評估結核病接觸者在不同接觸情境的潛在感染風險

Assessing the infection risk of Tuberculosis (TB) contacts in different case-contact contexts

目標：本研究旨在探討台灣結核病發病者與接觸者之間不同的接觸情境與社會經濟條件，對於結核病感染風險的影響。方法：研究材料是疾管署在2010-2012年的台灣結核病接觸者調查資料，本研究建立接觸者與指標個案之接觸網絡，以迴歸模式分析接觸者感染風險因子，以及結核病潛伏感染接觸效率較高的社會情境。結果：在3,297名接觸者中，控制痰塗片陽性與接觸者年齡因素下，指標個案為原住民族群、居住於低度都市化地區、指標個案學歷大學以下、低網絡連結數是接觸者感染風險的獨立預測因子。在831名感染的接觸者中，導致結核病感染的接觸效率較高的社會關係，主要是孩童與青少年的親戚關係、在低度都市化的社區近鄰關係，以及醫療照護的接觸關係。結論：本研究發現在缺乏接觸者個人社經資料的情況下，指標個案的社會經濟條件即可做為接觸者感染風險的預測因子；另一方面，利用接觸效率的概念，可證實致病風險在不同社會關係、城鄉與不同年齡層的社會情境下有別，區辨這些特性有助於防疫調查找出具有高度感染風險的接觸者。

Objectives: The risk of tuberculosis (TB) infection within different case-contact contexts is unknown. This study aimed to assess the role of different social contacts in the risk of latent TB infection (LTBI). Methods: We analyzed the records of the TB contact investigation conducted by the Taiwan Centers for Disease Control (CDC) between 2010 and 2012, including 3297 contacts. Among the 3297 contacts, 831 were infected. We propose two TB risk indices: the probability of getting infected; and contact efficiency for investigating the risk factors in terms of different social contacts and demographics using multivariate regression analysis. Results: After adjusting the smear-positivity and age of contacts, we identified statistically significant social-demographic characteristics of an index case who had a higher probability of spreading TB to contacts. These social-demographic characteristics included aboriginal race, residence in non-urban areas, low-level education, and low degree of contact. Among 831 infected contacts, we also identified the types of social contacts with high-contact efficiency for TB infection, including the relationships of relatives among young people 0-14 years of age, the relationship with neighbors > 55 years of age in the non-urban areas, and interactions with home care providers. Conclusions: By analyzing case-contact contexts, we conclude that social-demographic characteristics of an index case can be used to assess the probability of TB spread. Furthermore, contact efficiency differs from case-contact contexts and implies that profiling significant types of social contacts could be beneficial to identify high-risk contacts in a TB contact investigation.