Table 5

Weighted prospective associations between wave 2 past 30-day tobacco use and wave 3 Asthma Control Test (ACT) score among adults aged 18–39 years at wave 2 of the PATH Study, controlling for wave 2 ACT score, negative coefficients reflect worsening of asthma symptoms over time*

Risk factor at wave 2	N†	Mean wave 2 ACT score‡	Mean wave 3 ACT score‡	How tobacco use is modelled
				Model 1 Combustible versus non-combustible tobacco use		Model 2 Specific tobacco products used
				Adjusted coefficient§	95% CI	Adjusted coefficient§	95% CI
Past 30-day tobacco use
Combustible versus non-combustible tobacco use
Never used tobacco	244	23.5	23.5	Ref	Ref	–	–
Formerly used tobacco	428	23.3	23.4	0.06	−0.36 to 0.48	–	–
Non-combustible use only	44	22.9¶	22.4¶	−0.58	−1.86 to 0.70	–	–
Any combustible use	610	22.4	22.6	−0.04	−0.46 to 0.38	–	–
Specific tobacco products used
Former
No	898	22.9	23.0	–	–	Ref	Ref
Yes	428	23.3	23.4	–	–	0.07	−0.33 to 0.47
Cigarette
No	844	23.4	23.4	–	–	Ref	Ref
Yes	482	22.1	22.4	–	–	0.03	−0.43 to 0.49
Cigar
No	1075	23.2	23.2	–	–	Ref	Ref
Yes	251	22.5	22.6	–	–	−0.11	−0.55 to 0.33
Hookah
No	1189	23.1	23.1	–	–	Ref	Ref
Yes	137	22.5	22.9	–	–	0.26	−0.17 to 0.69
E-cigarette
No	1152	23.2	23.2	–	–	Ref	Ref
Yes	174	22.3	22.3	–	–	−0.42	−0.96 to 0.13
Smokeless
No	1249	23.1	23.1	–	–	Ref	Ref
Yes	77	23.1	22.9	–	–	−0.06	−0.73 to 0.61
Other smoke-related exposures
Cigarette pack-years (per each 5 pack-years)	1326	–	–	−0.10	−0.36 to 0.16	−0.09	−0.35 to 0.18
Past-week SHS exposure (per each 5 hours/week)	1326	–	–	0.00	−0.05 to 0.04	0.00	−0.05 to 0.05
Past-month marijuana use**
No	1007	23.2	23.2	Ref	Ref	Ref	Ref
Yes	319	22.6	22.8	−0.02	−0.36 to 0.33	0.01	−0.34 to 0.37
Relevant medical history
ACT score at wave 2	1326	–	–	0.53	0.45 to 0.62	0.53	0.44 to 0.62
Body mass index
Underweight	39	23.3¶	22.9¶	−0.39	−1.37 to 0.59	−0.39	−1.39 to 0.61
Normal	509	23.3	23.5	Ref	Ref	Ref	Ref
Overweight	361	23.1	23.1	−0.17	−0.49 to 0.14	−0.19	−0.51 to 0.13
Class 1 obese	206	23.0	23.0	−0.17	−0.64 to 0.30	−0.17	−0.64 to 0.29
Class 2+ obese	211	22.6	22.6	−0.38	−1.03 to 0.27	−0.39	−1.03 to 0.25
P12M asthma controller medications††
No	1186	23.4	23.5	Ref	Ref	Ref	Ref
Yes	140	20.2	20.2	−1.47	−2.40 to –0.54	−1.49	−2.42 to –0.57
Sociodemographics
Sex
Female	727	22.8	22.8	Ref	Ref	Ref	Ref
Male	599	23.4	23.5	0.37	0.09 to 0.65	0.37	0.07 to 0.67
Education
No high school degree	153	22.2	22.1	Ref	Ref	Ref	Ref
GED	60	22.4	21.9	−0.23	−1.13 to 0.67	−0.23	−1.14 to 0.67
High school grad	290	22.7	22.7	0.41	−0.25 to 1.08	0.4	−0.27 to 1.07
Some college	542	23.1	23.1	0.56	−0.05 to 1.17	0.57	−0.05 to 1.19
≥College graduate	281	23.6	23.8	0.86	0.10 to 1.62	0.87	0.10 to 1.64

Online supplemental table 12 reports SEs for all the weighted estimates presented in this table and adjusted coefficients for all the variables in the model.
*N=1326 wave 2 adult (age 18–39) respondents with valid wave 2 and wave 3 ACT scores, without chronic obstructive pulmonary disease or other non-asthma respiratory diseases at waves 2–4, with wave 4 PATH Study longitudinal (all waves) weights, and complete data on all analytical variables.
†Unweighted.
‡ACT scores can range from 5 to 25. A higher ACT score represents more controlled asthma.
§All (unstandardised) coefficients adjust for the variables in the table plus age, race/ethnicity and lives in an urban area. Bold coefficients are statistically significant at p<0.05.
¶Estimate should be interpreted with caution because it has low statistical precision. It is based on a denominator sample size of less than 50, or the coefficient of variation of the estimate or its complement is larger than 30%.
**Marijuana use variable does not distinguish between combustible and non-combustible use.
††P12M use of asthma controller medication(s).
GED, General Education Development (high school equivalency certificate); PATH, Population Assessment of Tobacco and Health; P12M, past-12 month; SHS, secondhand smoke.