Airway reactivity to mannitol is similarly increased in chronic cigarette and water pipe smokers

Background In contrast to cigarette smoking, the association between water pipe smoking and airway hyperresponsiveness remains widely unexplored. Methods A bronchoprovocation challenge with mannitol was performed in young adults recruited at the University of Basel, Switzerland. Subjects were categorized as acute water pipe smokers (single episode of water pipe smoking, no or <0.5 pack-years cigarette smoking); chronic water pipe smokers (weekly for ≥4 weeks, no or <0.5 pack-years cigarette smoking); cigarette smokers (no water pipe smokers); and never-smokers (no cigarette or water pipe smokers). Primary outcomes were airway reactivity as measured by the response-to-dose ratio (RDR) and airway responsiveness measured by the provocation dose to cause a 15% fall in forced expiratory volume in 1s (FEV1; PD15). Results Seventy-four subjects with a mean age of 22.5±2.5 years and FEV1 % predicted 90.1%±8.6% were included. Subgroups were matched in terms of age, gender, and spirometry results. RDR in chronic water pipe smokers and cigarette smokers was similar (0.013%/mg [0.010-0.015] vs 0.023%/mg [0.011-0.051], respectively; p=0.12) but significantly higher than in never-smokers (0.007%/mg [0.005-0.010], p<0.01). Neither a history of asthma (p=0.88) nor a positive skin prick test (p=0.69) was associated with increased airway reactivity to the mannitol challenge test. PD15 differed significantly between cigarette smokers and never-smokers (155 mg [115-395] vs 315 mg [155-475], respectively; p=0.04). Conclusion Weekly water pipe smoking may increase airway reactivity to a similar extent as cigarette smoking.