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PubMed2001

Quality control including validation in dietary surveys of elderly subjects. The validation of a dietary history method (the SENECA-method) used in the 1914-population study in Glostrup of Danish men and women aged 80 years.

BACKGROUND: Quality control including validation in dietary surveys is needed to reduce and detect errors which would lead to an attenuated scientific foundation for the diet-disease relationship. Especially studies in the elderly are needed because of limited knowledge of reference values, cut-off values etc. OBJECTIVE: To validate a modified dietary history method (the SENECA-method) in elderly subjects. DESIGN: A survey of Danish men and women aged 80 years, who participated in the 1914-population study in Glostrup. SUBJECTS AND METHOD: A pilot study (n = 34) validated the dietary history against 24-h urine collections; a main study (n = 240) compared dietary history with a 3-day estimated food record. RESULTS: Protein intake from dietary history was 10% higher than calculated protein intake from 24-h urine collections. Differences in intakes of energy and macronutrients between dietary history and 3-day food record were generally small and non-significant, and there was good agreement between the methods in classifying nutrient intakes into same tertiles. A Bland & Altman plot indicated increasing differences in energy intake between methods with increased energy intake. Evidence for under-reporting of energy intake and/or over-reporting of the physical activity level was further made plausible when physical activity ratio was compared to recognized cut-off limits. CONCLUSIONS: The modified dietary history method can be used to estimate dietary intake in 80 year old subjects, but some degree of misreporting, especially under-reporting, appears to be present. Keeping this in mind it is, however, possible to analyse dietary intake against other survey data.

Aged↗

PubMed2000

Efficacy, safety, quality control, marketing and regulatory guidelines for herbal medicines (phytotherapeutic agents).

This review highlights the current advances in knowledge about the safety, efficacy, quality control, marketing and regulatory aspects of botanical medicines. Phytotherapeutic agents are standardized herbal preparations consisting of complex mixtures of one or more plants which contain as active ingredients plant parts or plant material in the crude or processed state. A marked growth in the worldwide phytotherapeutic market has occurred over the last 15 years. For the European and USA markets alone, this will reach about $7 billion and $5 billion per annum, respectively, in 1999, and has thus attracted the interest of most large pharmaceutical companies. Insufficient data exist for most plants to guarantee their quality, efficacy and safety. The idea that herbal drugs are safe and free from side effects is false. Plants contain hundreds of constituents and some of them are very toxic, such as the most cytotoxic anti-cancer plant-derived drugs, digitalis and the pyrrolizidine alkaloids, etc. However, the adverse effects of phytotherapeutic agents are less frequent compared with synthetic drugs, but well-controlled clinical trials have now confirmed that such effects really exist. Several regulatory models for herbal medicines are currently available including prescription drugs, over-the-counter substances, traditional medicines and dietary supplements. Harmonization and improvement in the processes of regulation is needed, and the general tendency is to perpetuate the German Commission E experience, which combines scientific studies and traditional knowledge (monographs). Finally, the trend in the domestication, production and biotechnological studies and genetic improvement of medicinal plants, instead of the use of plants harvested in the wild, will offer great advantages, since it will be possible to obtain uniform and high quality raw materials which are fundamental to the efficacy and safety of herbal drugs.

Controlled Clinical Trials as Topic↗

PubMed2002

Terminal digit preference and single-number preference in the Syst-Eur trial: influence of quality control.

BACKGROUND: Terminal digit and single-number preference may produce inaccuracy and biased results when measuring blood pressure. We describe these preferences in the Syst-Eur randomized placebo-controlled trial of the treatment of isolated systolic hypertension and describe how we sought to eliminate these problems. METHODS: The Data Monitoring Committee of the trial conducted yearly quality control meetings in Belgium and visited the participating centres to check their adherence to the protocol. These meetings involved identifying terminal digit preference, improving blood pressure control and boosting recruitment. RESULTS: The prevalence of use of terminal digit zero when measuring sitting systolic blood pressure (first readings) reduced from an average of 42.4% in the year prior to the date when a centre first randomized a patient to 31.5, 25, 22.3, 26.3, 23.2 and 22% in the subsequent 6 years. This trend was independent of the calendar year during which a centre entered the trial and supports the hypothesis that data-quality monitoring, including the feedback of digit preference to centres, led to a reduction in terminal digit zero preference. In addition, a higher than expected prevalence of the systolic blood pressure value of 148 mmHg was found in the active treatment groups in the double-blind phase. Selection for 148 mmHg persisted over time and constituted a single-number preference bias. This arose from the instruction to investigators to reduce systolic blood pressure to below 150 mmHg. CONCLUSION: Monitoring and feedback of data quality should be undertaken to minimize digit and number preference. Automatic devices should ideally be employed to help to avoid these problems as long as the devices are fully validated and regularly serviced, and providing that readings are not rejected and repeated.

Bias↗

PubMed1995

[Can we rely on Norwegian surgery data? A quality control at central and local hospitals of the procedure codes used in the survey on organization of gastrointestinal cancer surgery].

The nation-wide register of hospital discharges in Norway includes ICD-9 and national procedure codes. Hospitals were asked to check five surgical procedures listed in the register against the primary data sources. 649 discharges were controlled. The response rate was 68%. The results indicate that the quality of the data in the register varies for the different procedures. For procedures with high volume (resection of rectum), the error in the register is 3%. This is the same as reported from other Nordic countries. The proportion of errors in the register was high in hospitals with only one registered procedure code. The quality of data can to some extent be checked on the basis of DRG coding (DRG group 468/477). Quality control of register data is required when the number in DRG 468/477 is high in the nation-wide register or when the number of specific procedures in hospitals is low.

Databases, Factual↗

PubMed1984

[Quality control of radioimmunoassay by bivariate analysis].

Automatic calculation of control charts for precision and accuracy of radioimmunoassay was reported by Faure, et al. Duplicate control samples independently measured was assumed to have a bivariate normal distribution. In this case they assumed that the correlation coefficient between each value of the pairs of control samples is zero. Our experience using this method revealed that a considerable number of assayed samples distributed outside the calculated control limits in case of "accuracy control". It was considered that this happened because in radioimmunoassay the between-assays precision is usually larger than the within-an-assay precision and there is a significant correlation between values of duplicates. We also found equal probability density did not make a true circle but a long circle. Therefore in the present paper we proposed for control charts of radioimmunoassay an equal probability long circle calculated by bivariate analysis of Mahalanobis' generalized distance. It was found that a Mahalanobis' long circle could explain the density distribution of radioimmunoassay with a reasonable percent of samples outside the calculated control limits. What happened here can be interpreted by a large between-assays variability shown by some commercial kits. This automatic calculation method could be applied not only for quality control but also for evaluation and comparison of radioimmunoassay system or commercial kits. Control survey could also be analyzed by such a method.

Analysis of Variance↗

PubMed1975

Quality control in hematology by means of values from patients.

The results of the analyses which were obtained with the Hemalog for the determination of platelets, white blood cells, red blood cells, hemoglobin and hematocrit were statistically analysed for the quality control of the determinations. Now that the testing method has been applied for 6 months, it appears from the results that it is extremely suitable for the determination of hemoglobin, red blood cells and the hematocrit and, to a lesser extent, for white blood cells and platelets.

Autoanalysis↗

PubMed1975

Notes on the organization of tuberculosis bacteriology and its quality control.

The time-scale of tuberculosis allows the centralization of identification and sensitivity tests on positive cultures with the advantages of better efficiency, economy and safety. The system operated in England and Wales is described with its methods of quality control. The incidence of false resistance in new cases is less than 0-1 per cent and that of missed resistance little more. Arguments are advanced against the use of blind chemotherapy on new patients in Britain.

Aminosalicylic Acids↗

PubMed1997

The AutoPap 300 QC System multicenter clinical trials for use in quality control rescreening of cervical smears: II. Prospective and archival sensitivity studies.

BACKGROUND: The AutoPap 300 QC System is an automated device for the analysis of conventional cervical cytology slides. The AutoPap selects an enriched population of cases for quality control review. These studies evaluated the overall sensitivity of AutoPap device to a wider variety of cytologic abnormalities than could be analyzed in the prospective portion of the clinical trials. METHODS: At five clinical trial sites, positive cases were selected from: 1) archives (historic sensitivity study) or 2) current positive cases (current archive sensitivity study). Cases were analyzed by the AutoPap System along with matched negative cases and stratified into detection deciles by instrument score for each diagnostic category. RESULTS: For the historic sensitivity study, the percentages of cases present within the top 10% instrument scores were as follows: atypical glandular cells of undetermined significance (AGUS): 33.7% (n = 243); low grade squamous intraepithelial lesion (LSIL): 57% (n = 412); high grade squamous intraepithelial lesion (HSIL): 81.6% (n = 385); and carcinoma: 77.7% (n = 139). For the current archive sensitivity study, the percentage of cases within the top 10% of instrument scores were as follows: atypical squamous cells of undetermined significance (ASCUS): 37.6% (n = 205); AGUS: 27.3% (n = 22); LSIL: 53.7% (n = 410); HSIL: 80.7% (n = 202); and carcinoma: 62.5% (n = 8). Sensitivities at higher percentiles proportionately were greater. CONCLUSIONS: The AutoPap 300 QC System is detection sensitive, particularly at the level of LSIL and greater. When coupled with the data from the prospective intended use study, these results provided confirmation of the instrument's ability to enhance the false-negative detection rate significantly when compared with a 10% random case selection process. In addition, high sensitivities to all categories of abnormality suggest the possibility of using such instrumentation as a primary screening device for cervical cytology.

Automation↗

PubMed1985

Assessment of a bubble tonometer as a quality control system for blood gas analyzers (PO2 and PCO2).

A blood gas tonometer device, comprising an accurate gas mixer (Corning 192) associated with a dual channel bubble tonometer (Corning 184) was tested for reliability, accuracy and ease of use as a quality control system for pO2 and PCO2 blood gas analyzers. From our results it is apparent that this system can be used instead of older and more bulky tonometry devices, gas mixing systems or cylinders of fixed composition.

Blood Gas Analysis↗

PubMed1995

Quality control of DXA instruments in multicenter trials.

Dual-energy X-ray absorptiometry (DXA) has become the measurement of choice for multicenter trials with bone density endpoints. When performing DXA measurements with several different systems, it is important to implement a quality assurance program to guarantee that any observed density changes are real and not due to machine and/or operator variability. In this study, we present a series of procedures based on phantom measurements designed to monitor DXA instrument stability. Techniques for longitudinal evaluation of machine performance and cross-calibration of instruments are described. These procedures are then demonstrated using quality assurance data collected from a number of different DXA scanners. Together these methods provide a defined approach to instrument quality control. Though based primarily on the use of spinal phantoms, these procedures can be generalized for use in any multicenter DXA study.

Absorptiometry, Photon↗

PubMed1987

Quality control issues in modern cataract surgery.

Modern extracapsular cataract surgery is considerably more complex than the previous intracapsular procedure. Intraocular manipulations are required, and solutions and products must be introduced into the eye. Due to the shift to ambulatory surgery, modern cataract surgery is also being performed in a difficult and more dangerous environment. In these circumstances, sterility and product quality may be compromised when a lack of appropriate surveillance techniques leads to the use of defective products in surgery. The modern cataract surgeon must, therefore, become knowledgeable about infection and quality control procedures in the operating room, and also about details of manufacture and industrial standards applicable to the products used in eye surgery.

Cataract Extraction↗

PubMed1992

[The quality of biological information: standardization and quality control].

Some procedures and methods for the measurement of cardiovascular risk factor are described; in particular of anthropometric measurements (weight, height, arm circumference, wrist circumference, hip circumference) of blood pressure, of electrocardiogram and of blood samples for the preservation of biological specimens. Some advice for the quality control during screening activities are reported.

Anthropometry↗

PubMed1989

Impact of initial quality control review on study outcome in lung and head/neck cancer studies--review of the Radiation Therapy Oncology Group experience.

The Radiation Therapy Oncology Group (RTOG) initiated cooperative clinical trials in 1971. In 1978, RTOG developed a formalized program of Quality Control (QC) divided into initial and final phases. The initial review process consisted of two steps. The first phase of review is an evaluation performed by a radiation oncologist to verify treatment plan and field borders. The second portion of the initial review process originally consisted of dosimetry calculation verification based on machine data provided by the regional Radiological Physics Center and treatment planning data provided by the accessioning institution. Between 1978 and December 31, 1987, a total of 11,343 cases in 96 RTOG protocols, excluding particle studies, underwent initial review. Of this number, 2227 patients were entered in lung cancer studies and 1341 patients were entered in head/neck cancer studies. Initial review was carried out in 2089 (93.8%) of the lung cancer cases. Missing or delayed data accounted for 138 (6.2%) cases not reviewed initially. In head/neck cancer trials, 1251 (93.2%) received initial review and 90 (6.8%) did not. Our findings suggest that there are sharply defined but long lasting learning experiences involved in clinical trial participation. Consideration may be given to modifying the initial review process to use random sampling of cases accessioned by experienced investigators in ongoing clinical trials and to continuing the total case evaluation on all new studies and cases entered by inexperienced investigators or investigators/institutions with unsatisfactory performance. Recommendations regarding initial review of other sites will await evaluation of the impact of initial review on those sites.

Head and Neck Neoplasms↗

PubMed1993

[Methods for quality control in parenteral nutrition. III: application of the program to therapeutic results].

Therapeutic results of parenteral nutrition are evaluated by clinical nutritional benefits and by its safety with respect to the potential complications related to the method of administration and its inherent metabolic complications. In this context, a quality control programme was applied retrospectively to 148 patients and was evaluated according to the following indicators: a) PN suspension; b) a nutritional evaluation on termination of the parenteral nutrition; c) catheters inserted; d) mechanical complications; e) septic complications; f) routine controls; g) complete controls, and h) biochemical changes. The compliance percentages obtained were 92.8, 100, 85.1, 81.4, 84.9, 60.0, 33.1 and 43.8 respectively. These results allow us to see, for the first time, the profile of therapeutic quality in patients with parenteral nutrition. Likewise, it constitutes an obligatory methodology of intrahospital reference for continued improvement of parenteral nutrition received by patients admitted to this hospital.

Adolescent↗

PubMed1996

Improvement of quality control for steroid receptor measurements: analysis of distributions in more than 40000 primary breast cancers. French Study Group on Tissue and Molecular Biopathology.

All French laboratories that routinely assay estradiol (ER) and progesterone (PR) receptors participate in the European EORTC quality control program based on twice-yearly analysis of 5 cytosolic preparations. This system has considerably reduced inter-laboratory variations, but does not cover all aspects of these assays. Analysis of receptor value distributions is also crucial to ensure that receptor measurements remain stable with time, independently of the laboratory and assay method. This study involved 83907 receptor assays carried out in the last 17 years by 17 laboratories belonging to the French Study Group on Tissue and Molecular Biopathology. The assays were based on radioligand binding (RLA) or immunoenzymology (EIA). For each laboratory, the medians and positivity rates were analysed according to two totally objective criteria, the patient's age and the year of assay, and according to histological grade and histological type of the tumor in order to verify the correlations classically described. Age-related distributions varied little between laboratories, compared with data published by 7 European EORTC laboratories [1]. The results remained relatively stable with time in the RLA method for ER and PR, and in the EIA method for PR. Median ER-EIA data showed a marked increase between 1987 and 1989, mainly due to changes in the quality of Abbott reagents during this period. Otherwise, this analysis confirms previous pathophysiological observations.

Adult↗

PubMedDate not supplied

The PAPNET system for quality control of cervical smears: validation and limits.

The Pap-test may fail to identify false negative cases. Probably only full rescreening assisted by instrument can prevent potential screening and interpretation errors. Therefore, the PAPNET System was used obtain accurate Quality Control (QC) of 3000 conventional cervical smears. Sixteen false negatives were detected with the rescreening assisted by PAPNET. Thirteen positive cases were suspected during evaluation assisted by the PAPNET; two cases were classified as Review for potential inflammatory cellular changes and underwent full optic microscope. In one case both primary screening and the PAPNET did not detect the only abnormal cell cluster located near the coverslip edge, being part of the slide excluded from the scanning process due to focusing problems: only coverslip edge rescreening by optic microscopy allowed the formulation of the correct conclusive diagnosis. In conclusion, the PAPNET System is useful for QC of conventional cervical smears: in fact this instrument allows the identification of false negative cytological errors easily and effectively. Nevertheless, some slide scanning program modifications are needed to detect all abnormal cells present on slide under coverslip.

Algorithms↗

PubMed2001

[Quality control of DNA testing in hereditary diseases].

The laboratories performing diagnostic studies regarding hereditary diseases and the specialists providing hereditary counselling are housed in clinical genetic centres. The laboratories are subject to the Special Medical Performances Act and have had licenses from the Ministry. The DNA diagnostic laboratories united in the National Committee on DNA Diagnostics, engaged among other things in quality control. The large number of tests requested and the dramatic consequences for the patient and his relatives necessitate high quality standards. The laboratories made a division of labour for analysis of most disorders, in order to acquire and maintain expertise in spite of rarity of most hereditary diseases. For adequate handling of requests for DNA diagnostic tests, it is important that the patient material be sent directly to the laboratory specialized in the disorders in question, for the request form to be filled out completely and for the patient data to be stated on the blood tube. A regularly updated review of the DNA diagnostics in the Netherlands can be found on the website: http://www.unimaas.nl/ approximately LOD/lod.htm. This list indications per centre and information such as required material and maximal results deadlines.

Genetic Diseases, Inborn↗

PubMed1990

Development and evaluation of a method for preservation of synovial fluid wet preparations for quality control testing of crystal identification.

We describe a technique for embedding drops of fresh synovial fluid in mounting resin to prepare test slides that retain crystal morphology for at least 2 weeks. Hospital and private rheumatologists were solicited nationwide to test themselves and their staff with 5 unknown specimens. Eighty-nine percent identified monosodium urate (MSU) crystals from a tophus but only 71% identified smaller and less frequent MSU. Seventy-five percent correctly identified calcium pyrophosphate dehydrate and 42% detected steroid crystals. Apatite crystal clumps included as control slides with no birefringent material were suspected by only 7%. This or another method which simulates actual practice by also testing the equipment and handling of the microscope is proposed as an important component of quality control testing programs for synovianalysis.

Birefringence↗