Association between winter season and risk of death from cardiovascular diseases: a study in more than half a million inpatients in Beijing, China

Abstract

BackgroundSeasonal associations of cardiovascular mortality have been noted in most populations of European origin years ago, but are not well evaluated in Asian populations recently.MethodsUtilizing the electronic Hospitalization Summary Reports (HSRs) from 32 top-ranked hospitals in Beijing, China, we evaluated the association between winter season and the risk of cardiovascular death among hospitalized individuals. General additive models and logistic regression models were adjusted for confounding factors.ResultsOlder patients who were admitted to the hospital in the winter months (January, February, November and December) had a death risk that was increased by approximately 30% to 50% (P < 0.01) over those who were admitted in May. However, younger patients did not seem to experience the same seasonal variations in death risk. The excess winter deaths among older patients were associated with ischemic heart disease (RR = 1.22; 95% CI 1.13 to 1.31), pulmonary heart disease (RR = 1.42; 95% CI 1.10 to 1.83), cardiac arrhythmias (RR = 1.67; 95% CI 1.36 to 2.05), heart failure (RR = 1.30; 95% CI 1.09 to 1.54), ischemic stroke (RR = 1.30; 95% CI 1.17 to 1.43), and other cerebrovascular diseases (RR = 1.78; 95% CI 1.40 to 2.25). The risks of mortality were higher in winter months than in the month of May, regardless of the presence or absence of respiratory disease.ConclusionsWinter season was associated with a substantially increased risk of cardiovascular death among older Chinese cardiovascular inpatients.

Seasonal effect of vitamin D deficiency in patients with acute myocardial infarction

“…However, it is still not well recognised if there is any relationship between seasonal variation of 25(OH)D levels and the incidence of acute myocardial infarction (AMI) [4]. These associations might explain the observed relationship between the seasonal periodicity of cardiovascular mortality with a winter peak and summer nadir [12,13].…”

The Association Between Acute Myocardial Infarction with Seasonal Variations and Admission Time

“…In some other studies, in addition to the abovementioned effective factors, geographic regions, seasons, and also different hours of a day were recognized as the risk factors. Different statistics regarding death prevalence in many countries and cities in different seasons and hours also confirmed this issue (11)(12)(13)(14).…”

“…Also, in the studies by Heyer and Kloner, MI was more in the warm season (16,21), but in most of the studies, MI was observed in winter. Xu et al, in a study conducted in China reported that 30% to 50% of MIs occurred in winter (12); the studies by Spencer in America (19), Daei in Qazvin, Iran (13), Jahanbakhsh in Ahar, Iran, (7) and Oranto et al, (29) also indicated that MI mostly occurred in winter. Marchant et al, believed that ambient temperature had an important role in the acute MI pathogenesis (11).…”

Features of Seasonal Cardiovascular Mortality in Winter in Russian Regions With Different Climatic and Geographical Characteristics

“…Эта тенденция подтверждена в исследованиях от-дельных стран, например, в Норвегии и Ирландии ян-варь также оказался месяцем с самой большой смерт-ностью в течение года, и при анализе за 10-летний пе-риод показано, что смертность в январе выше, чем смертность в июле в среднем на 22% и 35%, соответ-ственно [17]. При анализе госпитальной летальности в Китае показано, что пожилые пациенты, госпитализи-рованные в зимние месяцы (ноябрь-февраль) харак-теризовались повышенным риском смерти на 30-50% по сравнению с теми, кого госпитализировали в мае [18].…”