Background and purpose: Several studies have suggested that exposure to "triggers," could precipitate the onset of ischemic stroke (IS). We performed a systematic review of the potential triggers of IS.
Methods: Two independent reviewers identified studies published between January 1980 and June 2010 from MEDLINE and Embase. Where appropriate, odds ratios (ORs) were combined.
Results: A total of 26 studies identified 12 potential triggers. Twenty-two studies used a case-control design, and hazard period durations ranged from 2 hours to 3 months. The majority of studies were dedicated to alcohol abuse (n = 10) and clinical infection (n = 12). There was a significant association between IS and alcohol abuse of > 40 to 60 g within the preceding 24 hours (OR = 2.66; 95% CI, 1.54 to 4.61) or > 150 g within the previous week (OR = 2.47; 95% CI, 1.52 to 4.02) and infection within the previous week (OR = 2.91; 95% CI, 1.41 to 6.00) or within the previous month (OR = 2.41; 95% CI, 1.78 to 3.27). Other triggers have been far less investigated. There was a significant association between IS and anger, heavy eating, negative or positive emotions, sudden posture change in response to a startling event, birthday, and psychological distress and no significant association with drug abuse or heavy physical exertion. Regarding methodological issues, patients were rarely blinded to study objectives, and interviewers were rarely blinded to patient status.
Conclusions: Research on triggers of IS has been mainly focused on acute alcohol abuse and clinical infection. More research is needed on factors such as physical exertion or acute stress. Future studies should use more appropriate designs and examine different hazard periods.