Smoke-free legislation and paediatric hospitalisations for acute respiratory tract infections: national quasi-experimental study with unexpected findings and important methodological implications

Been, J. V., Mackay, D. F. , Millett, C., Soyiri, I., van Schayck, C. P., Pell, J. P. and Sheikh, A. (2018) Smoke-free legislation and paediatric hospitalisations for acute respiratory tract infections: national quasi-experimental study with unexpected findings and important methodological implications. Tobacco Control, 27(e2), e160-e166. (doi: 10.1136/tobaccocontrol-2017-053801) (PMID:29079584)

Abstract

We investigated whether Scottish implementation of smoke-free legislation was associated with a reduction in unplanned hospitalisations or deaths ('events') due to respiratory tract infections (RTIs) among children. Interrupted time series (ITS). Children aged 0-12 years living in Scotland during 1996-2012. National comprehensive smoke-free legislation (March 2006). Acute RTI events in the Scottish Morbidity Record-01 and/or National Records of Scotland Death Records. 135 134 RTI events were observed over 155 million patient-months. In our prespecified negative binomial regression model accounting for underlying temporal trends, seasonality, sex, age group, region, urbanisation level, socioeconomic status and seven-valent pneumococcal vaccination status, smoke-free legislation was associated with an immediate rise in RTI events (incidence rate ratio (IRR)=1.24, 95% CI 1.20 to 1.28) and an additional gradual increase (IRR=1.05/year, 95% CI 1.05 to 1.06). Given this unanticipated finding, we conducted a number of post hoc exploratory analyses. Among these, automatic break point detection indicated that the rise in RTI events actually preceded the smoke-free law by 16 months. When accounting for this break point, smoke-free legislation was associated with a gradual decrease in acute RTI events: IRR=0.91/year, 95% CI 0.87 to 0.96. Our prespecified ITS approach suggested that implementation of smoke-free legislation in Scotland was associated with an increase in paediatric RTI events. We were concerned that this result, which contradicted published evidence, was spurious. The association was indeed reversed when accounting for an unanticipated antecedent break point in the temporal trend, suggesting that the legislation may in fact be protective. ITS analyses should be subjected to comprehensive robustness checks to assess consistency. [Abstract copyright: © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.]

• Item Type: Articles
• Additional Information: This work was funded by a Thrasher Research Fund Early Career Award (NR-0166) and the International Pediatric Research Foundation Young Investigators Exchange Programme. JVB is furthermore supported by fellowship grants from the Erasmus University Medical Centre and the Netherlands Lung Foundation (4.2.14.063JO).
• Keywords: Prevention, priority/special populations, public policy, secondhand smoke
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Mackay, Professor Daniel and Pell, Professor Jill
• Authors: Been, J. V., Mackay, D. F., Millett, C., Soyiri, I., van Schayck, C. P., Pell, J. P., and Sheikh, A.
• College/School: College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health
• Journal Name: Tobacco Control
• Publisher: BMJ Publishing Group
• ISSN: 0964-4563
• ISSN (Online): 1468-3318
• Published Online: 27 October 2017
• Copyright Holders: Copyright © 2017 The Authors
• First Published: First published in Tobacco Control 27(e2): e160e166
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher