Previous tuberculosis infection associated with increased frequency of asthma and respiratory symptoms in a Nordic–Baltic multicentre population study

Abstract

Background Tuberculosis (TB) infection induces profound local and systemic, immunological and inflammatory changes that could influence the development of other respiratory diseases; however, the association between TB and asthma is only partly understood. Our objective was to study the association of TB with asthma and respiratory symptoms in a Nordic–Baltic population-based study. Methods We included data from the Respiratory Health in Northern Europe (RHINE) study, in which information on general characteristics, TB infection, asthma and asthma-like symptoms were collected using standardised postal questionnaires. Asthma was defined based on asthma medication usage and/or asthma attacks 12 months prior to the study, and/or by a report of ≥three out of five respiratory symptoms in the last 12 months. Allergic/nonallergic asthma were defined as asthma with/without nasal allergy. The associations of TB with asthma outcomes were analysed using logistic regressions with adjustments for age, sex, smoking, body mass index and parental education. Results We included 8379 study participants aged 50–75 years, 61 of whom reported having had TB. In adjusted analyses, participants with a history of TB had higher odds of asthma (OR 1.99, 95% CI 1.13–3.47). The associations were consistent for nonallergic asthma (OR 2.17, 95% CI 1.16–4.07), but not for allergic asthma (OR 1.20, 95% CI 0.53–2.71). Conclusion We found that in a large Northern European population-based cohort, persons with a history of TB infection more frequently had asthma and asthma symptoms. We speculate that this may reflect long-term effects of TB, including direct damage to the airways and lungs, as well as inflammatory responses.