IVDT_In Vitro Diagnostics Technology

IVD Technology, Fall 2013

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MANUFACTURING Delivering Reproducibility in Quantitative LateralFlow Assays Lateral-fow assay reproducibility is not only infuenced by design and manufacturing, but also by the components used in the assembly of the test, the most critical of which is the reaction membrane. BY DR KLAUS HOCHLEITNER AND BRENDAN O'FARRELL iagnostic testing has become an essential aspect in a wide variety of settings. Testing assists in the identifcation of risk factors such as cholesterol levels for coronary disease risk. Establishing the presence of disease or condition (for example, respiratory infection, hepatitis, and myocardial infarction) would be difcult if not impossible without the aid of a diagnostic test. Diagnostic testing also can be used to diferentiate between acute and previous infection. For example, diferential analysis of an immunological response can distinguish an active infection from a latent one. Te results of a diagnostic test have a large infuence on clinical management. Diferential diagnosis such as viral versus bacterial infection can reduce the incidence of overprescribing antibiotics. Together with clinical symptoms, the detection of biomarkers such as troponin I or C-reac- D High versus low reproducibility 14 12 Value 10 8 6 4 2 0 0 1 2 3 4 5 Test Figure 1. High reproducibility (green) versus low reproducibility (red). Negative sample (triangle) and positive sample (circle). High reproducibility tests (1 and 2) show clear differentiation between negative and positive results, whereas tests 3 and 4 (low reproducibility) show less differentiation between negative and positive results. tive protein (CRP) indicates the need for prompt medical intervention. Disease management activities can also be infuenced by diagnostic test results. Monitoring of cholesterol levels allows for assessing the efcacy of cholesteremia modifying therapeutics, diet, and exercise. Assessment of thrombolytic agents plays an important role in the management of coronary artery disease (CAD). Diagnostic tests are not limited to human healthcare. Diagnostic tests are also utilized in other areas where analysis is important, ranging from agriculture to environmental testing to food safety to veterinary applications. Irrespective of the area of use and application, diagnostic tests should demonstrate cost efectiveness and clinical utility. A test that fails to demonstrate these aspects is apt to be replaced by one that does. However simple and cost efective, a test must also demonstrate adequate reproducibility to distinguish clinically relevant results from assay variability. Tere is little value and utility in a test if the lack of reproducibility casts doubt on the results. Consider the scenario where a single, positive sample and a negative sample containing no analyte are analyzed multiple times in the same assay. An assay with high reproducibility will report values in a smaller distribution than will an assay with low reproducibility. Figure 1 shows the results when testing a positive and negative sample in an assay with high and low reproducibility. Referring to Figure 1, assume the assay has a defned cut-of limit of 7.5 units. Te assay with high reproducibility allows for clear diferentiation between positive and negative results. Tis contrasts with results obtained in the assay with low reproducibility. Because of the large variation, there is reduced confdence distinguishing clinically relevant results (positive sample) from the assay variability (negative sample). I VD T EC H N O L O G Y | F A LL 2 0 1 3 1 5 magenta cyan yellow black ES323918_IV1309_015.pgs 09.24.2013 06:18 UBM

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