The study by Auger and colleagues in CMAJ showed that the amount and duration of snowfall was associated with an increased risk of admission to hospital and death due to myocardial infarction (MI) among men from Quebec, Canada.1 The study apparently did not adjust by barometric pressure; if the data are available, does the inclusion of barometric pressure have a confounding effect or effect modification on the estimates? Some studies have shown that changes in barometric pressure are associated with MI and coronary deaths.2–4
In the historic snowstorm that hit the eastern United States in January of 1978, barometric pressure in some cities dropped as low as 40 millibars in 24 hours. A blizzard is distinctive because of the fast drop in barometric pressure in a 24-hour period. Three days after the storm of 1978, admissions for MI, total mortality and ischemic heart disease deaths increased in Rhode Island for the five-day period following the blizzard; however, the effect of barometric pressure was not assessed in that study and the blizzard was considered the only culprit.5
A recent Asiatic study found that extreme ambient temperatures were associated with cardiorespiratory mortality. An interesting finding was the decrease of cold effect on mortality by 2.36% associated with an increase in barometric pressure, indicating that it may have an impact on the effect of other weather variables on mortality.6 Furthermore, there is evidence of a positive correlation between barometric pressure and blood oxygen saturation.7 Patients with MI or ischemic heart disease are particularly susceptible to changes in blood oxygen saturation.
Footnotes
Competing interests: None declared.