HTHSCI 1LL3 Lecture Notes - Lecture 1: False Positives And False Negatives, Sensitivity And Specificity, Muscle Contraction
11 Dec 2014
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The lab is required to have a clear and rational policy for identifying specimens, and handling misidentified specimens. Retrievable versus irretrievable: if it is retrievable (obtained again without affect on the patient) just get another one venous blood urine, it is irretrievable. The clinical performance of a laboratory test defines how well it predicts disease. The specificity of a test indicates the likelihood that it will be negative when disease is absent: if do the test on normal patients (cid:0) all turn out negative = 100% specificity. False positive (fp) normal people falling outside rr. False negative (fn) diseased individual falling inside rr. Choice of test characteristic is a function of diagnostic need: discovery tests are often applied to asymptomatic patients. Exclude diseases (rule them out) because you screen and catch it as early as possible. A test that is sensitive wont be acted upon right away: confirmatory tests require high specificity establish presence of disease.
