August 1, 2026Journal of the American College of Cardiology
Increased winter mortality from acute myocardial infarction and stroke: the effect of age
Key result
Winter season is linked to ~9% higher acute myocardial infarction mortality, amplified by older age.
- RR 1.090
- P<0.005
- n=300,000
Why the study?
Does the winter season increase mortality from acute myocardial infarction and stroke across different age groups?
Population
300,000 deaths from acute myocardial infarction and stroke in the Canadian Mortality Database for the years…
Comparison
Winter season (beginning in December) vs Summer season and other months
Design
Cross-sectional
Authors
Discussion
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Implication
Winter is associated with increased mortality from acute myocardial infarction and stroke, with the magnitude of this seasonal variation increasing significantly with advancing age.
Key Points
- This study investigates how age affects seasonal variations in mortality from acute myocardial infarction and stroke.
- Analyzed 300,000 deaths from the Canadian Mortality Database between 1980-1982 and 1990-1992.
- Employed chi-square test for homogeneity at p < 0.01 and calculated relative risk ratios (RRs).
- Reported seasonal mortality differences across four age subgroups (under 65, 65-74, 75-84, and over 85).
- AMI deaths peaked in January (RR = 1.090) and were lowest in September (RR = 0.904), with a relative risk difference of 18.6%.
- Mortality variation for AMI increased with age: 5.8% (<65), 8.3% (65-74), 13.4% (75-84), 15.8% (>85) with p < 0.005 for trend.
- Stroke mortality also peaked in January (RR = 1.113), varying by age: no variation (<65), 11.6% (65-74), 15.2% (75-84), 19.3% (>85) with p < 0.005 for trend.
Study Design
Type
Observational (n=300,000)
Structured PICO
Does the winter season increase mortality from acute myocardial infarction and stroke across different age groups?
P
Population
300,000 deaths from acute myocardial infarction and stroke in the Canadian Mortality Database from 1980-1982 and 1990-1992, analyzed for seasonal variations by age.
E
Exposure
Winter season (beginning in December)
C
Comparator
Summer season and other months
O
Outcome
Seasonal variations in mortality from acute myocardial infarction (AMI) and stroke by agehard clinical
Main Result
Relative Risk: 1.09
p-value: p=<0.005
Winter is associated with increased mortality from acute myocardial infarction and stroke, with the magnitude of this seasonal variation increasing significantly with advancing age.
Cite This Study
Sheth et al. (1999) conducted an observational in Acute myocardial infarction and stroke (n=300,000). Winter season vs. Summer season / overall mean was evaluated on Mortality from acute myocardial infarction (AMI) (RR 1.090, p=<0.005). Winter season was associated with increased mortality from acute myocardial infarction (RR 1.090 in January) and stroke (RR 1.113), with the seasonal variation increasing significantly with age.