van der Eijk Ellen A, van de Vosse Esther, Vandenbroucke Jan P, van Dissel Jaap T
Department of Infectious Diseases, C5-P, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
Am J Respir Crit Care Med. 2007 Dec 15;176(12):1281-8. doi: 10.1164/rccm.200703-435OC. Epub 2007 Sep 6.
In his 1978 article on tuberculosis (TB) in twins, Comstock concluded that the 2.5-fold higher concordance rate for TB among monozygotic versus dizygotic twins in the Prophit survey of the 1950s implicated inherited susceptibility as a major risk factor for TB in humans. His analysis did not take into account strong imbalance of variables within subgroups, underestimating possible confounding effects of environmental factors.
To reconsider the role of environmental versus hereditary factors in determining the concordance rate of TB among twin pairs.
Reanalysis of the Prophit Survey.
A known Mycobacterium tuberculosis-positive or M. tuberculosis-negative sputum in the index TB case markedly influenced the odds ratio (OR) of concordance in the twin pairs. In 87 pairs with co-twins exposed to a sputum-negative index case, monozygotic and dizygotic twins did not differ in concordance for TB (OR, 1.1; 95% confidence interval [95% CI], 0.4-2.8). A higher concordance rate for TB among monozygotic versus dizygotic twins was confined to 106 pairs with the co-twins exposed to a sputum-positive index case (OR, 3.4; 95% CI, 1.6-7.2), and was highest in adolescent twins living together. ORs of TB concordance were proportional to intensity of exposure (sputum smear positivity, physical proximity between twin pairs, contagiousness of disease, and living together) rather than to zygosity.
In the Prophit survey of susceptibility to TB among twins, environmental factors (i.e., intensity of exposure to tubercle bacilli) outweigh the importance of hereditary factors. Environmental factors and the context of transmission should be given more emphasis when studying interindividual and population differences in susceptibility to infectious diseases such as TB.
在1978年关于双胞胎结核病（TB）的文章中，康斯托克得出结论，在20世纪50年代普罗菲特调查中，同卵双胞胎与异卵双胞胎之间结核病一致性率高出2.5倍，这表明遗传易感性是人类结核病的主要风险因素。他的分析没有考虑亚组内变量的强烈不平衡，低估了环境因素可能的混杂效应。
重新审视环境因素与遗传因素在决定双胞胎对结核病一致性率方面的作用。
对普罗菲特调查进行重新分析。
索引结核病病例中已知的结核分枝杆菌阳性或阴性痰液显著影响双胞胎对一致性的比值比（OR）。在87对双胞胎中，其同胞双胞胎接触痰液阴性索引病例，同卵双胞胎和异卵双胞胎在结核病一致性方面没有差异（OR，1.1；95%置信区间[95%CI]，0.4 - 2.8）。同卵双胞胎与异卵双胞胎之间结核病更高的一致性率仅限于106对同胞双胞胎接触痰液阳性索引病例（OR，3.4；95%CI，1.6 - 7.2），并且在共同生活的青少年双胞胎中最高。结核病一致性的OR与接触强度（痰液涂片阳性、双胞胎对之间的身体距离、疾病传染性和共同生活）成正比，而不是与合子性成正比。
在普罗菲特双胞胎结核病易感性调查中，环境因素（即接触结核杆菌的强度）比遗传因素更重要。在研究个体间和人群对结核病等传染病易感性差异时，应更加强调环境因素和传播背景。
