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 Prevalence of Asthma and Smoking1
In 2001, 7.9% of the adult population in Oregon reported that they currently have asthma (CI 7.0, 8.8). Prevalence is significantly lower for men (5.6%; CI 4.5, 6.7) than for women (10.2%; CI 8.9, 11.6). Compared to adults without asthma, a higher proportion of Oregon adults with asthma smoke (23 vs. 31%, p<.05).
This finding is consistent with at least one other very large cross-sectional study. In our study, nearly twice as many heavy smokers (those who smoke one or more packs a day) reported having asthma compared to those who have never smoked. Figure 1 reveals that this relationship is particularly pronounced for women who are heavy smokers — they were two and a half times more likely to report having asthma than women who have never smoked (p<.05). The aforementioned cross-sectional study also noted a trend of asthma prevalence increasing for women in proportion to the number of cigarettes smoked per day, but not for men.Whether these data represent true prevalence differences between men and women, or represent gender bias in diagnosing is not known.
 However, new research indicates that women?s lungs may be more susceptible to the harmful effects of smoking than men?s. Could the relationship between smoking and asthma really be due to other differences between smokers and nonsmokers, such as income? To answer this question, multiple logistic regression was used to analyze the independent relationships of gender, income, smoking status, and body mass index (wt/ht2) to having current asthma. Risk factors that had independent and significant relationships to current asthma were heavy smoking (OR 2.0; 1.3, 3.2), female gender (OR 2.2; 1.6, 3.0) and obesity (OR 2.7; 1.9, 3.7).
Income appeared to have no independent relationship to asthma. While smoking is known as a potent asthma trigger, obesity appears to be even more strongly related to asthma. Stay tuned for an upcoming View of Asthma in Oregon on this topic.
1. The Behavioral Risk Factor Surveillance System (BRFSS) is a random-digit-dialed cross-sectional telephonic survey administered every year in the state of Oregon to adults aged 18 and older. In 2001, over 6,000 Oregonians participated in the survey, reporting on their own health behaviors, health conditions, and demographic profiles.Analyses in this publication focus only on adults up to 55 years old to mitigate the potential effects of comorbidity with chronic obstructive pulmonary disease (COPD).
Data presented in this publication have been weighted to represent the population of Oregon. Initial data analyses were performed in SPSS 11.0 for point estimates, and in Stata 7.0 for statistical tests. Differences between variables were analyzed by two-tailed Student?s t-tests. All p-values reported as p<.05 are statistically significant, and confidence intervals (CI?s) are reported at the 95% level.
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