Table 3

Weighted prospective associations between wave 2 past 30-day tobacco use and new-onset asthma diagnosis at waves 3 or 4 of the PATH Study*

Risk factor at wave 2	N†	US population %	New-onset asthma diagnosis %	Models predicting asthma
				Model 1 Combustible versus non-combustible tobacco use		Model 2 Specific tobacco products used
				Adjusted RR‡	95% CI	Adjusted RR‡	95% CI
Past 30-day tobacco use
Combustible versus non-combustible tobacco use
Never used tobacco	1755	30.9	0.8§	Ref	Ref	–	–
Formerly used tobacco	2762	33.7	1.1	1.39	0.63 to 3.07	–	–
Non-combustible use only	345	3.1	1.2§	1.55	0.34 to 7.07	–	–
Any combustible use	3973	32.3	1.2	1.27	0.58 to 2.79	–	–
Specific tobacco products used
Former
No	6073	66.3	1.0	–	–	Ref	Ref
Yes	2762	33.7	1.1	–	–	1.36	0.70 to 2.63
Cigarette
No	5652	74.1	1.0	–	–	Ref	Ref
Yes	3183	25.9	1.1	–	–	0.99	0.53 to 1.86
Cigar
No	7464	89.5	1.0	–	–	Ref	Ref
Yes	1371	10.5	1.5	–	–	1.44	0.77 to 2.72
Hookah
No	8000	93.9	1.0	–	–	Ref	Ref
Yes	835	6.1	1.5	–	–	1.35	0.65 to 2.80
E-cigarette
No	7700	90.9	1.0	–	–	Ref	Ref
Yes	1135	9.1	1.3	–	–	1.12	0.50 to 2.51
Smokeless
No	8343	95.7	1.0	–	–	Ref	Ref
Yes	492	4.3	0.9§	–	–	0.97	0.29 to 3.28
Other smoke-related exposures
Cigarette pack-years (per each 5 pack-years)	8835	–	–	1.06	0.83 to 1.37	1.09	0.84 to 1.41
Past-week SHS exposure (per each 5 hours/week)	8835	–	–	0.98	0.91 to 1.06	0.98	0.91 to 1.06
Past-month marijuana use¶
No	6956	85.3	1.0	Ref	Ref	Ref	Ref
Yes	1879	14.7	1.2	1.12	0.68 to 1.84	1.05	0.66 to 1.69
Relevant medical history
Body mass index
Underweight	294	2.9	0.8§	0.82	0.24 to 2.87	0.82	0.24 to 2.83
Normal	3749	40.9	0.8	Ref	Ref	Ref	Ref
Overweight	2510	30.3	0.8	1.11	0.59 to 2.08	1.11	0.59 to 2.09
Class 1 obese	13,03	14.5	1.0	1.30	0.67 to 2.51	1.30	0.67 to 2.52
Class 2+ obese	979	11.4	2.5	3.12	1.67 to 5.86	3.11	1.66 to 5.82

Online supplemental table 10 reports SEs for all the weighted estimates presented in this table and adjusted RRs for all the variables in the model.
*N=8835 wave 2 adult (age 18–39) respondents never diagnosed with asthma, 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.
‡All RRs adjust for the variables in the table plus age, sex, ethnicity/race, education and lives in an urban area. Bold RRs 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.
PATH, Population Assessment of Tobacco and Health; RRs, risk ratios; SHS, secondhand smoke.