Desbiens N A, Turney S L, Gani K S
Department of Medicine, Marshfield Clinic, WI 54449.
J Lab Clin Med. 1990 Mar;115(3):292-7.
Current teaching concerning the frequency of abnormal results secondary to chance alone in a multichannel panel is theoretically based on the binomial distribution. However, this distribution can be used only when the probability of an abnormal result (pi) is the same for each test in the panel. In modern-day multichannel testing, pi varies from test to test and most often is less than the usually reported 0.05. On the other hand, a test such as cholesterol may have a pi level as high as 0.55. Theoretically the only distribution that can take this variability into consideration is the Lexis distribution, a form of the binomial distribution that allows for varying pi s. Since no formula is available to calculate this distribution, we wrote a computer program to generate it. We arranged 18-test panels from 203 normal patients in a frequency distribution. This was then compared with the theoretical Lexis and binomial distributions. This analysis showed that although there was a 50% chance of having one abnormality per panel and a 16% chance of having two abnormalities per panel, there was less than 4% chance of having three or more abnormalities per 18-test panel. In addition, most of the abnormalities noted were minor and were thought to be clinically unimportant.
当前关于多通道检测中仅因偶然因素导致异常结果出现频率的教学内容，在理论上是基于二项分布的。然而，只有当检测面板中每项检测出现异常结果的概率（pi）相同时，才能使用这种分布。在现代多通道检测中，每项检测的pi值各不相同，且多数情况下小于通常报告的0.05。另一方面，像胆固醇检测这样的项目，其pi值可能高达0.55。从理论上讲，唯一能考虑到这种变异性的分布是莱克西斯分布，它是二项分布的一种形式，允许pi值有所变化。由于没有可用于计算这种分布的公式，我们编写了一个计算机程序来生成它。我们将203名正常患者的18项检测面板结果整理成频率分布。然后将其与理论上的莱克西斯分布和二项分布进行比较。该分析表明，虽然每个检测面板出现一次异常的概率为50%，出现两次异常的概率为16%，但对于18项检测的面板，出现三次或更多次异常的概率不到4%。此外，所发现的大多数异常情况都较为轻微，被认为在临床上无足轻重。
