Browsing by Author "Meijer, Piet"
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- AEQ na quantificação da hemoglobina: desempenho analítico a longo prazo de trinta laboratórios portuguesesPublication . Miranda, Armandina; Correia, Helena; Cardoso, Ana; Brito, Cristina; Clemente, Vera; Silva, Susana; Meijer, Piet; Faria, AnaÉ importante para os laboratórios clínicos avaliarem o desempenho dos seus métodos ao longo do tempo. O principal objetivo deste estudo foi a aplicação de um modelo de regressão linear para avaliação a longo prazo, do desempenho dos laboratórios na quantificação da hemoglobina, comparando os resultados individuais do laboratório com a média de consenso de cada ensaio, após a exclusão de outliers. Para avaliar o desempenho do laboratório foram calculados o coeficiente de variação analítico a longo prazo (LCVa) e o Bias total analítico. O modelo de regressão linear foi aplicado aos resultados quantitativos da hemoglobina para avaliar o desempenho analítico a longo prazo de trinta laboratórios que participam no programa de avaliação externa da qualidade PNAEQ (2014-2016), utilizando os resultados de doze amostras controlo de sangue em EDTA, com diferentes concentrações de hemoglobina. Os participantes foram selecionados aleatoriamente, sendo incluídos laboratórios hospitalares e ambulatórios. As variáveis introduzidas para avaliar o desempenho a longo prazo neste modelo foram o CV analítico a longo prazo (LCVa) e o Bias total analítico. Dois laboratórios foram excluídos da análise. Foi determinado o número de laboratórios que cumpriram os objetivos de desempenho analítico definido com base na variação biológica. A mediana do LCVa foi de 1,4% (variação de 0,4% -3,4%). O LCVa foi 0,58 vezes inferior à variação biológica total (teste de diagnóstico) para todos os laboratórios (100%) e foi 0,5 vezes inferior à variação biológica intraindividual (teste de monitorização) em 62% dos laboratórios. A mediana do Bias total foi de 1,1% (variação de 0,1% -3,3%), sendo que 83% dos laboratórios apresentaram um Bias total inferior a 0,25 da variação biológica total. A participação em programas de avaliação externa da qualidade é de extrema importância, uma vez que fornece informações ao laboratório sobre o desempenho do seu método tanto numa única análise, bem como ao longo do tempo e permite a avaliação da necessidade de melhoria.
- Avaliação Externa da Qualidade da HBA1C- Desempenho Analítico a Longo Termo e Métrica Sigma de Vinte e Um Laboratórios PortuguesesPublication . Miranda, Armandina; Pereira, Susana Pereira; Reguengos, João; Requeijo, José; Correia, Helena; Cardoso, Ana; Meijer, Piet; Faria, Ana PaulaA hemoglobina glicada (HbA1c) tem um papel crucial na monitorização e diagnóstico da diabetes. Em Portugal 9,8% da população tem diabetes (HbA1c ≥ 6,5% ou faz terapêutica para diminuição dos níveis de glicémia). A métrica Seis Sigma combina o bias, a precisão e o erro total admissível (Eta), e pode ser utilizada para avaliar a qualidade da fase analítica. O principal objetivo deste estudo foi aplicar um modelo de regressão linear para avaliar a exatidão e a precisão a longo termo e aplicar a métrica Sigma na avaliação do desempenho dos laboratórios relativamente à quantificação da HbA1c2.
- EQA quantification HbA1c Diabetes – Long-term and SIGMA analytical performance for Twenty one Portuguese LaboratoriesPublication . Miranda, Armandina; Silva, Susana Pereira; Reguengos, João; Requeijo, José; Correia, Helena; Cardoso, Ana; Meijer, Piet; Faria, Ana PaulaGlycated hemoglobin (HbA1c) plays a crucial role in the monitoring and diagnosis of diabetes. In Portugal 9,8% of the population has diabetes (HbA1c ≥ 6,5% or treatment with glucose-lowering medications)1. Six sigma metrics combine bias, precision, and allowable total error (Tea), and can be used for assessing the quality of the analytic phase. The main objective of this study was to apply a linear regression model for long-term evaluation of the precision and inaccuracy, and apply the sigma metric to evaluate the performance of laboratories in HbA1c quantification2.
- EQA quantification HbA1c Diabetes– Long-term and SIGMA analytical performance for Twenty one Portuguese LaboratoriesPublication . Miranda, Armandina; Silva, Susana Pereira; Reguengos, João; Requeijo, José; Correia, Helena; Cardoso, Ana; Meijer, Piet; Faria, Ana PaulaGlycated hemoglobin (HbA1c) plays a crucial role in the monitoring and diagnosis of diabetes. In Portugal 9,8% of the population has diabetes (HbA1c ≥ 6,5% or treatment with glucose-lowering medications). Six sigma metrics combine bias, precision, and allowable total error (Tea), and can be used for assessing the quality of the analytic phase. The main objective of this study was to apply a linear regression model for long-term evaluation of the precision and inaccuracy, and apply the sigma metric to evaluate the performance of laboratories in HbA1c quantification.
- EQA total haemoglobine quantification: long-term analytical performance for thirty Portuguese LaboratoriesPublication . Miranda, Armandina; Correia, Helena; Cardoso, Ana; Brito, Cristina; Clemente, Vera; Silva, Susana Pereira; Meijer, Piet; Faria, Ana PaulaTotal haemoglobin is one of the most frequently ordered laboratory tests, both in the hospital and ambulatory. Haemoglobin concentration provides information about the status of anaemia in the population and guides many clinical diagnoses and therapeutic interventions. Portuguese External Quality Evaluation Program (PNAEQ) provides 4 survey per year with 2 samples each since it is important for medical laboratories to know about the stability and performance of their methods over the time. The main objective of this study was to apply a linear regression model for long-term evaluation of the performance of laboratories in haemoglobin quantification by comparing the laboratory individual results with the consensus mean of each round, after outliers exclusion. To evaluate the performance of the laboratory, the long-term analytical CV (LCVa) and the total analytical bias were established.
- Evaluation of quality control viral load HIV results from two laboratories in Maputo, after the 3rd Congress of Laboratory Quality Control for Portuguese-Speaking Countries, MozambiquePublication . Faria, Ana Paula; Miranda, Armandina; Aguiar, Carmen; Sidume, Zita; Manguene, Yolanda; Vubil, Adolfo; Mabunda, Ana Flora; Manhumane, Isabel; Meijer, PietThe Project of Laboratory Quality Improvement for Portuguese Speaking Countries (ProMeQuaLab) is based on three major work tools: education, training and monitoring of quality control measures, in order to build capacity to implement and sustain good laboratory practices. Since 2015, a biennial congress on quality control is organised which includes also courses in this field. The third edition of the Congress was held in Mozambique in May 2019. Theoretical and practical courses concerning internal (CQI) and external quality control (EQA), calculation of Total Error (TE) and Measurement Uncertainty (MU) were held. Two practical work sessions were organized, with the trainers of the quality control courses and trainees from two laboratories, Centro Criança Dream (Dream) and Laboratório de Virologia Molecular (INS) in Maputo (Mozambique), to applied the statistical tools to evaluate their quality control results of viral load HIV from 2018. Evaluation of viral load is strongly recommended by WHO for monitoring response to retroviral treatment. The objective of this work was the implementation of the concepts and tools of the assessment of bias and uncertainty presented in the quality control courses and their application on the quantitative quality control results from 2018 of RNA viral load HIV-1 from two laboratories from Maputo. The concepts and tools presented in quality control courses were applied to quality control results of two laboratories in Maputo (Mozambique) for the measure of imprecision, bias and measurement uncertainty. The courses and the work sessions have proved to be very effective in transferring knowledge and skills and therefore should be continued with other laboratories. The results of the bias and measurement uncertainty show that the INS laboratory (Cobas Ampliprep TaqMan96) had a better performance in comparison to the Dream laboratory (Abbott m2000). Effort must be made to continue the education program, namely the interpretation of the quality control results to achieve an improvement of the evaluation of patient results.
- International Normalized Ratio (INR): Performance of External Quality Assessment 2016 results - PNAEQ and ECAT FoundationPublication . Correia, Helena; Silva, Susana Pereira; Miranda, Armandina; Reguengos, João; Cardoso, Ana; Brito, Cristina; Clemente, Vera; Faria, Ana Paula; Meijer, PietThe International Normalized Ration (INR) is derived from the measurement of the Prothrombin Time (PT) and the International Sensitivity Index (ISI), and is a quantitative measure of the responsiveness of individual thromboplastin reagents to the different clotting factors involved in the PT measurement. Under the INR system, all results are standardized. For example, a person taking an oral anticoagulant (ex. Coumadin) would need regularly to have a blood test to measure the INR. The INR permits patients on anticoagulants to travel and obtain comparable test results wherever they are. So it is very important to verify the laboratories performance over this test. In 2014 the Portuguese National External Quality Assessment Program (PNAEQ) has established a consortium with ECAT Foundation for INR measurement where Portuguese laboratories are included in the statistical analysis. The main objective of this study was to evaluate the performance for INR of PNAEQ participants that used two different thromboplastin reagents during 2016 and compared those with the results of ECAT participants.
- Interpretação dos resultados de Avaliação Externa da QualidadePublication . Faria, Ana Paula; Meijer, Piet; Wahlstedt, Juha; Pereia, PauloAgenda: 1- Interpretation of performance reports with case studies (Flowchart) - Piet Meijer, Director da ECAT Foundation 2- Labquality reports interpretation - Juha Wahlstedt, EQA Solution Specialist da Labquality Oy 3- Cálculo de Incertezas - Paulo Pereira, investigador do IPST
- Is D-dimer used according to clinical algorithms in the diagnostic work-up of patients with suspicion of venous thromboembolism? A study in six European countriesPublication . Kristoffersen, Ann Helen; Ajzner, Eva; Rogic, Dunja; Sozmen, Eser Y.; Carraro, Paolo; Faria, Ana Paula; Watine, Joseph; Meijer, Piet; Sandberg, Sverre; joint Working Group on Postanalytical Phase (WG-POST) of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) and European Organisation for External Quality Assurance Providers in Laboratory Medicine (EQALM).Introduction: Clinical algorithms consisting of pre-test probability estimation and D-dimer testing are recommended in diagnostic work-up for suspected venous thromboembolism (VTE). The aim of this study was to explore how physicians working in emergency departments investigated patients suspected to have VTE. Materials and methods: A questionnaire with two case histories related to the diagnosis of suspected pulmonary embolism (PE) (Case A) and deep venous thrombosis (DVT) (Case B) were sent to physicians in six European countries. The physicians were asked to estimate pre-test probability of VTE, and indicate their clinical actions. Results: In total, 487 physicians were included. Sixty percent assessed pre-test probability of PE to be high in Case A, but 7% would still request only D-dimer and 11% would exclude PE if D-dimer was negative, which could be hazardous. Besides imaging, a D-dimer test was requested by 41%, which is a “waste of resources” (extra costs and efforts, no clinical benefit). For Case B, 92% assessed pre-test probability of DVT to be low. Correctly, only D-dimer was requested by 66% of the physicians, while 26% requested imaging, alone or in addition to D-dimer, which is a “waste of resources”. Conclusions: These results should encourage scientific societies to improve the dissemination and knowledge of the current recommendations for the diagnosis of VTE.
- Pre- and post-test probabilities of venous thromboembolism and diagnostic accuracy of D-dimer, estimated by European clinicians working in emergency departmentsPublication . Kristoffersen, Ann Helen; Ajzner, Eva; Bauça, Josep Miquel; Carraro, Paolo; Faria, Ana Paula; Hillarp, Andreas; Rogic, Dunja; Sozmen, Eser Y.; Watine, Joseph; Meijer, Piet; Sandberg, SverreIntroduction: In patients with suspected venous thromboembolism (VTE), it is recommended to estimate the pre-test probability of VTE, either by experience or by standardized scoring schemes (e.g. Wells or Geneva score), before performing a D-dimer test. Patients with a low probability or unlikely VTE should have D-dimer performed, and if negative, VTE can be excluded, without further investigations, while if positive, the patient should be referred to radiologic imaging to confirm or exclude VTE. Patients with a high pre-test probability or likely VTE should be referred directly to radiologic imaging without D-dimer testing. Thus, to estimate the pre-test probability of VTE before D-dimer testing is of uttermost importance since the diagnostic algorithm and the interpretation of the D-dimer result is dependent upon this. Further, the diagnostic accuracy of D-dimer can be expressed by the likelihood ratio (LR). LR is the ratio between the probability of a test result given that VTE is present, and probability of the same test result if VTE is absent. A LR of< 1 decreases the probability of disease and a LR of> 1 increases the probability of disease. When clinicians estimate the pre-test probability for VTE, the post-test probability (after D-dimer testing) can be calculated using the LR for D-dimer either for a positive or negative test (i.e. D-dimer above or below the cut-off level, respectively). Probably, most clinicians do not know the LR for D-dimer, but it is indirectly implemented in the above mentioned algorithm for investigating a patient with suspected VTE. The advice to rule out VTE in a patient if the pre-test probability of VTE is low and the D-dimer is below the cut-off level reflects that the post-test probability of VTE in this case is sufficiently low to rule out VTE (should be< 1-2%). However, if the pre-test probability of VTE is high or likely, a negative D-dimer cannot decrease the post-test probability enough to rule out VTE (the post-test probability will still be about 10%) [4,5]. Therefore, only imaging should be requested when pre-test probability of VTE is high. A positive D-dimer cannot increase post-test probability of VTE enough to confirm VTE diagnosis in any case, since D-dimer is a non-specific VTE marker and levels can be increased in several other clinical situations (e.g. infection, inflammation, cancer and pregnancy). The aims of this survey were 1) to study the relationship between pre-test probabilities estimated by clinicians using two case histories and how the same clinicians' categorized the patients into low, moderate or high probability of VTE or into unlikely or likely VTE, and 2) to examine the clinicians' perception of diagnostic accuracy of D-dimer by calculating the LRs based upon their estimated pre- and post-test probabilities.