The Impact of Smoking History on Baseline Characteristic in Patients With Severe Asthma in the German Asthma Net (GAN)

BACKGROUND: Patients with asthma with >10 pack-years are frequently excluded from asthma trials. Little is known about how smoking affects their characteristics and therefore may impact treatment choices. OBJECTIVE: To evaluate the impact of cumulative smoking history on the characteristics of patients with severe asthma. METHODS: We analyzed pulmonary function tests, asthma control, exacerbation rate, and biomarkers. We compared active and ex-smokers (=ever-smokers) versus never-smokers and performed linear models for 3 groups stratified by smoking history (<10 pack-years [py], 10-20 py, and >20 py). Data were obtained from the severe asthma registry German Asthma Net. RESULTS: We included 2478 patients: 65 (2.6%) active smokers, 1005 (40.6%) ex-smokers, and 1408 (56.8%) never-smokers. Of the 1070 ever-smokers, 529 patients (21.3%) had <10 py, 304 (12.3%) 10-20 py, and 237 (9.6%) >20 py. Cumulative smoking history was associated with worse asthma control (>20 py: Asthma Control Test -1.76 [-2.76; -0.77] points [P < .001]; mini-Asthma Quality of Life Questionnaire -0.31 [-0.53; -0.10] points [P = .004]), whereas exacerbation rate and maintenance oral corticosteroid (OCS) doses were similar (P = .13 and P = 1.0). Cumulative smoking history was associated with smoking-related lung injury, for example, diffusing capacity for carbon monoxide (-0.37 mmol/min/kPa for 10-20 py [P = .014], respectively, -0.92 for >20 py [P < .001]), but forced expiratory volume in 1 second (FEV1) and FEV1 reversibility were similar. Cumulative smoking history was furthermore associated with 0.84 [0.73; 0.97]-fold lower fractional exhaled nitric oxide (FeNO) concentrations (P = .007), whereas blood eosinophil count and IgE levels were comparable (BEC: P = 1.0 and IgE: P = .49). CONCLUSIONS: Cumulative smoking history in patients with asthma is associated with worse disease control, lower FeNO levels, and smoking-related lung injuries. Despite these differences, key asthma characteristics such as BEC, IgE, OCS dose, and exacerbation rates remain similar. If thoroughly examined and selected, patients with >10 py may also qualify for targeted treatments.

• Biener, L.
• Stoshikj, S.
• Brugger, J.
• Krall, C.
• Buhl, R.
• Hamelmann, E.
• Korn, S.
• Taube, C.
• Milger, K.
• Schulz, C.
• Suhling, H.
• Jandl, M.
• Ehmann, R.
• Schmidt, O.
• Idzko, M.
• Skowasch, D.