- Cardiovascular disease admissions decreased by 32% on high snowfall days but increased by 23%, two days after.
- Admissions for falls increased 18% on average during the six days following a moderate snowfall.
- Cold-weather-related disease admissions increased by 3.7% on high snowfall days compared to days with no snowfall.
More frequent snowfall is expected with global climate change. But evidence regarding their impact on health, hospital admissions are limited.
A new study led by researchers from Harvard T.H. Chan School of Public Health assessed data for 433,037 adults hospitalized at the four largest hospitals in Boston (Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Boston Medical Center, and Massachusetts General Hospital) during the months of November through April, for the years 2010-2015.
‘Snow shoveling results in significant increases in heart rate, systolic blood pressure, and rate-pressure product which may trigger an acute cardiac event, particularly in those with underlying coronary artery disease.’
"This was a complex data science endeavor that required coordination and linkage of electronic medical records across hospitals," said senior author Francesca Dominici, professor of biostatistics and senior associate dean for research at Harvard Chan School.
They focused on admissions for cardiovascular diseases; cold-weather related conditions such as frostbite; and falls and injuries.
Health hazards posed by snowfalls may have previously been unrecognized, according to the researchers. A possible explanation could be that people who are most susceptible to cardiovascular events and falls stay indoors during heavy snowfalls and avoid potential hazards, say the researchers.
The results show that on high snowfall days (>10.0 inches of snow), cardiovascular disease admissions decreased by 32% but increased by 23%, two days after. The two-day delayed jump in admissions for cardiovascular events after heavy snowfalls could reflect delays getting to the hospital during snow emergencies.
Cold-related admissions increased by 3.7% on high snowfall days and remained high for 5 days after. Admissions for falls increased by 18% on average in the 6 days after a moderate snowfall day (5.1 - 10.0 inches).
The mechanisms by which snowstorms lead to adverse cardiovascular events that are not fully understood, noted the authors. Snow shoveling may be one such factor.
This possibility derives from prior studies of "snow-shoveler's infarction," which found that heavy snow shoveling resulted in cardiorespiratory demands that were comparable to or higher than the demands of maximal treadmill testing.
Snow shoveling results in significant increases in heart rate, systolic blood pressure, and rate-pressure product which may trigger an acute cardiac event, particularly in those with underlying coronary artery disease.
Jennifer Bobb, Lead author, Group Health Research Institute in Seattle, said, "Understanding trends in hospitalizations related to snowfall will help us develop ways to protect public health during harsh winter conditions."
- Jennifer F.Bobb et al., Time-Course of Cause-Specific Hospital Admissions During Snowstorms: An Analysis of Electronic Medical Records From Major Hospitals in Boston, Massachusetts, Am J Epidemiol (2017)
- Rajesh Janardhanan et al.,The Snow-Shoveler's ST Elevation Myocardial Infarction, American Journal of Cardiology (2010), 10.1016/j.amjcard.2010.03.075.