Trajectory analyses for associations of long-term exposure to air pollution with incident cardiopulmonary diseases, and death: A cohort study of UK Biobank

Although air pollution has been reported to be related to cardiopulmonary diseases, the evidence available for the effects on multimorbidity progression across different stages was unclear. Based on 273,388 residents from the UK biobank, we carried out the multistate model to explore the relations of long-term exposure to air pollution with hazard ratios (HRs) of transitions among respiratory diseases, ischemic heart disease (IHD)and death, and mediation analyses to assess the role of intermediate diseases played in such associations. During a median follow-up of 10.8 years, 11,774 participants had first respiratory diseases, of which 1,268 (10.77%) developed IHD, and 15,002 had first IHD, of which 1,336 (8.91%) developed respiratory diseases. PM_2.5, NO₂, and NO_X were consistently and significantly associated with the risk of transitions from baseline to respiratory diseases and IHD, from respiratory diseases to IHD and death, from IHD to respiratory diseases and death, particularly among overweight and obese adults. The strongest risk for IHD subsequently progressing respiratory diseases was observed with HRs (95% CI) of 1.160 (1.069, 1.259), 1.173 (1.073, 1.283), 1.123 (1.047, 1.205) whereby an interquartile range increased in PM_2.5, NO₂, and NO_X, respectively. Furthermore, intermediated diseases were partially involved in the association of air pollution with subsequent diseases and death. Accordingly, our findings provided evidence of positive and dose-responsive associations of air pollution and risk of multiple transitions among cardiopulmonary diseases, and death, particularly for IHD subsequently developed respiratory diseases, which suggesting more attention ought to pay for a far-profound influence of air pollution on respiratory and cardiovascular diseases.