Yasmina Molero,1–3 Johan Zetterqvist,1 Paul Lichtenstein,1 Catarina Almqvist,1,4 Jonas F Ludvigsson1,5–7



1Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden; 2Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, & Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden; 3Department of Psychiatry, Warneford Hospital, University of Oxford, Oxford, UK; 4Paediatric Allergy and Pulmonology Unit at Astrid Lindgren Children’s Hospital, Karolinska University Hospital of Paediatrics, Stockholm, Sweden; 5Department of Paediatrics, Örebro University Hospital, Örebro, Sweden; 6Division of Epidemiology and Public Health, School of Medicine, University of Nottingham, Nottingham, UK; 7Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY, USA



Background: Prior evidence shows that environmental tobacco smoke is a risk factor for respiratory tract infections, wheeze, and asthma. Nicotine replacement therapy has been shown to increase smoking cessation. However, no prior studies have explored if parental use decreases the risk of bronchitis/bronchiolitis and asthma in the offspring.

Objective: To examine whether nicotine replacement therapy varenicline, given to parents, was associated with a reduction in bronchitis/bronchiolitis and/or asthma in their children.

Methods: This study is a population-based cohort study, linking data from nationwide registers, and using a within-individual design that minimizes selection effects and controls for time-invariant confounding factors. Participants included 37,420 parents with a collected prescription of varenicline with 72,392 offspring <18 years of age. Exposure was defined as collected prescriptions of varenicline among the parents. Primary outcomes were offspring hospital visits for bronchitis/bronchiolitis (ICD10: J20 or J21) and offspring hospital visits for asthma (ICD10: J45).

Results: Parental varenicline treatment was associated with a lower rate of visits for bronchitis/bronchiolitis in their children (incidence rate ratio [IRR]=0.67; 95% CI=0.50–0.91), but no association was found for asthma (IRR=1.08; 95% CI=0.97–1.19). The rate reduction of bronchitis/bronchiolitis was similar when we restricted data to children aged 0–3 years (IRR=0.71; 95% CI=0.52–0.97) and to maternal varenicline treatment (IRR=0.64; 95% CI=0.43–0.96). When restricting the outcomes to unplanned visits only (ie, excluding booked appointments, follow-ups, and referrals), no associations were found (IRR=0.72, 95% CI=0.51–1.02).

Conclusion: In this cohort study, nicotine replacement treatment in parents was associated with reduced hospital visits for bronchitis/bronchiolitis in their children.



Keywords: asthma, wheezing, nicotine replacement therapy, varenicline, environmental tobacco smoke, child environmental tobacco smoke exposure

