American Journal of Epidemiology © 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. Letter to the Editor RE: “DIETARY INTAKE OF ANTIOXIDANT VITAMINS AND CAROTENOIDS AND RISK OF DEVELOPING ACTIVE TUBERCULOSIS IN A PROSPECTIVE POPULATION-BASED COHORT” In a prospective cohort study, Soh et al. (1) examined the re- individuals who develop TB disease later in life may be in- lationships of consumption of speciﬁc antioxidant vitamins fected with extensively drug-resistant strands of TB (2). We and carotenoids with the risk of developing active tuberculosis encourage the authors to consider examining drug-resistant TB (TB). Future results among that study population could prove within this special cohort population or in future studies. We important in the research and investigation of latent TB disease. applaud Soh et al. for their work on this multifaceted public When attempting to examine relationships between expo- health issue (1) and encourage future research within this sures and outcomes, it is important to utilize methodology that cohort in order to better understand latent TB. actively screens for multiple confounding variables. In the United States, several factors are known to be afﬁliated with primary TB infection, including human immunodeﬁciency ACKNOWLEDGMENTS virus (HIV) infection, low socioeconomic status, and smoking (2). Conﬂict of interest: none declared. Soh et al. mentioned several limitations that should be con- sidered in future study designs, including the omission of die- tary and smoking changes from baseline, which may have REFERENCES signiﬁcantly biased the results. Additionally, the use of highest level of education as a proxy for socioeconomic status was 1. Soh AZ, Chee CBE, Wang YT, et al. Dietary intake of antioxidant vitamins and carotenoids and risk of developing suboptimal (1). Instead, questions pertaining to housing condi- active tuberculosis in a prospective population-based cohort tions and overcrowding should have been utilized because study. Am J Epidemiol. 2017;186(4):491–500. these conditions increase the likelihood of exposure to and 2. Centers for Disease Control and Prevention. Tuberculosis (TB). spread of TB from an epidemiologic perspective (3). Further- https://www.cdc.gov/tb/publications/factsheets/general/ more, the researchers did not examine HIV status but men- ltbiandactivetb.htm. Accessed September 25, 2017. tioned that Singapore has a relatively low rate of HIV. This aspect 3. Wanyeki I, Olson S, Brassard P, et al. Dwellings, crowding, and may be worth examining within that study population (1, 2). tuberculosis in Montreal. Soc Sci Med. 2006;63(2): 501–511. Their cohort study also presents opportunities for future research. The cohort consisted of older individuals who were Isabel Grifﬁn, Angel Algarin, Stephen White, hypothesized to be residents of Singapore during a time when and Gladys Ibanez (e-mail: igrif005@ﬁu.edu) TB incidence was as high as 300 per 100,000 persons in the Robert Stempel College of Public Health & Social Work, country. Today in Singapore, the current rate of TB is 40 per Florida International University, Miami, Florida 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, DOI: 10.1093/aje/kwx382 Downloaded from https://academic.oup.com/aje/advance-article-abstract/doi/10.1093/aje/kwx382/4804406 by Ed 'DeepDyve' Gillespie user on 08 June 2018
American Journal of Epidemiology – Oxford University Press
Published: Jan 12, 2018
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