From: Longitudinal association of exclusive and dual use of cigarettes and cigars with asthma exacerbation among US adults: a cohort study
Number of follow-up waves
No. (%)a
(N = 2,883)
95% CI
0
1865 (64.2)
61.8–66.6
1
519 (18.7)
16.7–20.9
2
249 (8.3)
7.1–9.6
3
159 (5.8)
4.8–7.0
4
91 (3.0)
2.2–4.0