Respiratory function, functional capacity, dyspnea, and sleep quality in young adults using the IQOS heated tobacco...

This matched cross-sectional study compared respiratory function, respiratory muscle strength, functional exercise capacity, dyspnea, and sleep quality between young IQOS users and matched control subjects. This study involved 31 young adult IQOS users and 31 age/sex/body mass index-matched never-tobacco users who underwent a standardized testing protocol during a single visit. Spirometry, maximal inspiratory pressure (MIP), 6-min walk test (6MWT), modified Medical Research Council (mMRC) dyspnea scale, modified Borg Scale (mBorg), and Pittsburgh Sleep Quality Index (PSQI) scores were compared. While mean resting lung functions were similar between groups (all p > 0.05), IQOS users had shorter 6MWT distances (591.1 [580.2 - 638.4] meters vs. 626.0 [600.5 - 683.8] meters, p = 0.003, r = 0.53) and higher mMRC dyspnea scores (median mMRC Grade = 1 (0-1) in IQOS users vs 0 (0-0) in controls, p < 0.001, r = 0.62), higher mBorg dyspnea scores at the end of the 6MWT (median end-6MWT mBorg rating scale 1 [0-2] vs 0 [0-1], p = 0.001, r = 0.57), and poor sleep quality (PSQI global score 6.32 ± 2.63 vs 4.58 ± 1.61, p = 0.012, r = 0.45). Additionally, while MIP values tended toward being lower in IQOS users, these differences were statistically nonsignificant (p = 0.090). In conclusion, young exclusive IQOS users showed lower functional exercise capacity, greater dyspnea, and poorer sleep quality than matched never-users despite comparable resting spirometry, and these hypothesis-generating findings warrant longitudinal evaluation with biochemical exposure verification.