Department of Population Health, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND.
Behavioral Sciences Group, Sanford Research, Sioux Falls, SD.
Nicotine Tob Res. 2020 Jun 12;22(7):1123-1130. doi: 10.1093/ntr/ntz157.
The growing popularity of electronic cigarettes (e-cigarettes) among youth raises concerns about possible causal effects on conventional cigarette smoking. However, past research remains inconclusive due to heavy confounding between cigarette and e-cigarette use. This study uses propensity score methods to robustly adjust for shared risk in estimating the relationship between e-cigarette use and conventional smoking.
Cross-sectional data from 8th and 10th graders were drawn from the 2015-2016 waves of Monitoring the Future (n = 12 421). The effects of (1) lifetime and (2) current e-cigarette use on (A) lifetime and (B) current conventional cigarette smoking were examined using logistic regression analyses with inverse propensity weighting based on 14 associated risk factors.
After accounting for the propensity for using e-cigarettes based on 14 risk factors, both lifetime and current e-cigarette use significantly increased the risk of ever smoking a conventional cigarette (OR = 2.49, 95% CI = 1.77 to 3.51; OR = 2.32, 95% CI = 1.66 to 3.25, respectively). However, lifetime (OR = 2.17, 95% CI = 0.62 to 7.63) and current e-cigarette use (OR = 0.95, 95% CI = 0.55 to 1.63) did not significantly increase the risk of current conventional cigarette smoking.
E-cigarette use does not appear to be associated with current, continued smoking. Instead, the apparent relationship between e-cigarette use and current conventional smoking is fully explained by shared risk factors, thus failing to support claims that e-cigarettes have a causal effect on concurrent conventional smoking among youth. E-cigarette use has a remaining association with lifetime cigarette smoking after propensity score adjustment; however, future research is needed to determine whether this is a causal relationship or merely reflects unmeasured confounding.
This study examines the relationship between e-cigarette use and conventional smoking using inverse propensity score weighting, an innovative statistical method that produces less-biased results in the presence of heavy confounding. Our findings show that the apparent relationship between e-cigarette use and current cigarette smoking is entirely attributable to shared risk factors for tobacco use. However, e-cigarette use is associated with lifetime cigarette smoking, though further research is needed to determine whether this is a causal relationship or merely reflects unaccounted-for confounding. Propensity score weighting produced significantly weaker effect estimations compared to conventional regression control.
电子烟在青少年中的普及引起了人们对其可能对传统香烟吸烟产生因果影响的关注。然而，由于香烟和电子烟使用之间存在严重的混杂因素，过去的研究结果仍不确定。本研究使用倾向评分方法，通过对 14 个相关风险因素进行分析，对电子烟使用与常规吸烟之间的关系进行稳健调整，以消除混杂因素。
从 2015-2016 年监测未来（Monitoring the Future）的 8 年级和 10 年级学生中抽取横断面数据（n=12421）。使用基于 14 个相关风险因素的逆概率加权的逻辑回归分析，分别检验（1）终生和（2）当前电子烟使用对（A）终生和（B）当前传统香烟吸烟的影响。
在基于 14 个风险因素的电子烟使用倾向得分基础上进行调整后，终生和当前电子烟使用均显著增加了吸传统香烟的风险（OR=2.49，95%CI=1.77 至 3.51；OR=2.32，95%CI=1.66 至 3.25）。然而，终生（OR=2.17，95%CI=0.62 至 7.63）和当前电子烟使用（OR=0.95，95%CI=0.55 至 1.63）并不显著增加当前传统香烟吸烟的风险。
电子烟的使用似乎与当前持续吸烟无关。相反，电子烟使用与当前传统香烟使用之间的明显关系完全可以用共同的风险因素来解释，因此，不能支持电子烟对青少年同时使用传统香烟有因果影响的说法。在倾向评分调整后，电子烟的使用与终生吸烟仍存在关联；然而，需要进一步研究来确定这是否是一种因果关系，还是仅仅反映了未测量的混杂因素。
本研究使用逆概率得分加权法（一种创新的统计方法）来检验电子烟使用与传统吸烟之间的关系，这种方法在存在严重混杂因素的情况下，可以产生偏差较小的结果。我们的研究结果表明，电子烟使用与当前吸烟之间的明显关系完全是由吸烟的共同风险因素造成的。然而，电子烟的使用与终生吸烟有关，尽管需要进一步的研究来确定这是否是一种因果关系，还是仅仅反映了未考虑到的混杂因素。与传统回归控制相比，倾向评分加权法产生的效应估计值要弱得多。
