Association of accumulated number of underweight with occurrence of tuberculosis

Abstract Underweight might be a risk factor of tuberculosis (TB), but the association between duration of underweight and occurrence of TB is inconclusive. The objective of this study was to determine whether there is a difference in occurrence of TB according to the cumulative number of underweight in an intermediate TB burden country. The National Health Insurance database was used. Eligible subjects were individuals without history of TB before 2006, and who underwent national health examination between January 2009 and 31 December 2010. Included individuals in the analysis were followed until 31 December 2017. Accumulated number of underweight was defined as the number of times recorded as underweight during the national health examination over four consecutive years. The primary outcome of the study was newly diagnosed TB according to accumulated number of underweight. Among a study population of 2,396,434, TB was identified in 9,322 (3.89%) cases. A high accumulated number of underweight and low body mass index (BMI) level were significantly associated with occurrence of TB. This association remained consistent after adjusting for demographic factors and underlying diseases. In stratified analysis based on age, sex, diabetes (DM), hypertension (HTN), and waist circumference (WC) in metabolic syndrome (MS), the accumulated number of underweight was related consistently to occurrence of TB. A high accumulated number of underweight was associated with increased risk of TB.