Psychosocial stress tied to daily myocardial infarction rates
Periods of presumed psychosocial stress are correlated with daily fluctuations in myocardial infarction rates, a new study from Sweden has found.
The study included 156,690 myocardial infraction events (mean age of patients 71.8±12.4 years; 63.7 percent male) grouped according to specific time period and days. Holidays (n=9,835), turns of the month (n=41,246) and Mondays (n=25,338) were all presumed to increase stress; while summers (n=11,935) and weekends (n=40,225), decrease stress.
After adjusting for the whole population, daily myocardial infarction rates were found to be significantly higher during holidays (incidence rate ratio [IRR], 1.07; 95 percent CI, 1.04 to 1.09; p<0.001) and Mondays (IRR, 1.11; 1.09 to 1.13; p<0.001) and significantly lower during summer (IRR, 0.92; 0.90 to 0.94; p<0.001) and weekends (IRR, 0.88; 0.87 to 0.89; p<0.001).
Contrary to what was hypothesized, turns of the month (IRR, 1.01; 1.00 to 1.02; p=0.891) did not correlate significantly with higher daily myocardial infarction rates. Additionally, daily temperatures showed a significant negative association with myocardial infarction rates (IRR per 10oC increase, 0.98; 0.97 to 0.99; p<0.001).
Subgroup analyses also showed that the increase in adjusted daily myocardial infarction rates was higher in males (IRR, 1.14; 1.12 to 1.16; p<0.001) than in females (IRR, 1.06; 1.04 to 1.09; p<0.001), and in working adults (IRR, 1.20; 1.16 to 1.24; p<0.001) than in pensioners (IRR, 1.08; 1.07 to 1.11; p<0.001).
In contrast, the effect of holidays on myocardial infraction rates was significant in pensioners (IRR, 1.09; 1.07 to 1.12; p<0.001) but not in working adults (IRR, 0.99; 0.93 to 1.04; p=0.599).