Abstract
童峰,陈坤,何寒青.需暴露人数在流行病学中的应用[J].Chinese journal of Epidemiology,2005,26(7):540-543
需暴露人数在流行病学中的应用
Concept on the use of "number needed to be exposed" in epidemiology
Received:January 08, 2005  
DOI:
KeyWord: 需暴露人数  流行病学  前瞻性研究
English Key Word: Number needed to be exposed  Epidemiology  Prospective studies
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Author NameAffiliationE-mail
TONG Feng Department of Epidemiology and Health Statistics, School of Medicine, Zhejiang University, Hangzhou 310031, China  
CHEN Kun Department of Epidemiology and Health Statistics, School of Medicine, Zhejiang University, Hangzhou 310031, China ck@zju.edu.cn 
HE Han-qing Department of Epidemiology and Health Statistics, School of Medicine, Zhejiang University, Hangzhou 310031, China  
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Abstract:
      目的介绍需暴露人数(NNE)的基本概念、计算方法及用途。方法以琥珀水杨酸交联血红蛋白溶液(DCLHb)治疗急性创伤后出血性休克与患者入院后28天内死亡的研究为实例,计算粗NNE和调整NNE及相应95%可信区间(CI)。结果通过计算得到暴露DCLHb的粗NNEH=3.7(95%CI:2.2~11.5);在调整了基线死亡风险的混杂偏倚后,暴露DCLHb的调整NNEH=2.6(95%CI:1.6~8.0)。说明在试验组研究对象的基线死亡风险(病情严重程度)的分布与对照组相同的情况下,平均每2.6例创伤后出血性休克患者暴露于DCLHb就会在入院后28天内新增1例死亡。结论NNE可用来说明在前瞻性研究中,相对于非暴露组,要新增(或预防)一例某病的发病或死亡病例,需暴露于某因素的平均估计人数。作为衡量暴露因素作用强度的一个新指标,NNE可以更为直观地表达研究的结果,易被临床医生、卫生决策者及公众所接受。
English Abstract:
      Objective To introduce the concept, methods for calculation and application of "number needs to be exposed(NNE)" in Epidemiological studies. Methods Data was analyzed from a study on the association between diaspirin cross linked hemoglobin(DCLHb) with 28-day mortality in patients with severe traumatic hemorrhagic shock. Results The crude "number needed to be exposed for one additional person to be harmed" (NNEH) was 3.7(95%CI: 2.2-11.5) for the exposure to DCLHb. After controlling the confounding bias of the baseline mortality risk, the adjusted NNEH became 2.6(95%CI: 1.6-8.0) id. , on average, among 2.6 patients exposed to DCLHb, one additional case of death would have developed within 28 days after initial hospitalization if the distribution of baseline mortality risk in exposed group had been equal to that in the unexposed group. Conclusion NNE could be expressed as the estimated average number of persons needed to be exposed for contributing(either developing or preventing for) one additional case of disease or death in a prospective study when compared with the unexposed persons. As a new index for measuring the absolute effect of an exposure, NNE presented the results on epidemiological studies in a more intuitive and understandable manner. Consequently, this method could be favorably accepted by clinicians, health policy makers and the public.
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