antiemetic therapy improves control of chemotherapy-induced nausea and vomiting. Results from a randomized, double-blind, placebo-controlled trial in Latin America.

BACKGROUND: Aprepitant is a novel neurokinin 1 (NK(1)) antagonist that has been shown to improve control of chemotherapy-induced nausea and vomiting (CINV) when added to a standard antiemetic regimen of a 5-hydroxytriptamine-3 antagonist plus a corticosteroid. The authors sought to evaluate further the efficacy and tolerability of aprepitant plus standard therapy in a large clinical trial. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled, parallel-groups, Phase III study. Patients with cancer who were scheduled to receive treatment with high-dose cisplatin chemotherapy were randomized to receive 1 of 2 treatment regimens; the standard therapy group received intravenous ondansetron 32 mg and oral dexamethasone 20 mg on Day 1, and oral dexamethasone 8 mg twice daily on Days 2-4. The aprepitant group received oral aprepitant 125 mg, intravenous ondansetron 32 mg, and oral dexamethasone 12 mg on Day 1; oral aprepitant 80 mg and oral dexamethasone 8 mg once daily on Days 2-3; and oral dexamethasone 8 mg on Day 4. Patients recorded episodes of emesis, use of rescue therapy, and severity of nausea in a diary. A modified intent-to-treat approach was used to analyze the efficacy data. The primary endpoint was complete response (no emesis and no rescue therapy) during the 5-day period postcisplatin. Treatment comparisons were made using logistic regression models, and reported adverse events and physical and laboratory assessments were used to assess tolerability. RESULTS: A total of 523 patients were evaluated for efficacy, and 568 patients were evaluated for safety. During the 5 days after chemotherapy, the percentages of patients who achieved a complete response were 62.7% in the aprepitant group (163 of 260 patients) versus 43.3% in the standard therapy group (114 of 263 patients; P < 0.001). For Day 1, the complete response rates were 82.8% for the aprepitant group and 68.4% for the standard therapy group (P < 0.001); for Days 2-5, the complete response rates were 67.7% in the aprepitant group and 46.8% in the standard therapy group (P < 0.001). The overall incidence of adverse events was similar between the 2 treatment groups (72.8% in the aprepitant group [206 of 283 patients] and 72.6% in the standard therapy group [207 of 285 patients]) as were rates of serious adverse events, discontinuations due to adverse events, and deaths. CONCLUSIONS: In patients with cancer who are receiving high-dose cisplatin-based chemotherapy, therapy consisting of aprepitant (125 mg on Day 1 and 80 mg on Days 2-3) plus a standard regimen of ondansetron and dexamethasone provided superior antiemetic protection compared with standard therapy alone and was generally well tolerated.

Adolescent↗
PubMed1996

Modular extension of the ACR-NEMA DICOM standard to support new diagnostic imaging modalities and services.

The American College of Radiology-National Electrical Manufacturers Association (ACR-NEMA) Standard for Digital Imaging and Communications in Medicine (DICOM) (NEMA PS3-1993, DICOM) enables interconnection of imaging equipment and exchange of diagnostic images over standard networks. The widespread adoption of DICOM by industry and the benefits of standardized image management have attracted international attention. Other medical specialties, dentistry, and veterinary medicine have indicated strong interest in extending the DICOM Standard to support nonradiological image modalities. Parts 1 through 9 of DICOM were published in 1992 and 1993. Additional features developed in response to requests from the user community are being added in DICOM Supplements. The ACR, NEMA, and committees from other medical specialties working under the coordination of the American National Standards Institute Healthcare Informatics Standards Planning Panel Message Standards Developers Subcommittee Joint Working Group for Diagnostic Image Communication have defined new image object classes to support X-Ray Angiography, Radio-Fluoroscopy, Positron Emission Tomography, Endoscopy, and Light Microscopy. ACR-NEMA has also developed new service classes for Storage Commitment and Worklist Management. In joint work with the standards development committee of the Japanese Industries for Radiation Apparatus and the Japanese Medical Information System Development Center, ACR-NEMA has developed specifications for multibyte character set support and for a DICOM file format for transportable media. Other work is in progress. New DICOM features have provided and can continue to provide significant new functionality for digital image management systems. The demonstrated capability of efficient extension of the base standard is evidence of the effectiveness of the object oriented strategy of DICOM.

Diagnostic Imaging↗
PubMed2002

Secondary pH standards and their uncertainty in the context of the problem of two pH scales.

Establishing a traceability route with all measurement and uncertainty relationships determined is an important aspect of traceability, and seems to be particularly striking in pH measurement. In this paper the issue of evaluation of secondary pH standards measured with reference to a primary standard in a differential cell with free diffusion type liquid junctions is considered. Relatively high uncertainty, U=0.015, has been assigned to such standards in the recent IUPAC Recommendations on pH (2001), because of a specific residual liquid-junction potential treated statistically as a contribution to the combined uncertainty. Close inspection of the problem leads to the conclusion that a correction for the residual liquid-junction potential should be applied to the measured value of a secondary pH standard. This can be considered as a correction for a known systematic effect on the traceability route. With available experimental data it is demonstrated that such a correction can reasonably be made for well-studied standard buffer systems. In this way the uncertainty associated with secondary pH standards is kept to a low level, and, what is more, the problem of two pH scales, a multi-standard scale and a single-standard scale, gains a proper solution. The need for different treatment of residual liquid-junction potentials at different levels in the measurement hierarchy is noted. Much attention is also given to rational categorization of pH standards in the hierarchy.

Journal Article↗
PubMed2005

The effect of race/ethnicity and insurance in the administration of standard therapy for local breast cancer in Florida.

OBJECTIVES: Assess the effect of race/ethnicity and insurance coverage on the receipt of standard treatment for local breast cancer. METHODS: Local breast cancers diagnosed between July 1997 and December 2000 and reported to Florida's registry were linked to the Agency of Healthcare Administration inpatient and outpatient databases, resulting in 23,817 female local breast cancers with informative treatment. Standard treatment was defined as mastectomy or breast-conserving surgery followed by radiation therapy and it was modeled as a function of health insurance and race/ethnicity accounting for age at diagnosis, marital status and facility type. RESULTS: Approximately 88% of the local breast cancers received standard treatment. The likelihood of standard treatment decreased by 3% per year of increase in the age at diagnosis. Compared to white non-Hispanic, black non-Hispanic women were 19% less likely to receive standard treatment (OR=0.81, 95%CI=0.68, 0.97) and Hispanics were 23% less likely (OR=0.77, 95%CI=0.66, 0.89). Local breast cancers diagnosed in non-teaching facilities were 21% more likely to receive standard treatment compared to those diagnosed in teaching facilities (OR=1.21; 95%CI=1.05, 1.38)). Compared to single, married women were 51% more likely to get standard treatment (OR=1.51, 95%CI=1.31, 1.66), followed by separated or divorced women that were 37% more likely (OR=1.37, 95%CI =1.13, 1.66). Compared to the privately insured, Medicare beneficiaries were 36% more likely to receive standard treatment (OR=1.36, 95%CI=1.22, 1.51) whereas the uninsured were 24% less likely (OR=0.76, 95%CI=0.59, 0.96); Medicaid insured women were 29% less likely to receive standard treatment compared to the uninsured (OR=0.71, 95%CI=0.53, 0.96). CONCLUSION: Future efforts should target the elderly, Hispanic and black women, the uninsured, and those on Medicaid in order to reduce treatment disparities.

Adolescent↗
PubMed1994

The role of standards in creating a health information infrastructure.

In the belief that the existence of a variety of standards is an absolute necessity for health care professional workstations to work, this paper provides a detailed overview of the standards efforts of a number of groups. According to the International Standards Organization (ISO) Reference Model, workstations require a full level of standards from the physical level through and beyond the applications level. Rapidly changing technology challenges acceptance of standards at the lower levels. Current recommendations include fiberoptic media using certain protocols. Other standards in these lower levels also have support. At the applications level, data messaging standards are being developed by six groups. The consensus standards body for the United States is coordinating the efforts of these groups in order to produce a harmonized effort, and is coordinating the effort with Europe for an international effort. Work on the development of the full set of standards necessary for workstation implementations is lagging. Accelerating the process is mandatory if we are to achieve the necessary seamless interoperability required by workstations for ubiquitous intelligent communications between the workstations and the sources of data.

Database Management Systems↗
PubMed1990

Long-term behavioral and learning abnormalities produced by the irreversible cholinesterase inhibitor soman: effect of a standard pretreatment regimen and clonidine.

Previous studies in this laboratory have demonstrated that the alpha 2-adrenergic agonist clonidine and related drugs can offer significant protection against both the acute and chronic toxicity to soman administration in rats and mice. The purpose of this study was to determine whether addition of clonidine to a standard pretreatment protective regimen against soman toxicity could offer added protection or benefit. The standard regimen employed was a mixture of physostigmine salicylate (150 micrograms/kg) and artane (trihexyphenidyl hydrochloride 2 mg/kg). Rats were randomly assigned to one of 4 experimental groups: (1) those receiving i.m. sterile saline injection followed 30 min later by s.c. saline injection (normal controls); (2) saline, i.m. followed 30 min later by one of several doses (60-110 micrograms/kg of soman, s.c.; (3) saline, i.m., followed 10 min later by the standard pretreatment regimen i.m., followed by one of several doses of soman (160-300 micrograms/kg), s.c.; and (4) clonidine hydrochloride (1 mg/kg) i.m., followed 10 min later by the pretreatment regimen, followed 30 min later by soman. All animals were examined acutely and survivors were examined over a 3-week period following soman administration. The following observations were made: (1) Addition of clonidine to the standard pretreatment regimen did not enhance survival rate over the standard regimen alone (unless the clonidine was administered after the regimen). (2) Of the acutely toxic behavioral signs promoted by soman, clonidine addition to the standard regimen was of benefit only in reducing soman-induced tremor. (3) Addition of clonidine to the standard regimen appeared to hasten the return to normal motor behavior after soman; however, all groups exhibited normal motor behavior in 9 days. (4) Despite apparent normal motor behavior, soman-treated animals exhibited a marked performance deficit in the passive avoidance parameter 3 weeks after injection. The standard regimen partially preserved this effect; addition of clonidine to the standard regimen completely reversed the effect. These results indicate that clonidine provides a measure of protection against chronic behavioral deficits caused by soman intoxication.

Animals↗
PubMed2006

Diagnostic conclusions from the EASI-derived 12-lead electrocardiogram as compared with the standard 12-lead electrocardiogram in children.

BACKGROUND: Fewer electrodes on more easily located places would facilitate electrocardiogram (ECG) recording. To investigate the possibility of simplifying ECG recording in children, we compared the diagnostic conclusions when interpreting standard versus EASI-derived 12-lead ECGs. Our hypothesis was that the variation of the interpretation of standard versus EASI-derived 12-lead ECGs was not greater than the intrareader variation of the interpretation of standard ECGs. METHODS: The study included 221 children. The 2 lead systems were recorded simultaneously. Two experienced pediatric cardiologists interpreted the ECGs. First, the reader interpreted a set of 221 ECGs with randomly allocated standard and EASI-derived 12-lead ECGs. Next, the reader interpreted the complementary ECG set without having access to the first set. Finally, the reader reinterpreted the standard ECGs from 98 children. RESULTS: The variation of the interpretation of standard versus EASI-derived 12-lead ECGs was only slightly larger than the intrareader variation of the interpretation of standard ECGs. CONCLUSIONS: For most of the electrocardiographic diagnoses, the conclusions from EASI-derived 12-lead ECGs were similar to those from standard ECGs. These findings support the suggestion that the EASI lead system is a potential alternative to the standard ECG in children.

Adolescent↗
PubMed2006

[Quality standards for medical laboratories].

In France, medical laboratories must engage a quality approach according to the standard guide de bonne exécution des analyses (GBEA) and, for hospital laboratories, according to the Agence nationale d'évaluation en santé (Anaes). Except the GBEA and the Anaes handbook, which are obligatory standards by regulations, the biologists can choose, for a complementary and voluntary quality process, between the standards ISO 9001, ISO 17025 or ISO 15189. Our aim is to shed light on the advantages of these five standards by realizing a comparative study of their requirements. This work enabled us to highlight a great number of similarities and to raise the characteristics of these five standards. According to their objectives, the biologists will choose a recognition of their quality management system with an ISO 9001 certification or a recognition extended to the technical skills with an ISO 17025 or ISO 15189 accreditation. The contents of these last two documents are rather close and both integrate requirements of the standard ISO 9001. The standard ISO 17025 is, at first sight, rather distant from the biological analysis, requiring many efforts of adaptation, just like the ISO 9001 standard. The standard ISO 15189 seems to be well adapted but more constraining seeing the details requirements level needed. It necessitates a perfect control of the preanalytical phase, which is difficult to acquire in a clinical framework where the biological fluids are not taken by the laboratory staff.

Biology↗
PubMed2000

Comparison of long-term variability for standard and short-wavelength automated perimetry in stable glaucoma patients.

PURPOSE: To quantify and compare, on a point-by-point basis, the long-term variability of standard and short-wavelength automated perimetry in a group of stable glaucoma patients. METHODS: From a group of 53 glaucoma patients experienced in visual field testing, we identified one eye, randomly chosen, from each of 25 glaucoma patients whose condition was found to be stable, based on both standard and short-wavelength automated perimetry visual field criteria. On each of three visits during a period of up to 3 months, each patient performed one standard and one short-wavelength automated perimetry 24-2 visual field in a random order on a Humphrey visual field analyzer. The long-term variability (also referred to as test-retest variability) was defined as the SD of the three threshold decibel values at each test location. The long-term variability for each test point (mean +/- SD) was determined separately for both standard visual fields and short-wavelength automated perimetry. RESULTS: With all 52 test locations of the 24-2 field averaged, the global long-term variability, mean (+/- SD) for standard visual fields and short-wavelength automated perimetry was 2.37 +/- 2.03 dB (95% confidence interval, 2.26-2.48 dB) and 2.92 +/- 2.03 dB (95% confidence interval, 2.81-3.03 dB), respectively (P <.0001). In 16 of the 52 visual field locations, long-term variability on short-wavelength automated perimetry was significantly higher than long-term variability on standard visual fields. In addition, the long-term variability increased with greater distance from the point of fixation for both standard visual fields and short-wavelength automated perimetry. The long-term variability decreased closer to fixation, more for standard visual fields than for short-wavelength automated perimetry. CONCLUSIONS: In a group of stable glaucoma patients, mean long-term variability was 0.55 dB higher for short-wavelength automated perimetry than for standard visual fields. This needs to be taken into consideration when serial visual fields are evaluated for change.

Adult↗
PubMed2001

International standards in laboratory medicine.

International standards play an important role in establishing quality systems. A considerable number of standards have been created by ISO and CEN for medical laboratories. Standards can be looked upon in a hierarchal manner but most standards are produced in similarly with iterative consultations and review by the intended users. Most standards are suggested by industry and national or international organisations whereas individuals rarely can influence the contents. An exception is illustrated by a conference arranged to influence and improve the suggested standard (ISO 15196) on quality specifications in laboratory medicine. Standards may also influence the methodological practice and the performance of reagents and kits used in analytical work. A good example is the standard on traceability of calibrators (ISO 17511) that illustrates the practical importance of concepts like 'uncertainty in measurements' and 'trueness'. Biological calibrators, e.g., 'WHO biological standards', constitute a special problem since they often cannot be traced to SI. A reference procedure should be defined and referred. This would be more advantageous than to refer to a reference material that can only be traced to a master preparation. This would reduce the uncertainty and guarantee that calibrators of different batches meet certain metrological criteria.

Clinical Chemistry Tests↗
PubMed1999

International harmonization of standards for diagnostic tests and vaccines: role of the Office International des Epizooties (OIE).

The OIE is recognized as the world organization for animal health. Serving 145 member countries, the OIE provides current information on disease occurrence, coordinates studies on disease surveillance and control, and harmonizes regulations for trade in animals and animal products. This paper focuses on the role of one the OIE's specialist commissions, the Standards Commission. The Standards Commission works in close collaboration with the Scientific and Technical Department of the OIE's Central Bureau on the international harmonization of standards for diagnostic tests and vaccines. The Manual of Standards for Diagnostic Tests and Vaccines, approved by the International Committee, defines the international standards for diagnostic tests and for the production of biological products as applied to mammals, birds, and bees. The Manual lists and details those tests which are prescribed for international trade and others which are suitable for bilateral trade agreements. The Manual represents one of the key scientific and technical references for harmonization of regulations for trade in animals and animal products. The commission coordinates the activities of a network of some 110 OIE reference laboratories and six collaborating centers. By creating and nurturing this network, international harmonization is promoted through the sharing of knowledge and the establishment of collaborative projects related to methods development and standardization, production and distribution of international reference standards, quality assurance, and assay validation. Through a series of guidelines provided to participants, the commission ensures the quality and focus of these projects. In matters of a scientific and technical nature concerning diagnostic tests and vaccines, the Standards Commission collaborates with other international organizations such as the FAO, WHO, IICA, and PAHO, thus promoting harmonization at the international program level. Underscoring the important role of the OIE at this level, the Sanitary and Phytosanitary Agreement of the World Trade Organization, as included in the Marrakech agreement (1994), specifically recommends the use of standards, guidelines, and recommendations developed under the auspices of the OIE in order to promote harmonization of regulations for trade in animals and animal products.

Animal Diseases↗