Megan Murray, Harvard University
Nutritional Risk Factors for TB Progression: Results of a Longitudinal Cohort Study
We followed a cohort of household contacts of microbiologically confirmed index TB patients over a one year period for TB infection and progression to disease. Among 6751 HIV-negative household contacts with viable baseline blood samples, 180 developed secondary TB during follow-up. We used risk set sampling to identify 709 matched controls from those who did not develop TB disease. After controlling for possible confounders, we found that vitamin A deficiency was associated with a 10-fold increase in risk of TB disease among household contacts (aOR 10.42; 95% CI 4.01–27.05; p < 0.001). This association was dose-dependent with stepwise increases in TB disease risk with each decreasing quartile of vitamin A level. These data are consistent findings from recent studies among HIV infected individuals at risk for TB and with data that suggest that some measures of T-cell mediated immunity are improved by increasing Vitamin A to levels higher than those required to maintain normal vision.