Temporal patterns of stroke onset. The Framingham Study

Area of Science:

• Epidemiology
• Neurology
• Public Health

Background:

• Previous studies indicated seasonal, weekly, and daily variations in stroke onset, primarily from clinical data susceptible to bias.
• Understanding these temporal patterns is crucial for insights into stroke pathogenesis.
• A community-based cohort study is needed to provide a less biased perspective on stroke occurrence.

Purpose of the Study:

• To investigate the temporal patterns of stroke onset, including month, season, day of the week, time of day, and place of occurrence.
• To analyze these patterns in relation to stroke incidence, subtype, and gender within a community-based cohort.
• To identify periods of increased stroke risk for potential preventive strategies.

Main Methods:

• A 40-year surveillance of the Framingham Study cohort (5070 participants aged 30-62) free of stroke and cardiovascular disease at entry.
• Systematic ascertainment of month, season, day of the week, time of day, and place of occurrence for 637 completed initial strokes.
• Prospective analysis relating temporal factors to stroke incidence, subtype, and gender.

Main Results:

• Winter was the peak season for cerebral embolic strokes.
• Mondays showed significantly higher stroke event occurrences than other days, especially for working men; intracerebral hemorrhages also peaked on Mondays.
• Strokes most frequently occurred between 8 AM and noon across all subtypes, even when excluding sleep-related onsets. Hemorrhagic strokes occurred outside the home, and cerebral embolisms occurred more in hospitals.

Conclusions:

• The study identified distinct temporal patterns in stroke onset regarding season, day of the week, time of day, and location within a community-based population.
• These findings highlight specific periods of increased stroke risk.
• The observed patterns suggest potential opportunities for developing targeted preventive strategies.