Table 2.

Crude and adjusted association between exclusive cigarette smokers, exclusive e-cigarette users, never users and respiratory wheezing

Model	Covariates included	Exclusive e-cigarette users	Never users	Exclusive cigarette smokers
Model 1	Crude	Reference	0.61 (0.48–0.77), p < 0.001	2.25 (1.76–2.88), p < 0.001
Model 2	+ Age group, Sex	Reference	0.60 (0.47–0.76), p < 0.001	2.29 (1.79–2.93), p < 0.001
Model 3	+ Deprivation	Reference	0.65 (0.51–0.83), p < 0.001	2.24 (1.75–2.88), p < 0.001
Model 4	+ Longstanding illness, COPD, Asthma	Reference	0.60 (0.46–0.80), p < 0.001	1.98 (1.48–2.63), p < 0.001
Model 5	+ General health, Alcohol, Age of smoking initiation	Reference	0.67 (0.32–1.42), p = 0.298	1.90 (1.41–2.56), p < 0.001
Final model	+ Second-hand smoke exposure	Reference	0.66 (0.31–1.40), p = 0.275	1.80 (1.33–2.42), p < 0.001

The analytic sample included 9000 participants, comprising 520 exclusive e-cigarette users, 6748 never users, and 1732 exclusive cigarette smokers. The outcome was self-reported respiratory wheezing in the past 12 months. Odds ratios (ORs) are presented with 95% confidence intervals. The final model additionally adjusted for second-hand smoke exposure. Model fit statistics for the final model: McFadden’s pseudo-R² = 0.284; likelihood ratio χ² = 2228.86, p< 0.001.