Dose–response relationship between BMI and tuberculosis

Tuberculosis remains a pressing public health problem in China, especially in regions with limited resources and high disease burden. Recognizing that factors such as age, sex, diabetes, and undernutrition may influence TB risk, this study set out to clarify the role of body mass index (BMI) in determining TB incidence in adults. The researchers conducted a large-scale, prospective cohort study in Dongchuan County, Yunnan Province, following over 26,000 participants for more than two years.

The methodology was robust, using repeated TB screenings and carefully measured BMI classifications. By categorizing individuals into underweight, normal weight, and overweight/obese groups, the investigators were able to track how different BMI levels related to new cases of active TB. They found that TB incidence rates were highest among those who were underweight and lowest among individuals classified as overweight or obese. Importantly, the study documented a clear dose–response relationship: for every one-unit increase in BMI, TB incidence decreased by almost 8%.

Multivariate analyses confirmed that overweight and obesity were significantly protective against TB even after adjusting for important confounders, including diabetes status and prior TB history. Subgroup analyses revealed that this protective effect was consistent in men, women, and the elderly, suggesting the findings are broadly applicable across different demographic profiles.

These results align well with prior evidence linking malnutrition to higher susceptibility to TB infection and progression. Notably, the study highlighted that BMI improvements could have contributed to recent TB declines in China, underscoring the role of nutritional status in TB control strategies. While underweight status was associated with higher TB rates, this association did not reach statistical significance in adjusted models, possibly due to limited power in the underweight subgroup.

Overall, this research provides valuable evidence that higher BMI can be an independent protective factor against TB. These findings support prioritizing targeted TB screening among individuals with low BMI and suggest that community-level nutritional interventions could help lower TB incidence further. For policymakers and clinicians, the study highlights an opportunity to integrate nutrition-focused strategies into TB prevention programs, especially in regions where undernutrition remains prevalent.

References:

1. Chen, J., Zha, S., Hou, J., Lu, K., Qiu, Y., Yang, R., Li, L., Yang, Y. and Xu, L., 2022. Dose–response relationship between body mass index and tuberculosis in China: a population-based cohort study. BMJ open, 12(3), p.e050928.