Risk factors for airflow obstruction development in an occupational cohort. The value of borderline FEV1/FVC ratio.

<bold>Introduction:</bold> Exposure to dust, gases, or particles in an occupational setting increase the risk of developing airflow obstruction (AO). <bold>Material and methods:</bold> Our Pulmonary Dpt. has been conducting regular medical evaluations to asbestos exposed workers (AEW) (n=1203) since 2000. In a subgroup of healthy AEW, w/ normal lung function and ≥2 annual spirometries, we analyzed AO incidence and risk factors (RF) for its development. <bold>Results:</bold> 485 AEW were included in the analysis (Table 1). Mean follow-up was 152±73 months. Median number of spirometries was 3 (IQR 2-4). 150 AEW developed AO (31% incidence), 36 and 114 in never smokers (NS) and smokers, respectively. Overall, most significant RF for AO were FEV1/FVC:0.70-0.75 (HR 6.19; 95%CI 4.45-8.61; p<0.001), dyspnea mMRC≥2 (HR 1.93; 95%CI 1.12-3.34; p=0.02) and PRISm (HR 3.59; IC95% 2.02-6.40; p<0.001) (Table 1). This pattern remained true in smokers. However, in NS respiratory symptoms (RS) were not associated with increased risk of AO, whereas FEV1/FVC:0.70-0.75 and PRISm were the most significant. In a multivariate model that included the 4 SLIM criteria, only pack-yrs≥30 and FEV1/FVC:0.70-0.75 were significant (HR 4.70; 95%CI 3.10-7.12; p<0.001, for the latter). In another model that included age, sex, pack-yrs, and PRISm, FEV1/FVC:0.70-0.75 still prevailed (HR 3.37; 95%CI 2.25-5.06; p<0.001). <bold>Conclusion:</bold> A FEV1/FVC between 0.70-0.75 is a significant independent RF for AO in both smokers and NS.