Risk ratio for initiation of conventional cigarette or e-cigarette use within the 6-month follow-up period

Study variable at baselineInitiation of conventional cigarette useInitiation of e-cigarette use
ARR#95% CIARR#95% CI
Substance use ever
 Binge drinking2.131.43–3.161.731.33–2.26
 Age >median1.380.92–2.050.870.67–1.13
 Migration background1.070.71–1.601.230.94–1.62
 School type “gymnasium”1.691.13–2.511.240.95–1.62
Personality and friend influence
 Sensation seeking >median1.751.17–2.601.391.06–1.83
 Friend waterpipe smoking0.960.59–1.541.551.07–2.23
 Friend conventional cigarette smoking1.561.03–2.371.100.83–1.45
 Friend e-cigarette vaping0.910.59–1.391.361.02–1.81

ARR: adjusted risk ratio; CI: confidence interval. #: statistically controlled for all variables in the table and participation in “Keep a Clear Head” programme, statistically relevant associations are marked in bold.