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 2N†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% CIAdjusted coefficient§95% CI
Past 30-day tobacco use
 Combustible versus non-combustible tobacco use
  Never used tobacco24423.523.5RefRef
  Formerly used tobacco42823.323.40.06−0.36 to 0.48
  Non-combustible use only4422.9¶22.4¶−0.58−1.86 to 0.70
  Any combustible use61022.422.6−0.04−0.46 to 0.38
 Specific tobacco products used
   Yes42823.323.40.07−0.33 to 0.47
   Yes48222.122.40.03−0.43 to 0.49
   Yes25122.522.6−0.11−0.55 to 0.33
   Yes13722.522.90.26−0.17 to 0.69
   Yes17422.322.3−0.42−0.96 to 0.13
   Yes7723.122.9−0.06−0.73 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)
13260.00−0.05 to 0.040.00−0.05 to 0.05
 Past-month marijuana use**
  Yes31922.622.8−0.02−0.36 to 0.330.01−0.34 to 0.37
Relevant medical history
 ACT score at wave 213260.530.45 to 0.620.530.44 to 0.62
 Body mass index
  Underweight3923.3¶22.9¶−0.39−1.37 to 0.59−0.39−1.39 to 0.61
  Overweight36123.123.1−0.17−0.49 to 0.14−0.19−0.51 to 0.13
  Class 1 obese20623.023.0−0.17−0.64 to 0.30−0.17−0.64 to 0.29
  Class 2+ obese21122.622.6−0.38−1.03 to 0.27−0.39−1.03 to 0.25
 P12M asthma controller medications††
  Yes14020.220.21.47−2.40 to –0.541.49−2.42 to –0.57
  Male59923.423.50.370.09 to 0.650.370.07 to 0.67
  No high school degree15322.222.1RefRefRefRef
  GED6022.421.9−0.23−1.13 to 0.67−0.23−1.14 to 0.67
  High school grad29022.722.70.41−0.25 to 1.080.4−0.27 to 1.07
  Some college54223.123.10.56−0.05 to 1.170.57−0.05 to 1.19
  ≥College graduate28123.623.80.860.10 to 1.620.870.10 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.