Association between rapid weather changes and incidence of chiefly cardiovascular complaints in the emergency department

Abstract

Introduction

Studies suggest that there is an association between weather and cardiovascular disease (CVD) related visits in emergency departments (ED).

Methods

We used a case-crossover study design to investigate the association between ED visits for CVD and changes in temperature, atmospheric pressure, and relative humidity. Patient and weather data from the years 2014 and 2015 were used to investigate relevance of changes associated with weather in the frequency of CVD-related ED visits. They were correlated to overall variability of the visits adjusted to day of the week.

Results

In the study period 20,558 ED visits were related to CVD (mean per day: 28.3). Significant associations were identified for all three variables (temperature, atmospheric pressure, and relative humidity). Significant odds ratio (OR) was found for a large decrease in temperature 1.29 (95%-CI, 1.1–1.52). However, the related effects, although significant, were small compared to overall variability of visits.

Conclusion

We found an association between rapid weather changes on the day before ED admission and ED visits due to CVD. In conclusion, a drop in temperature and an increase or decrease in atmospheric pressure and relative humidity are associated with a slight increase in CVD admissions. However, the observed significant effects seem to be too small to draw any conclusions in terms of ED capacity due to weather changes.

Introduction

Cardiovascular disease (CVD) is a major social and health issue because it is still a leading cause of morbidity and mortality worldwide. The effect of seasonal variation in mortality from coronary artery disease was reported over 80 years ago [26]. Seasonal shift and variations in weather changes and in morbidity and mortality due to CVD have been investigated in several countries with differing climatic conditions. Overall, findings have been inconsistent.

Studies have demonstrated variations in CVD with respect to season and time of day [2,15,25,28,[36], [37], [38],40]. Changes in temperature and atmospheric pressure display daily and seasonal variations and could modulate the occurrence of vascular events [4,19,28,32,35]. For example, a number of studies showed that cold temperature is associated with a more frequent occurrence of myocardial infarction (MI) due to physiological changes (e.g., increase in plasma viscosity and serum cholesterol levels, blood pressure, sympathetic nerves activities, and platelet aggregation) [16,17,23,29,30]. Heat exposure is also well known to be associated with physiological changes (e.g., increased heart rate, blood viscosity, and coagulation) [20,23]. In 2014, Brightwell et al. [5] reported that an elevated risk of acute abdominal aortic aneurysm rupture was associated with changes in temperature and, in 2015, Rakers et al. [33] reported that rapid weather changes are associated with an increasing risk for ischemic strokes. Recently, Mohammad et al. showed in a large, nationwide study (Sweden) that low air temperature was associated with risk of MI. [28]. When reaching the hospital, many of these patients are admitted to emergency departments (ED) for immediate diagnosis and therapy and to determine further treatment strategy. However, for a single ED it is not clear whether changes in the weather are indeed relevant and should be considered, for example, by changing staffing or by modifying treatment protocols.

In recent years the number of interdisciplinary ED in hospitals in Germany has increased. Leipzig University Hospital also established a central ED in 2012. The Leipzig University Hospital is a 1350-bed, primary (highest-level) hospital in the central region of Germany and 36,000 patients are treated annually at the ED there.

The aim of this retrospective, single-center study was to evaluate whether rapid changes in weather conditions (temperature, atmospheric pressure, and relative humidity) are associated with a higher rate of ED admissions for CVD. Furthermore, the observed effects sizes were correlated with the overall variability of visits to the ED adjusted by day of the week in order to assess the relevance of the findings.