Public Health Department, University of Otago, Wellington, Wellington, New Zealand.
Dean's Department, University of Otago, Wellington, Wellington, New Zealand.
BMJ Open. 2018 Oct 25;8(10):e020320. doi: 10.1136/bmjopen-2017-020320.
Adolescent smoking has declined in New Zealand and in many other countries since the late 1990s, yet the reasons for the decline are not well understood. We investigated the extent to which established risk factors for adolescent smoking (parental, sibling and peer smoking, and exposure to smoking in the home) explained the downward trend.
Trend analysis of repeat cross-sectional data from an annual nationally representative survey.
New Zealand.
Secondary school students aged 14-15 (n=398 221).
Regular (at least monthly) smoking.
For each risk factor (parental smoking, best friend smoking, older sibling smoking and past week exposure to smoking in the home) we plotted prevalence of exposure, 2002-2015. Next, using multivariable logistic regression, we modelled the trend in regular smoking (expressed as an OR for year) adjusting for age, sex, ethnicity and socioeconomic position. The risk factors were added to the model-individually and collectively-to test whether they attenuated the OR for year.
Exposure to all risk factors except 'past week exposure to smoking in the home' decreased between 2002 and 2015. We observed a strong downward trend in regular smoking among adolescents (OR=0.88 per year, 95% CI 0.88 to 0.88, p<0.001). 'Best friend smoking' was the only risk factor that significantly attenuated the trend. However, due to circularity, this factor provides an unsatisfactory explanation for population level smoking decline.
The established risk factors that we explored do not appear to have contributed to the remarkable decline in adolescent smoking in New Zealand between 2003 and 2015. Further research is needed to assess the possible contribution of factors outside our model, such as changes in the policy context, the social meaning of smoking and broader social and economic conditions.
自 20 世纪 90 年代末以来，新西兰和许多其他国家的青少年吸烟率都有所下降，但下降的原因尚不清楚。我们研究了已确定的青少年吸烟风险因素（父母、兄弟姐妹和同伴吸烟，以及在家中接触吸烟）在多大程度上解释了这一下降趋势。
对一项年度全国代表性调查的重复横断面数据进行趋势分析。
新西兰。
年龄在 14-15 岁的中学生（n=398221）。
定期（至少每月）吸烟。
对于每个风险因素（父母吸烟、最好的朋友吸烟、年龄较大的兄弟姐妹吸烟以及过去一周在家中接触吸烟），我们绘制了 2002-2015 年的暴露率。接下来，我们使用多变量逻辑回归，根据年龄、性别、种族和社会经济地位，调整了定期吸烟的趋势（表示为每年的比值比）。将风险因素逐个和集体添加到模型中，以检验它们是否减弱了每年的比值比。
除了“过去一周在家中接触吸烟”之外，所有风险因素的暴露率都在 2002 年至 2015 年间下降。我们观察到青少年定期吸烟的趋势呈明显下降趋势（每年下降 0.88，95%CI 0.88 至 0.88，p<0.001）。“最好的朋友吸烟”是唯一显著减弱这种趋势的风险因素。然而，由于循环性，该因素对人群吸烟率下降的解释并不令人满意。
我们探索的已确定风险因素似乎并没有促成 2003 年至 2015 年新西兰青少年吸烟率的显著下降。需要进一步研究，以评估我们模型之外的因素（如政策环境变化、吸烟的社会意义以及更广泛的社会和经济条件）可能做出的贡献。
