Body mass index and incidence of tuberculosis.

The association between body mass index (BMI) and incidence of tuberculosis was studied among 1,717,655 persons older than 14 years who were followed for 8-19 years. The incidence of pulmonary tuberculosis decreased with increasing BMI. The trend was roughly linear on the log scale, and was the same for both sexes and all age groups. X-ray-positive (calcification, pleural changes, infiltration) individuals showed the same trend, but on a much higher level than X-ray-negative individuals. When the total observation period was subdivided according to duration, the trend was found to be only slightly less steep for 10-19 years than for 0-4 and 5-9 years. When the material was divided simultaneously by group of observation years and by miniature X-ray findings, the association persisted. No association was seen between the incidence of other forms of tuberculosis and BMI. For persons reported with tuberculosis, a slightly decreasing mortality of tuberculosis was seen with increasing BMI, while mortality, all causes, seemed to have a slightly U-shaped association with BMI.