Seasonality and circadian distribution of Sudden death in a University Hospital, Eastern Saudi Arabia

Abstract EN

Objective : seasonal variation in coronary heart disease events including sudden cardiac death has been documented for long time.

Sudden death especially sudden cardiac death peaks in winter, and decreases in summer months.

We promote that the risk for sudden death (SD) in the Eastern Region of Saudi Arabia, significantly increases during the very hot and humid long summer season.

Al Shamal’s (Northern) wind also blow across this region from mid spring to late summer months which is considered to be a major risk for exacerbation of respiratory diseases such as bronchial asthma and chronic obstructive pulmonary disease.

Methods : We retrospectively investigated all deceased cases (1273 cases) that occurred between January 1, 2000 and Dec 31, 2005 (223 cases of sudden death and 1050 of expected death) in King Fahd Hospital of the University (KFHU), with the permissions of the research committees of both the College of Medicine, Dammam University, and KFHU, Al Khobar, Saudi Arabia.

The monthly and seasonal variation and the circadian distribution of sudden death were studied.

The necessary statistical analyses to examine the relationship between variables were implemented and a (p value) of < 0.05 was considered significant.

Results : out of 1273 cases of total death, we identified 223 cases of sudden death and 1050 cases of expected death during the 6 years study period.

There was a seasonal variation in sudden death with higher frequency (54.7 %) occurring in hot, humid, and dusty climate (spring and summer) than (45.3%) in temperate climate (fall and winter), (risk ratio : 1.457, 95 % CI 1.090-1.947 p = 0.012).

Sudden death occurred more frequently in June (11.7 %) when the hot weather is coupled with severe humidity and dust brought on by AL-Shamal (Northern) winds, than in other months (p < 0.0001).

Circadian distribution of sudden death and expected death was also noted with higher frequency in early morning hours (31.38 % and 28.86 % respectively) than other times of the day (p < 0.0001) Conclusions : Hot, humid and dusty climate was associated with higher frequency of sudden death than temperate and cool climate.

There was also a clear circadian distribution of sudden death with higher frequency in the early morning hours.