Chronobiology and the short-term effect of air pollution on stroke incidence

Ambient air pollution is a well-known risk factor for cardiovascular disease, but data on its impact on stroke incidence, temporal variation, and mortality are limited. We aimed to investigate the association between short-term exposure to major air pollutants and incidences of stroke in north-eastern Poland. Our second purpose was to assess the association between incidence and mortality of stroke and the seasons, months, days of the week, and its correlation with particulate matters (PMs) concentrations.


What were the results on air pollution and stroke incidence?


Mean PM2.5 concentrations were 19.09 µg/m3, PM10 26.66 µg/m3, CO 0.35 µg/m3. Increase in 10 µg/m3 of PM2.5 and PM10 was related with increase in stroke frequency on the day of the exposure (OR=1.075, 95% CI 0.999-1.157, p=0.053; OR=1.056, 95% CI 1.004-1.110, p=0.035) and the impact on the stroke occurrence even a few times higher (PM2.5: OR=1.120, 95% CI 1.013-1.237, p=0.026; PM10: OR=1.103, 95% CI 1.028-1.182, p=0.006). On the other hand, increase in 1ug/m3 of CO was related with lower stroke occurrence on LAG 2 (OR=0.976, 95% CI 0.953-0.998, p=0.037) and higher on LAG 3 (OR=1.026, 95% CI 1.004-1.049, p=0.022).


What were the results regarding chronobiology?


The highest number of strokes was observed in the winter season comparing to other seasons (p<0.01). The months with the highest stroke percentage were January 1.5/day (N=479) and February 1.49/day (N=419). Additionally, the daily distribution of stroke admissions was observed with the highest frequency on Mondays and Wednesdays in opposition to the weekend (p<0.01). On days with exceeded PM2.5 norms (1.37/day, N=2282 vs. 1.26/day, N=2301; p<0.01) and PM10 concentration significantly more strokes were noted 1.45/day (N=571) vs. 1.30 (N=4065; p<0.03) and higher in-hospital mortality.


What are the main findings from both analyses?


In the studied region besides PMs, the short-term influence of CO on stroke occurrence was observed. The effect was noted up to 3 days after exposure. The stroke occurrence and mortality rate were significantly greater in the winter season. The highest and the lowest frequencies of stroke incidence occurred at the beginning of the week and on weekends, respectively. Exceeded daily PMs concentration norms were associated with more admissions and a worse prognosis.

Our work was presented at 8th European Stroke Organisation Conference (ESOC) 2022.

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