Access rate to the emergency department for venous thromboembolism in relationship with coarse and fine particulate matter air pollution

Particulate matter (PM) air pollution has been associated with cardiovascular and respiratory disease. Recent studies have proposed also a link with venous thromboembolism (VTE) risk. This study was aimed to evaluate the possible influence of air pollution-related changes on the daily flux of patients referring to the Emergency Department (ED) for VTE, dissecting the different effects of coarse and fine PM. From July 1(st), 2007, to June 30(th), 2009, data about ED accesses for VTE and about daily concentrations of PM air pollution in Verona district (Italy) were collected. Coarse PM (PM(10-2.5)) was calculated by subtracting the finest PM(2.5) from the whole PM(10). During the index period a total of 302 accesses for VTE were observed (135 males and 167 females; mean age 68.3 ± 16.7 years). In multiple regression models adjusted for other atmospheric parameters PM(10-2.5), but not PM(2.5), concentrations were positively correlated with VTE (beta-coefficient = 0.237; P = 0.020). During the days with high levels of PM(10-2.5) (≥ 75(th) percentile) there was an increased risk of ED accesses for VTE (OR 1.69 with 95%CI 1.13-2.53). By analysing days of exposure using distributed lag non-linear models, the increase of VTE risk was limited to PM(10-2.5) peaks in the short-term period. Consistently with these results, in another cohort of subjects without active thrombosis (n = 102) an inverse correlation between PM(10-2.5) and prothrombin time was found (R = -0.247; P = 0.012). Our results suggest that short-time exposure to high concentrations of PM(10-2.5) may favour an increased rate of ED accesses for VTE through the induction of a prothrombotic state.