A comparison of prevalence estimates of smoking, alternative nicotine and alcohol use in Great Britain collected via telephone versus face-to-face: Smoking and Alcohol Toolkit surveys

Background and Aims: Due to the COVID-19 pandemic, the survey mode of the Smoking and Alcohol Toolkit Study, a long-running repeat cross-sectional survey, had to change from face-to-face to telephone interviews. This study aimed to assess similarities and differences in sociodemographic, smoking, alternative nicotine and alcohol use estimates between the two survey modes, to understand the potential impacts of this change in methodology on prevalence estimates and trends over time. Design: After COVID-19 restrictions were lifted, we conducted parallel telephone and face-to-face household surveys in March 2022 and in January to March 2024, using a hybrid of random and quota sampling. Data from both years were aggregated. Setting and Participants: People aged 16+ years living in private households in Great Britain. Measurements: Sociodemographic characteristics, nicotine and alcohol use related estimates and their 95% CIs - unweighted and weighted - collected via telephone versus face-to-face in a household. Findings: In the unweighted analyses, the telephone sample included slightly younger and less socioeconomically advantaged groups than the face-to-face sample. After the samples were weighted, estimates of sociodemographic characteristics and nicotine and alcohol use were generally consistent across methodologies, including daily cigarette smoking (face-to-face: 11.1% [10.1-12.1] vs. telephone: 10.6% [9.5-11.7]), non-daily cigarette smoking (face-to-face: 2.7% [2.2-3.3] vs. telephone: 3.4% [2.8-4.1]), and e-cigarette use among people who smoke (face-to-face: 27.0% [23.5-30.5] vs. telephone: 29.3% [25.4-33.3]). However, compared with telephone participants, a lower proportion of face-to-face participants reported currently using e-cigarettes (face-to-face: 6.4% [5.6-7.1] vs. telephone: 10.4% [9.3-11.5]), and a higher proportion reported never drinking alcohol (face-to-face: 31.1% [29.7-32.5] vs. telephone: 25.0% [23.5-26.5]) and never having 6 or more standard drinks on one occasion (face-to-face: 46.6% [44.7-48.5] vs. telephone: 40.2% [38.4-42.1]). More participants provided "don't know" or "refused" responses in the telephone compared with the face-to-face interview, including in response to questions about tobacco use, e-cigarette device type, and the number of standard drinks on a typical day. Conclusions: Face-to-face and telephone surveys generally yield similar estimates of nicotine and alcohol use. However, there may be some underreporting of vaping and drinking in a face-to-face survey conducted in the home compared with telephone.