Analysis of two retrospective cohorts in Taiwan revealed that body mass index (BMI) at baseline was predictive of incident active tuberculosis. This research elucidated the role of diabetes played in the relationship between BMI and tuberculosis published in Clinical Infectious Diseases in March. The study was conducted by a research team led by Dr. Hsien-Ho Lin from the National Taiwan University College of Public Health.
Two population-based cohorts of nearly 170,000 individuals with more than seven years of follow-up time were included in the analysis: one consisted of adult participants from three waves of National Health Interview Surveys conducted in 2001, 2005 and 2009, and the other was those recruited from a community- based voluntary health screening service in New Taipei City from 2005 to 2008. It was found that the obese population in the respective cohort had 67.2 percent and 63.5 percent reductions in tuberculosis hazard whereas the underweight individuals had 2.28 and 2.44 fold increase in tuberculosis risk compared to normal-weight population.
The mediation analysis in this research quantified the direct association between BMI and tuberculosis and the indirect one mediated through diabetes. The analysis showed that the direct pathway dominated the overall association. They also reported that overweight individuals with diabetes were at equivalent or lower risks of tuberculosis compared with normal-weight individuals without diabetes.
The results from this study have significant implications for the global syndemics of obesity, diabetes, and tuberculosis. With the global nutrition transition, countries are expected to have rising prevalence of obesity and diabetes in the future. The potential impact of nutrition transition on global tuberculosis epidemiology has to be carefully evaluated. Moreover, the interplay between host metabolism and immunology associated with tuberculosis provides a new insight into potential strategies to tuberculosis elimination.