Triggers of Ischemic Stroke: Results from the Stroke Onset Pilot Study

P153 Despite progress in the identification of risk factors for stroke, relatively little is known about the immediate precipitants or triggers of acute ischemic stroke (IS). We therefore conducted a pilot study to determine the presence of potential triggers within 24 hours preceding the onset of IS to establish the feasibility of conducting a case-crossover study of potential triggers of IS. The case-crossover design is an epidemiologic method that uses each patient as his/her own control, developed to evaluate the effect of potential triggers on the incidence of acute events. During the time of the pilot, we recruited 50 patients (88% of all eligible hospitalized patients) mean age 62±16 years, including 32% women. Patients were typically interviewed in hospital within 2 or 3 days of the onset of IS. The structured interview covered use of medications, caffeinated beverages, alcohol, smoking behavior, illicit drugs including marijuana and cocaine, timing of meals particularly unusually large meals, episodes of straining for defecation or urination, sexual intercourse and heavy physical exertion. Separate questions emphasized lifting heavy objects, and psychometric evaluations of anger, anxiety and depression. Large vessel atherothrombotic lesions were responsible for 39% of strokes, cardioembolic sources for 28%, small vessel disease (lacunar infarcts) for 22%, and other etiologies for 11%. The prevalence of exposure in the year prior to stroke varied from 10% for marijuana to 88% for caffeinated beverages. Exposure to potential triggers in the 24 hours before stroke onset was reported in over 30% of cases, including heavy exertion ≥ 6 METs (8%), lifting ≥ 50lbs (10%), straining for urination or defecation (4%), sexual intercourse (2%), outbursts of anger (4%), alcohol (28%), and marijuana (6%). The Stroke Onset Study Pilot demonstrates that potential triggers are present in approximately one-third of patients with IS. A larger study is required to assess whether external stressors can trigger the onset of stroke. Identifying and understanding the mechanisms by which particular exposures trigger the onset of stroke may lead to novel preventive strategies.