Residential greenness and incident idiopathic pulmonary fibrosis: A prospective study

Background: The impact of residential greenness on incident idiopathic pulmonary fibrosis (IPF) is unknown. We aimed to assess the association between residential greenness and incident IPF, identify underlying pathways, and further evaluate the effect among different genetic subgroups. Methods: 469,348 participants in the UK Biobank were included and followed until December 2020. Normalized difference vegetation index (NDVI) within 300-, 500-, 1000-, and 1500-m buffers (NDVI300m, NDVI500m, NDVI1000m, and NDVI1500m) were employed as indicators of greenness. The polygenic risk score (PRS) was constructed based on 13 independent SNPs. Cox models were fitted to assess the association of residential greenness with incident IPF. Casual mediation analyses were applied to evaluate potential mediators. Findings: After a median follow-up of 11.85 years, 1574 IPF cases were identified. We found residential greenness inversely associated with incident IPF. The HRs (95%CIs) for each interquartile increase of NDVI300m, NDVI500m, NDVI1000m, NDVI1500m were 0.93 (0.87, 0.99), 0.92 (0.86, 0.98), 0.89 (0.83, 0.95), and 0.89 (0.83, 0.95), respectively. The association was stronger among individuals with intermediate or high genetic risk. In mediation analyses, the main mediators identified were PM2.5 and NO2, with proportion mediated estimated to be 31.92% and 40.61% respectively for NDVI300m. Interpretation: Residential greenness was associated with reduced risk of incident IPF.