Abstract Body: Background: Prior research has shown that acute particulate matter (PM) exposure may be associated with neurotoxicity and increased incidence of stoke. However, few studies have examined the progression of stroke outcomes in the early time course from onset. The aim of this study is to examine the effect of ambient PM 1 week prior to stroke onset on early clinical outcomes.
Methods: This is a secondary analysis of the “Field Administration of Stroke Therapy-Magnesium” (FAST- MAG), randomized, placebo-controlled, clinical trial of prehospital-initiated magnesium sulfate in stroke patients between 2005 and 2013 in Los Angeles and Orange Counties. We utilized geospatial coding based on patients’ home address to assign average corresponding PM_2.5 and PM₁₀ levels one week prior to stroke. We studied early post-emergency department (ED) arrival NIH Stroke Scale (NIHSS), prehospital and early post-ED arrival dichotomized Glasgow Coma Scale (GCS=15 Y/N), prehospital and early post-ED arrival Los Angeles Motor Scale (LAMS). Relationships were assessed using linear or logistic regression adjusting for age, sex, ethnicity, medical history, smoking, alcohol and time from onset to ED.
Results: A total of 1450 patients were included for whom we were able to assign residential PM exposures at the time of index stroke. For each 10ug/m³ increase in PM_2.5 we observed a 0.2-point higher LAMS at hospital arrival (p=0.02) and 55% lower odds of GCS-15 at Day 4 (p<0.001). Each 10ug/m³ increase in PM₁₀ was associated with 37% lower odds of GCS-15 at Day 4 (p=0.045). In a subgroup of patients with acute cerebral ischemia (n=1095), a 10ug/m³ increase in PM_2.5 was associated with a 0.15-point higher prehospital LAMS (p=0.048), and a 0.3-point higher LAMS at hospital arrival (p=0.012).
Conclusions: Among patients with cerebral ischemia, exposure to greater increased ambient PM within one week prior to index stroke was associated with worse presenting stroke severity and with in-hospital deterioration in level of consciousness. These findings suggest that efforts to reduce PM air pollutant exposures may reduce the presenting severity and early progression of acute cerebral ischemia.