Abdurrahman KOÇ, Abdullah Enes ATAŞ, Hasan ERYEŞİL
Anatolian Current Medical Journal - 2026;8(3):560-568
Aims: To determine whether active smokers with preserved post-bronchodilator spirometry (FEV?/FVC >= lower limit of normal [LLN]) and normal thoracic computed tomography (CT) show lower FEF????? values and a higher prevalence of isolated small airway dysfunction than never-smokers, and to assess PEF-FEV? agreement for Global Initiative for Chronic Obstructive Lung Disease (GOLD) severity staging. Methods: We analysed spirometry data from 286 consecutive adults (>=40 years) at a single pulmonary function laboratory. Two chest radiologists independently reviewed all thoracic CT scans (ICC=0.95). Logistic regression included FVC z-score as a pre-specified covariate to account for the volume-dependence of FEF??-??; model stability was confirmed by penalised regression and bootstrap validation. Results: Among 244 participants with preserved FEV?/FVC (136 smokers, 108 never-smokers), FEF????? was lower in smokers (76.2+/-26.1% vs 93.5+/-21.9%; p<0.001; rank-biserial r=0.40). Isolated Spirometric small airway dysfunction (sSAD) prevalence was 28.7% versus 4.6% (OR 8.28; p<0.001). After FVC z-score adjustment, smoking remained the strongest predictor (aOR 13.15; 95% CI 4.07-42.42; optimism-corrected AUC=0.848). Female smokers showed greater impairment than males despite equivalent pack-year exposure (66.3% vs 80.9%; p<0.001), and combined biomass-plus-smoking exposure carried the highest sSAD prevalence (58.1%). PEF showed poor agreement with FEV? for GOLD staging (unweighted kappa=0.095; mean bias -20.0%). Conclusion: Active smoking is independently associated with spirometric small airway dysfunction before FEV?/FVC falls below the LLN, with women and biomass co-exposed individuals at greatest risk. PEF cannot replace FEV? for GOLD severity classification in this population.
