Behavioral Risk Factor Surveillance System

Data were collected as part of the 2014 Minnesota Adult Tobacco Survey, which uses a random digit dialing (RDD) methodology to obtain a cross-sectional sample of Minnesotan adults aged 18 years or older. Two sampling frames were used, one that included landline numbers and another that included cell phone numbers. Prescreening calls identified households and selected individuals within households; the main survey instrument was subsequently administered. A rigorous calling protocol was used, and letters were mailed to refusers and non-responders when addresses were available. Attempts were made to convert refusers. RDD response rates calculated by American Association for Public Opinion Research methodology were 25.2% for the landline sampling frame and 18.2% for the cell phone frame.²³ Sampling weights were calculated based on sampling frame response rates and demographic characteristics known to be correlated with tobacco use behaviours, to obtain unbiased population level estimates. More methodological detail is available at http://www.mnadulttobaccosurvey.org. The final sample in 2014 included 9304 participants; 9301 of the participants provided valid responses for the items considered in this analysis.
Smoking status was established according to the historically common Behavioural Risk Factor Surveillance System (BRFSS) methodology. Current smokers had smoked ≥100 cigarettes in their lifetime and now smoked ‘every day’ or ‘some days’; former smokers had smoked ≥100 cigarettes in their lifetime, but now smoked ‘not at all’; and never smokers had not smoked ≥100 cigarettes in their lifetime. E-cigarette use was measured by two items. Participants were first asked, “Have you ever used an electronic cigarette, even just one time in your entire life?” Affirmative answers were followed by the question, “During the past 30 days, on how many days did you use e-cigarettes?” Responses were entered as integers by the data collector; respondents offering non-integer responses were prompted to provide an integer. Respondents who had ever used e-cigarettes were asked whether each of the following was a reason for use: to quit other tobacco products; to cut down on other tobacco products because they are affordable; because they are available in menthol flavour; because they are available in flavours other than menthol; to use them in places where other tobacco products are not allowed; curiosity about e-cigarettes; and because you believe these might be less harmful than other tobacco products. Based on the findings of Pepper et al^{16 (link)}, reasons were classified as goal oriented or non-goal oriented.
All analyses were conducted with the R software package, V.3.1.1, using the survey package V.3.30-3. All population estimates are presented with 95% CIs. Where direct comparisons of CIs are insufficient to establish significance at the α=0.05 level (ie, where CIs overlapped), we report p values for pairwise comparisons that were calculated using linear regression.