Smoking is associated with poor symptom control and impaired therapeutic responses in asthma. A total of 843 patients with asthma were recruited. The patients received treatment for 1 yr according to the severity of their asthma. We compared the forced expiratory volume in 1 sec (FEV1), the ratio of FEV1 to forced vital capaity (FVC), atopy, total IgE, emphysema on high-resolution computed tomography (HRCT), the number of near-fatal asthma attacks, and physiological fixed airway obstruction between the smoking and nonsmoking groups. The study population consisted of 159 (18.8%) current smokers, 157 (18.7%) ex-smokers, and 525 (62.5%) nonsmokers. Although the prevalence of atopy was not different between the smoking and nonsmoking groups, the total IgE was higher among the smokers than the nonsmokers. Compared with the nonsmoking group, the smokers had a lower FEV1 % predicted and forced expiratory flow between 25 and 75% of FVC. A greater prevalence of emphysema and a significantly higher number of asthmatic patients with fixed airway obstruction were detected in the smoking versus nonsmoking group. The 37.5% of asthmatic patients who were former or current smokers showed decreased pulmonary function and increased IgE, emphysema on HRCT, and fixed airway obstruction, indicating that smoking can modulate the clinical and therapeutic responses in asthma.
Airway Obstruction/etiology ; Asthma/complications/*diagnosis/*drug therapy ; Female ; Forced Expiratory Volume/physiology ; Humans ; Immunoglobulin E/analysis ; Male ; Middle Aged ; Pulmonary Emphysema/etiology/radiography ; Respiratory Function Tests ; Respiratory Insufficiency/etiology ; Smoking/*adverse effects ; Tomography, X-Ray Computed

BACKGROUND: Bronchial asthma is a clinical syndrome characterized by reversibility of airway obstruction. However, many asthmatics have evidence of residual airway obstruction. It has become evident that the repair of the chronic inflammatory process can lead to various irreversible changes. It is generally accepted that the most common cause for the change is cigarette smoking but it is controversial whether asthma progresses to emphysema. High resolution computed tomography (HRCT) is more sensitive and more accurate than chest plain films in determining the type and extent of emphysema. This study was carried out to determine whether asthma can be a cause of emphysema without the effect of cigarette smoking and to evaluate clinical characteristics in asthmatics with emphysema. METHODS: We studied 58 asthmatic patients with reversible airway obstruction and evaluated the presence of emphysema using HRCT and pulmonary function test. According to HRCT findings, they were divided into 2 groups : Asthmatics with emphysema and the ones without emphysema. REWSULTS: Of the 58 patients, 7 were revealed to have emphysema. (1) 6 asthmatics with emphysema were smokers, but one patient was a nonsmoker. (2) Highly significant differences between asthmatics with and without emphysema were found in cigarette smoking (p< 0.01) and smoking consumption (p< 0.01). (3) There were no significant differences in the duration of asthma, age or sex between patients with and without emphysema. (4) There were no significant differences in FEV1(%), FEV1/FVC (%), diffusing capacity for carbon monoxide (DLco) (%) and DLco/alveolar volume between patients with and without emphysema (5) Differences between asthma patients without emphysema and those with emphysema were found to be significant in bronchial wall thickeness (p< 0.05) and in total Ig E levels (p=0.07). CONCLUSION: These results indicate that smoking is a main factor in causing emphysema in asthmatics.
Adolescent ; Adult ; Aged ; Asthma/*complications/physiopathology/radiography ; Comparative Study ; Female ; Human ; Male ; Middle Age ; Pulmonary Emphysema/*etiology/physiopathology/radiography ; Respiratory Function Tests/statistics & numerical data ; Smoking/adverse effects ; Tomography, X-Ray Computed/methods

Adult ; Age Factors ; Aged ; Chronic Disease ; Electrocardiography ; Female ; Humans ; Lung Diseases, Obstructive ; diagnostic imaging ; etiology ; Male ; Middle Aged ; Prospective Studies ; Pulmonary Emphysema ; etiology ; Radiography ; Respiratory Function Tests ; Sex Factors ; Smoking