OC 72.3 - Risk of pulmonary embolism and deep vein thrombosis associated with short-term air pollution

Background: It is uncertain whether air pollution is associated with short-term risk for venous thromboembolism (VTE).

Aims: Report the change in odds of VTE—defined as lower extremity deep vein thrombosis (DVT) and pulmonary embolism (PE) identified on imaging reports by natural language processing (NLP)—associated with exposure to particulate matter ≤2.5 µm in aerodynamic diameter (PM2.5) overall, and during wildfire season (June-October) and inversion season (November-March), respectively.

Methods: 25,560 VTE cases were identified by NLP between 1 January 2008 and 31 March 2022 in the electronic health record among non-hospitalized residents of Utah’s Wasatch Front (greater Salt Lake City) who received care from Intermountain Health. The primary statistical analysis of VTE events and ambient PM2.5 was based on a time-stratified case-crossover design that matches exposure at the time of event with ≥1 day when the event did not occur to estimate the potential excess risk using conditional poisson regression. PM2.5 exposure was estimated based on air monitoring at stations along the Wasatch Front with patient PM2.5 exposure attribution assigned to the station nearest the patients’ residence. VTE odds is reported in relation to increased PM2.5 on individual days 0 and 2 before a VTE event and as an antecedent 3-day and 7-day moving average (including the event day).

Results: Nonsignificant negative associations were observed for PM2.5 exposure for VTE at day lag 0 (OR, 0.9968; 95% confidence interval [CI] 0.9747- 1.0193), lag 2 (OR= 0.9735; 95% CI 0.9518- 0.9956), 3-day average (OR= 0.995; 95% CI 0.9693- 1.0212), and 7-day average (OR 1.0073; 95% CI 0.9733- 1.0422) before VTE diagnosis. When separated into wildfire and inversion seasons, and for the outcome of DVT and PE separately similar results were observed (Table).

Conclusion(s): PM2.5 exposure was not associated with an increased risk for VTE, PE, or DVT either overall, or when stratified by wildfire season and inversion season.