Page 131 - ADULT-ONSET ASTHMA PREDICTORS OF CLINICAL COURSE AND SEVERITY

PREDICTORS FOR THE DEVELOPMENT OF PROGRESSIVE SEVERITY IN NEW-ONSET ADULT ASTHMA
DISCUSSION
This prospective cohort study shows that in adults with new-onset asthma the only independent predictor for an increase in asthma severity within 2 years a er diagnosis is a posi ve smoking history. Even a limited number of pack years of cigare e smoking is associated with increased risk for asthma deteriora on, whereas in ammatory parameters, lung func on, sex, BMI and sinonasal symptoms are not predic ve for worsening of early asthma. These results suggest that previous smoking is the most important factor in uencing asthma severity in adult-onset asthma.
To our knowledge this is the rst prospec ve longitudinal cohort study that evaluated predictors for asthma deteriora on in adults with new-onset asthma. One previous longitudinal study inves ga ng risk factors of asthma severity was performed in a mixed popula on of pa ents with longstanding childhood- and adult-onset asthma.21 This study showed that pa ents with severe disease at baseline were at risk for severe disease nine years later. Comparison of this study with our study is di cult due to lack of assessment of longitudinal change in asthma severity in the la er study and di erences in pa ent selec on criteria. Our observa on that smoking history predicts deteriora on extends the ndings by Polosa et al.20 They retrospec vely studied pa ents with allergic rhini s who developed asthma within a period of 10 years20 and found that pa ents with more severe asthma had smoked more pack years than those with milder asthma. Our results also extend the results from other longitudinal studies in mixed asthma popula ons looking at components of asthma severity, including asthma exacerba ons and accelerated decline in FEV1.22-26 These studies showed that recent exacerba on history was a strong predictor of future asthma exacerba ons,22 whereas ac ve smoking,23;26 high levels of exhaled nitric oxide24 and in ltra on of CD8+ cells in the airway wall25 were shown to be predictors of accelerated decline in FEV1. All these results provide evidence that a posi ve smoking history in adult pa ents with new-onset asthma is a strong and dose-dependent predictor of an increase in asthma severity over the next 2 years.
The strength of our study is its prospec ve design with extensive baseline assessments to fully characterize the pa ents. Also, the study popula on is unique since all pa ents were recently diagnosed with adult-onset asthma. Smokers and ex-smokers were purposely not excluded from par cipa on into the study as long as they met the stringent diagnos c criteria for asthma. This is important, because most asthma studies exclude smokers or subjects who have smoked >10 pack years, whereas in a large propor on (20-30%) of the actual popula on of asthma pa ents are current smokers.27-29 We avoided including pa ents with “pure” COPD by excluding (ex-)smokers with persistent air ow limita on or reduced di usion capacity, but cannot exclude the inclusion of pa ents with overlap between these diseases.30 Unfortunately, we did not reassess bronchodilator reversibility and di usion capacity at the 2 year follow-
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