Galbraith L V, Leung F Y, Jablonsky G, Henderson A R
Department of Clinical Biochemistry, University Hospital, University of Western Ontario, London, Canada.
Clin Chem. 1990 Jul;36(7):1317-22.
Using receiver-operating characteristic (ROC) curve and likelihood ratio analysis, we examined the diagnostic utility of total lactate dehydrogenase (LD; EC 1.1.1.27) activity (I). LD isoenzyme-1 activity (II), and the LD-1 percentage of total LD activity (III), LD-1 LD-2 (IV), and LD-1/LD-4 (V) in 347 persons admitted to the Cardiac Care Unit (of whom 173 were subsequently proven to have had myocardial infarction). Blood was sampled from these subjects at about 6-h intervals for up to 96 h from the onset of chest pain. Defining an "effective" test as one having an area under the ROC curve of greater than or equal to 0.9, we determined the ranked utility (greatest to least) of these tests as V = IV greater than III greater than II greater than I. Tests III, IV, and V had by this criterion, diagnostic effectiveness equivalent to measurements of creatine kinase-2 in serum but in samples obtained at later time intervals. The decision thresholds for both high (constant) test sensitivity and specificity varied with time, to differing extents, over the entire 96-h period, a finding with important diagnostic implications. We document positive and negative likelihood ratio values for each of these tests throughout the entire period of study.
我们使用接受者操作特征（ROC）曲线和似然比分析，检验了总乳酸脱氢酶（LD；EC 1.1.1.27）活性（I）、LD同工酶-1活性（II）、总LD活性中LD-1的百分比（III）、LD-1/LD-2（IV）以及LD-1/LD-4（V）在347名入住心脏监护病房患者（其中173人随后被证实患有心肌梗死）中的诊断效用。从胸痛发作开始，每隔约6小时对这些受试者进行采血，最长持续96小时。将ROC曲线下面积大于或等于0.9的测试定义为“有效”测试，我们确定这些测试的效用排名（从高到低）为V = IV大于III大于II大于I。根据这一标准，测试III、IV和V的诊断有效性等同于血清中肌酸激酶-2的测量，但在较晚时间间隔采集的样本中。在整个96小时期间，高（恒定）测试敏感性和特异性的判定阈值在不同程度上随时间变化，这一发现具有重要的诊断意义。我们记录了整个研究期间这些测试各自的阳性和阴性似然比值。
