Association between quantity and duration of snowfall and risk of myocardial infarction

Abstract

BACKGROUND: Although aggregate data suggest a link between snowfall and myocardial infarction (MI), individual risk has yet to be assessed. We evaluated the association between quantity and duration of snowfall and the risk of MI using nonaggregated administrative health data. METHODS:We used a case-crossover study design to investigate the association between snowfall and hospital admission or death due to MI in the province of Quebec, Canada, between November and April during 1981-2014. The main exposure measures were quantity (in centimetres) and duration (in hours) of snowfall by calendar day. We computed odds ratios (ORs) and 95% confidence intervals (CIs) for the association between daily snowfall and MI, adjusted for minimum daily temperatures. RESULTS:In all, 128 073 individual hospital admissions and 68 155 deaths due to MI were included in the analyses. The likelihood of MI was increased the day after a snowfall among men but not among women. Compared with 0 cm, 20 cm of snowfall was associated with an OR of 1.16 for hospital admission (95% CI 1.11-1.21) and 1.34 for death (95% CI 1.26-1.42) due to MI the following day among men. Corresponding ORs among women were 1.01 (95% CI 0.95-1.07) and 1.04 (95% CI 0.96-1.13). Similar but smaller associations were observed for snowfall duration (0 h v. 24 h) and MI. INTERPRETATION:Both the quantity and duration of snowfall were associated with subsequent risk of hospital admission or death due to MI, driven primarily by an effect in men. These data have implications for public health initiatives in regions with snowstorms.

The eco–biological–behavioural perfect storm that follows heavy snowfall

“…1 In a linked research study, Auger and colleagues have used routinely collected data to determine an association between the quantity and duration of snowfall and the risks of acute myocardial infarction (MI) in Quebec, Canada, between 1981 and 2014. 6 Their findings add weight to our understanding that the act of snow shovelling in cold temperatures sets the stage for an eco-biological-behavioural "perfect storm," particularly among those physically deconditioned who have or who are at risk of heart disease. 3,7 Auger and colleagues' elegant study incorporates detailed region-specific weather conditions, including daily snowfall and temperature, with individual-level data on hospital admissions and vital statistics.…”

Response to “It’s not just the snow; it’s also the cold”

“…Liu and colleagues analyzed count data using an ecologic method. As outlined in our paper, 3 the results from such approaches should be interpreted with caution because of the risk of ecologic bias owing to an inability to account for temporal trends. 4 Consider the possibility that both temperature and incidence of MI hospital admission changed over time for unrelated reasons.…”

The cardiovascular risk of snowfall and snow shovelling in Canada

“…1 The major findings of their work using a large database from Quebec (administrative data) were that the quantity and duration of snowfall were associated with subsequent risk of hospital admission or death due to myocardial infarction, driven primarily by an effect in men.…”

“…Logistic regression did not show any significant group differences in age and known coronary artery disease; however, those who experienced a snow-shovelling-related event were 3.6 times more likely to have a family history of premature cardiovascular disease (p = 0.001) and were 4.8 times more likely to be male (p = 0.01) ( Table 1); 2 the latter in concordance with the study by Auger and colleagues. 1 Those taking more than four cardiovascular medications seemed to be protected, maybe because it had been previously recommended that they avoid this physical activity.…”