Environmental Tobacco Smoke and Asthma Exacerbations
Environmental Tobacco Smoke and Asthma Exacerbations
Table 1 displays participants' demographic, socioeconomic and asthma control characteristics. Participants reported an average of 2.3 exacerbations in the previous year. Most participants had mild or moderate persistent asthma and 63.3% had access to at least one asthma controller medication (Table 1).
Participants excluded due to missing key data (n=76) or extremely large number of reported exacerbations (n=4) were not significantly different from the study sample in race/ethnicity, household income, reported household smoking, BMI category or asthma severity. Excluded participants were significantly more likely to be in the youngest (8–9 years) and oldest (14–15 years) age categories (χ=7.94, df=3, p=0.047).
About half (50.4%) of caregivers reported that at least one household member smoked. Participants had a mean cotinine level of 1.44 ng/ml; 69.3% had a cotinine level ≥1, consistent with ETS exposure. Participants with caregiver-reported household smoking had significantly higher cotinine levels than those without caregiver-reported household smoking (geometric mean cotinine level 2.00 vs 1.07, p<0.001). Characteristics of participants with ETS exposure by report or by cotinine level are shown in Table 2.
In multivariable analysis, cotinine was significantly associated with increased exacerbations (incidence rate ratio (IRR)=1.39, 95% CI 1.08 to 1.78) (Table 3), independent of potential confounders. In an identically specified model that included reported smoking in place of cotinine, reported smoking was not significantly associated with exacerbation frequency (IRR=1.04, 95% CI 0.83 to 1.31) (Table 3).
In a multivariable ordered logit regression to predict asthma severity levels, there was no significant association between salivary cotinine and asthma severity, although the CI is in the direction of a positive association (OR 1.47; 95% CI 0.91 to 2.38) (Table 3). When reported household smoking was used to predict asthma severity, we found no significant association between reported smoking and asthma severity (OR 0.90; 95% CI 0.63 to 1.3) (Table 3).
Results
Participant Characteristics and Asthma Symptoms
Table 1 displays participants' demographic, socioeconomic and asthma control characteristics. Participants reported an average of 2.3 exacerbations in the previous year. Most participants had mild or moderate persistent asthma and 63.3% had access to at least one asthma controller medication (Table 1).
Participants excluded due to missing key data (n=76) or extremely large number of reported exacerbations (n=4) were not significantly different from the study sample in race/ethnicity, household income, reported household smoking, BMI category or asthma severity. Excluded participants were significantly more likely to be in the youngest (8–9 years) and oldest (14–15 years) age categories (χ=7.94, df=3, p=0.047).
Tobacco Exposure
About half (50.4%) of caregivers reported that at least one household member smoked. Participants had a mean cotinine level of 1.44 ng/ml; 69.3% had a cotinine level ≥1, consistent with ETS exposure. Participants with caregiver-reported household smoking had significantly higher cotinine levels than those without caregiver-reported household smoking (geometric mean cotinine level 2.00 vs 1.07, p<0.001). Characteristics of participants with ETS exposure by report or by cotinine level are shown in Table 2.
Asthma Exacerbations and Tobacco Exposure
In multivariable analysis, cotinine was significantly associated with increased exacerbations (incidence rate ratio (IRR)=1.39, 95% CI 1.08 to 1.78) (Table 3), independent of potential confounders. In an identically specified model that included reported smoking in place of cotinine, reported smoking was not significantly associated with exacerbation frequency (IRR=1.04, 95% CI 0.83 to 1.31) (Table 3).
Asthma Severity and Tobacco Exposure
In a multivariable ordered logit regression to predict asthma severity levels, there was no significant association between salivary cotinine and asthma severity, although the CI is in the direction of a positive association (OR 1.47; 95% CI 0.91 to 2.38) (Table 3). When reported household smoking was used to predict asthma severity, we found no significant association between reported smoking and asthma severity (OR 0.90; 95% CI 0.63 to 1.3) (Table 3).
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