Impacts of smoke-free public places legislation on inequalities in youth smoking uptake: study protocol for a secondary analysis of UK survey data.

Smoke-free public places legislation has been introduced in many countries to protect the public from the harmful effects of secondhand smoking. While evaluations of smoke-free policies have demonstrated major public health benefits, the impact on youth smoking and inequalities in smoking remains unclear. This project aims to evaluate how smoke-free public places legislation in the UK has impacted on inequalities in youth smoking uptake, and how much of any impact is via changes in parental smoking behaviour. The study will constitute secondary analyses of UK data (from the British Household Panel Survey and the Understanding Society study). Merging these datasets gives coverage of the period from 1994 to 2016. Missing data will be handled using multiple imputation. The primary outcomes are the rates and inequalities in initiation, experimentation, escalation to daily smoking and quitting among youths aged 11–15 years. Secondary outcomes include the prevalence of smoking among parents of these youths. Discrete-time event history analysis will be conducted to examine whether changes in the probability of youth smoking transitions are associated with the implementation of the smoke-free public places legislation; and whether any observed effects differ by socioeconomic position and parental smoking. A multilevel logistic regression model will be used to investigate whether there is a step change or change in trend for the prevalence of parental smoking after the policy was implemented. The models will be adjusted for relevant factors (including cigarette taxation, the change in the legal age for purchase of cigarettes and e-cigarette prevalence) that may be associated with the implementation of the legislation. This project will use anonymised survey data which have been collected following independent ethical review. The dissemination of the study findings will adopt multiple communication channels targeting both scientific and non-scientific audiences.

许多国家都出台了公共场所禁烟立法，以保护公众免受二手烟的有害影响。虽然对禁烟政策的评估已显示出对公共健康的重大益处，但对青少年吸烟以及吸烟不平等现象的影响仍不明确。本项目旨在评估英国的公共场所禁烟立法如何影响青少年吸烟率的不平等，以及这种影响在多大程度上是通过父母吸烟行为的改变而产生的。 该研究将对英国的数据（来自英国家庭面板调查和理解社会研究）进行二次分析。合并这些数据集可涵盖1994年至2016年期间。缺失数据将采用多重填补法处理。主要结果是11 - 15岁青少年开始吸烟、尝试吸烟、发展为每日吸烟以及戒烟的比率和不平等情况。次要结果包括这些青少年的父母吸烟率。将进行离散时间事件史分析，以检验青少年吸烟转变的概率变化是否与公共场所禁烟立法的实施有关；以及观察到的任何影响是否因社会经济地位和父母吸烟情况而异。将使用多层逻辑回归模型来调查政策实施后父母吸烟率是否有阶跃变化或趋势变化。模型将根据可能与立法实施相关的相关因素（包括香烟税收、购买香烟的法定年龄变化以及电子烟流行率）进行调整。 本项目将使用经过独立伦理审查后收集的匿名调查数据。研究结果的传播将采用多种传播渠道，面向科学和非科学受众。