Relationships of active smoking to asthma and asthma severity in the EGEA study

Abstract

The role of smoking as potential risk factor, selection factor (“healthy smoker” effect) and modifying factor (severity) of asthma was studied in the Epidemiological study on the Genetics and Environment of Asthma, bronchial hyperresponsiveness and atopy (EGEA). The analysis involved 200 adult asthmatic cases recruited in chest clinics, 265 nonasthmatic controls and 586 relatives of asthmatics (147 with asthma). Asthma in childhood was not associated with a reduced take‐up of smoking (odds ratio (OR)=1.06 in males and 0.98 in females), but smoker asthmatic cases quit more often than controls (OR = 2.20 (95% confidence interval (95% CI) 1.11‐4.34) in males and 2.76 (1.19–6.42) in females). Adult onset asthma was unrelated to ever smoking (OR 1.07 in males and 1.02 in females). In asthmatic cases, active smoking was associated with asthma severity. Current smokers, compared to never and exsmokers, had more asthma symptoms, more frequent (≥1 attack·day‐1) asthma attacks (OR 2.39 (95% CI 1.06–5.36)) and higher asthma severity scores. No clear pattern regarding the relationships of smoking habits with asthma was observed in first degree relatives. It is concluded that active smoking is not a risk factor for asthma in adulthood, but that smoking increases asthma severity.

What lies behind relief and worsening of asthma symptoms? A register-based study of adults with asthma and other chronic obstructive pulmonary diseases in Finland

“…It seems that latent COPD did not significantly interfere with the results. Our results give support to earlier reports [5][6][7][8][9].…”

“…The greater alleviation of asthma symptoms among non-smokers is understandable, since smoking directly affects asthmatic symptoms [5,6] and the development of COPD [14]. Tobacco smoke can also affect symptoms by altering the response to inhaled corticosteroids [15].…”

“…A quarter of the smokers reported symptom relief, but current smoking appeared to protect men against a worsening of asthma. One explanation may be that individuals with a less sensitive bronchial tract emerge as smokers in the long term [5].…”

“…Inhaled corticosteroids play a major part in this [1,2], but environmental circumstances [3,4], smoking [5,6] and psychosocial and emotional factors [7][8][9] may also have an effect on the frequency of symptoms.…”

A prospective study of asthma incidence and its predictors: the RHINE study

“…Conversely, active smokers seem to have more severe asthma than nonsmokers [25]. This observation is also supported by a case study in which cigarette smoking is associated with more severe asthma [26]. Hence, the use of self-reported asthma may overestimate the asthma risk among smokers, because self-reported asthma probably is biased in relation to disease severity.…”