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Seasonal variation in stroke mortality rates
1Veterans Affairs Medical Center, Tomah, WI 54660, USA.
Neurology
|April 2, 1999
Summary
Seasonal variations in stroke mortality are linked to respiratory illnesses and colder temperatures. Higher rates of stroke and respiratory disease deaths occur during winter months, influenced by temperature and illness severity.
Area of Science:
- Environmental epidemiology
- Public health research
- Biostatistics
Background:
- Analysis of US vital statistics and census data (1938-1988) for stroke and respiratory disease mortality.
- Utilized state-specific monthly average temperatures (1938-1987) from the National Climatic Data Center.
Purpose of the Study:
- To investigate factors contributing to seasonal fluctuations in stroke mortality.
- To understand the relationship between temperature, respiratory diseases, and stroke deaths.
Main Methods:
- Time series decomposition to isolate trend, seasonal, and residual effects.
- Multiple regression analysis to model seasonal harmonic series.
- Cross-correlation analysis to examine relationships between residual time series.
Main Results:
- Consistent seasonal pattern observed, with elevated stroke and respiratory disease mortality during winter.
- Stroke mortality showed significant positive association with respiratory disease mortality and inverse association with temperature.
- Synchronous increases in respiratory disease and stroke mortality in late fall/early winter, with strong amplitude association.
Conclusions:
- Seasonal changes in stroke mortality are significantly associated with variations in respiratory disease and ambient temperature.
- Respiratory disease and temperature may nonspuriously influence stroke mortality by affecting case fatality or incidence.