When we further stratified non-pneumonia control episodes based on the presence or absence of extra-pulmonary infection (n = 36 vs. n = 75), non-pneumonia control episodes with concurrent extra-pulmonary infection had a median NAT score of 2 on the day of BAL collection, while those without extra-pulmonary infection had a median score of 1 (P = 0.014, Mann–Whitney U test). Here, BRD2 is linked to pneumonia.