危险因素在临床诊断中的应用

THE USE OF RISK FACTORS FOR DIAGNOSIS OF DISEASE

由经验性的引深为伦理性的应用危险因素辅助诊断在于研讨其真实性，即其灵敏度（ｓｅｎ）和特异度（ｓｐｅ），分别可借助病例对照研究２ｘ２表计算，由此又可计算比值比（ＯＲ）、推导ｓｅｎ和阳性似然比（ＬＲ＋）。ｓｐｅ对ＬＲ＋的影响显著大于ＯＲ值。危险因素的ｓｅｎ与ｓｐｅ也呈互补关系，参考暴露剂量提高诊断价值实质足增大了ｓｐｅ。ｓｅｎ和ｓｐｅ是来自样本的估计，也有它在总体中的可信区间。危险因素辅助诊断的价值还受着验前概率、两种以上危险因素联合使用、修饰因子等因素的制约。

To logically,not empirically use the risk factors for theassistance in the diagnosis of diseases rclies on the study ofthe validity in respect of risk factors,1.e its sensitivity(sen)and specificity (spe).By the aid of the tabled 2x2from case- control study ,the sen and Spe can be estimated. Thus sen and positive likelihood(LR+ )can be also in-ferred. The influence of spe on LR+ iS more remarkblethan that of OR, if spe was less than 50 precent, OR doesnot distinctly influence on LR+ evcn though OR is increasedto 100. There is a compensatve relationship between senand spc,When two risk factors are used as narallel or seriesconnection, the sen or spe will bc promoted.The rising ofthe diagnosis value with increasing the dose of cxposure infact expends the spc of risk factor.The confidence intervalof sen and spe must be estimated in population sincc it is de-rived from the sample,The prior disease probability influ-ences the utility of risk factors in diagnosis of discase bymeans of Bayes'theorem,In addition.it is also influencedby the modification factor.