Association of duration of undernutrition with occurrence of tuberculosis.

Undernutrition is a risk factor of tuberculosis (TB), but the association between duration of undernutrition 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 duration of undernutrition expressed as accumulated number of underweight in Republic of Korea, an intermediate TB burden country. The National Health Insurance database was used.Eligible subjects were individuals who received a national health examination between 1 and 2009 and 31 December 2010, and who also had received health examinations for four consecutive years prior to 2009.Finally 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 over four consecutive years. The 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. The highest accumulated number of underweight was significantly associated with occurrence of TB (adjusted hazard ratio [aHR] 2.563, 95% CI 2.319-2.833). This association remained consistent after adjusting for demographic factors and underlying diseases (aHR 3.326, 95% CI 3.004-3.84). In stratified analysis based on age, sex, diabetes (DM), hypertension (HTN), and waist circumference (WC) in metabolic syndrome (MS), age and sex were identified as effect modifiers. Occurrence of TB was significantly higher in the group with the highest accumulated number of underweight under 65 years of age.