The prognostic impact of smoking and BMI in interstitial lung diseases: real-world data from primary care.

<bold>Objectives:</bold> To detect the impact of the principal clinical, demographic, and anthropometric parameters on survival from the three main fibrosing interstitial lung diseases (ILDs) categories, using primary care data from the Optimum Care Patient Research Database (OPCRD). <bold>Methods:</bold> We extracted incident cases of hypersensitivity pneumonitis (HP), connective tissue disease related ILDs (CTD-ILDs), and idiopathic pulmonary fibrosis (IPF) for the years 2000-2023. We used the Cox regression to calculate crude and mutually adjusted hazard ratios for mortality. We adjusted the analysis for age, sex, ethnicity, smoking status, and body mass index (BMI). <bold>Results:</bold> We extracted 39,007 incident ILD cases between 2000 and 2023 from the OPCRD (n=5,037 HP, n=10,422 CTD-ILDs, n=23,548 IPF). We found that both a low baseline BMI, and obesity were related with a worse prognosis. Either current or ex-smokers had a poorer survival compared with non-smokers. We did not detect any impact of ethnicity on ILDs survival (Table 1). We obtained substantially overlapping results also analysing each ILD category separately. <bold>Conclusion:</bold> Low baseline BMI and obesity stand out as modifiable prognostic factors, offering insights for primary care interventions. Furthermore, the observed impact of smoking status underscores the importance of targeted interventions and smoking cessation programs in managing ILDs.