Early-life lower respiratory tract infection (LRTI) and risk of school-age asthma - A population-based cohort study

<bold>Background:</bold> LRTI is a known risk factor for asthma. However, there is a lack of population-based data with diagnosis verified in specialist care. <bold>Aim:</bold> To study the association between diagnosed LRTI <2 years and asthma 6-14 years in a population sample from Mid-Norway. <bold>Methods:</bold> Registry linkage of the Medical Birth Registry (2008–2018) with the Norwegian Patient Registry. Generalized estimating equations logistic regression models (adjusted for sex, maternal asthma, preterm birth, atopy, birth year) were applied to estimate asthma risk per year from age 6 to 14, by early-life exposure to LRTI. <bold>Results/conclusion:</bold> 37566 children were included, of whom 4.2% developed asthma (Table). If LRTI <2 years asthma diagnosis at 6-14 years was more likely (fully adjusted odds ratio 3.25, 95% confidence interval: 2.86–3.70). Asthma prevalence increased with the number of LRTIs (Figure 1) but not with age at first LRTI (Figure 2). <table-wrap><object-id>erj;64/suppl_68/PA3131/TB1</object-id><object-id>T1</object-id><object-id>TB1</object-id><table><colgroup><col></col><col></col><col></col></colgroup><tbody><tr><td></td><td>Asthma n= 1588</td><td>No asthma n=35 978</td></tr><tr><td>Girls</td><td>627 (39%)</td><td>17 608 (49%)</td></tr><tr><td>LRTI <2 years</td><td>378 (24%)</td><td>2 410 (6.7%)</td></tr><tr><td>Maternal asthma</td><td>146 (9.2%)</td><td>1 237 (3.4%)</td></tr><tr><td>Atopy <2 years</td><td>837 (53%)</td><td>9 327 (26%)</td></tr><tr><td>Preterm birth</td><td>190 (12%)</td><td>2 708 (7.5%)</td></tr></tbody></table></table-wrap> <fig><object-id>erj;64/suppl_68/PA3131/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <fig><object-id>erj;64/suppl_68/PA3131/F2</object-id><object-id>F2</object-id><object-id>F2</object-id><graphic></graphic></fig>