Long-term exposure to ambient air pollution is a risk factor for trajectory of cardiometabolic multimorbidity: A prospective study in the UK Biobank

Background: Although air pollution has been frequently linked to a range of cardiometabolic diseases, its association with the onset, progression, and prognosis of cardiometabolic multimorbidity (CMM) has never been studied. Methods: We conducted this prospective analysis based on the UK Biobank cohort. CMM was defined as the coexistence of at least two cardiometabolic diseases, including type 2 diabetes, ischemic heart disease and stroke. Multi-state model was used to analyze the association between air pollution and the trajectory of CMM. Findings: 410,494 middle- and old-age participants were included. During a median follow-up of 12.0 years, 56,877 participants developed first cardiometabolic disease (FCMD), 8616 developed CMM, and 22,423 died. The risks of transitions from baseline to FCMD, from FCMD to CMM, and transitions from baseline and FCMD to all-cause mortality increased by 3% (2%, 5%), 3% (1%, 6%), 5% (2%, 7%) and 2% (−1%, 6%), respectively, per interquartile range increase of fine particulate matter. The corresponding increases were 3% (2%, 5%), 6% (3%, 9%), 4% (2%, 7%) and 6% (2%, 10%), respectively, for nitrogen dioxide. Older participants, males, and individuals with excessive alcohol drinking and lower economic levels were more likely to experience these risks. Interpretation: Air pollution exposures could play important roles in almost all transition phases of CMM development. Our results highlight clean air as an upstream approach to mitigate both initiation and progression of CMM, especially in vulnerable populations. Funding: Shanghai Municipal Science and Technology Commission (21TQ015); The National Natural Science Foundation of China (92143301 and 92043301).