In a prospective cohort study, Soh et al. (1) examined the relationships of consumption of specific antioxidant vitamins and carotenoids with the risk of developing active tuberculosis (TB). Future results among that study population could prove important in the research and investigation of latent TB disease. When attempting to examine relationships between exposures and outcomes, it is important to utilize methodology that actively screens for multiple confounding variables. In the United States, several factors are known to be affiliated with primary TB infection, including human immunodeficiency virus (HIV) infection, low socioeconomic status, and smoking (2). Soh et al. mentioned several limitations that should be considered in future study designs, including the omission of dietary and smoking changes from baseline, which may have significantly biased the results. Additionally, the use of highest level of education as a proxy for socioeconomic status was suboptimal (1). Instead, questions pertaining to housing conditions and overcrowding should have been utilized because these conditions increase the likelihood of exposure to and spread of TB from an epidemiologic perspective (3). Furthermore, the researchers did not examine HIV status but mentioned that Singapore has a relatively low rate of HIV. This aspect may be worth examining within that study population (1, 2). Their cohort study also presents opportunities for future research. The cohort consisted of older individuals who were hypothesized to be residents of Singapore during a time when TB incidence was as high as 300 per 100,000 persons in the country. Today in Singapore, the current rate of TB is 40 per 100,000 persons (1). Soh et al. believed that most of the TB cases in the cohort were likely cases of disease reactivation (2). According the Centers for Disease Control and Prevention, individuals who develop TB disease later in life may be infected with extensively drug-resistant strands of TB (2). We encourage the authors to consider examining drug-resistant TB within this special cohort population or in future studies. We applaud Soh et al. for their work on this multifaceted public health issue (1) and encourage future research within this cohort in order to better understand latent TB. Acknowledgments Conflict of interest: none declared. References 1 Soh AZ , Chee CBE , Wang YT , et al. . Dietary intake of antioxidant vitamins and carotenoids and risk of developing active tuberculosis in a prospective population-based cohort study . Am J Epidemiol . 2017 ; 186 ( 4 ): 491 – 500 . Google Scholar CrossRef Search ADS PubMed 2 Centers for Disease Control and Prevention . Tuberculosis (TB). https://www.cdc.gov/tb/publications/factsheets/general/ltbiandactivetb.htm. Accessed September 25, 2017. 3 Wanyeki I , Olson S , Brassard P , et al. . Dwellings, crowding, and tuberculosis in Montreal . Soc Sci Med . 2006 ; 63 ( 2 ): 501 – 511 . Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: firstname.lastname@example.org. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)
American Journal of Epidemiology – Oxford University Press
Published: Jan 12, 2018
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