Paulo Pereira

By Paulo Pereira

The “Guide to the Expression of Uncertainty in Measurement” (GUM) is not systematically used in medical laboratories, for what the laboratorian should understand the Uncertainty Approach and its importance to recognize the level of realism of results. This chapter presents, discusses, and recommends the models fulfilling GUM principles. An example is given to a single test for an easier understanding of the determination of measurement uncertainty. All the practice uses a freeware. Results with larger measurement uncertainty intervals have a significant probability of being unrealistic, arising a high risk of the uncorrected clinical decision. A flow chart to the selection of models for the determination of measurement uncertainty in a medical laboratory is recommended.

Part of the book: New Trends and Developments in Metrology

By Paulo Pereira and Sandra Xavier

The decisions are critical in transfusion and transplantation principally because they could affect directly and indirectly the post‐transfusion and post‐transplantation safety. However, the blood, cells, and tissues banks should not be uniquely centered in the satisfaction of receptor (patient) requirements. All the decisions affecting the sustainability of the organization should also be considered. Despite not to be systematically used in these banks, the analytical hierarchy process could be useful for the improvement in the reliability of the decisions. This chapter reviews the basics of the analytical hierarchy process applied to the production of blood, cells, and tissues, and presents a case study that could be interpreted as applicable to other situations in these organizations.

Part of the book: Applications and Theory of Analytic Hierarchy Process

By Paulo Pereira

Rapid diagnostic tests are used for the determination of binary qualitative results not only uniquely in nonhospital-based but also in hospital-based tests. Principally, in developing countries, rapid diagnostic tests are the primary option since tests to be used in medical laboratories are discarded due to the higher cost. The test’s performance is evaluated to assure that the chance of results to be false is clinically acceptable. Therefore, the diagnostic accuracy of results (diagnostic sensitivity and specificity) is assessed to guarantee the safety of postclinical decision. The statistical approach requires that representative samplings of the populations of infected and healthy individuals are tested. The area under the receiver-operating characteristic (ROC) curve is a complementary measurement using the same samplings. It represents the diagnostic accuracy in a single outcome. When samplings with known diagnostics are unavailable, samplings with known outcomes from a comparative test are used to determine the agreement of results. However, this approach is secondary, due to diagnostic accuracy to be unmeasurable. The seronegative period is another critical measurement that allows determining an individual biological bias during a period where results of an infected individual are false-negatives due to seroconversion. The claimed requirements should be defined for diagnostic accuracy and agreement outcomes. A spreadsheet is used to estimate the results considering the absolute value and the 95% confidence interval.

Part of the book: Proof and Concepts in Rapid Diagnostic Tests and Technologies