Seasonal variation in spontaneous intracerebral hemorrhage in northern Israel

Abstract

The incidence of spontaneous intracerebral hemorrhage (sICH) and ischemic stroke vary across seasons. Most studies examining seasonal variation in sICH have been conducted in countries with significant climatic changes across seasons, whereas studies from the Mediterranean region, which has a relatively mild winter, are limited in number and have produced inconsistent results. Further studies from the region are called for, especially from countries where sICH seasonality has not yet been explored. A total of 974 patients with sICH between 1 January 2000 and 31 December 2014 were included in this study. The seasonal, monthly and weekday distribution of hospital admissions, in-hospital mortality, length of hospital stay and functional outcome at discharge were examined. We found that most hospital admissions due to sICH occurred in the winter (n = 286, 29%), whereas the fewest admissions occurred in the summer (n = 205, 21%; p = 0.0011). In terms of monthly distribution, most admissions were in January (n = 107, 11%), and the fewest admissions were in September (n = 60, 6%; p = 0.0004). There were no differences in the distribution of sICH between weekdays and weekends. Also, we found no significant weekday or seasonal variations in in-hospital mortality or functional outcome of sICH. Our results suggest that temporal patterns impact the natural course of sICH in northern Israel. The identification of factors, including biological ones, responsible for seasonal variation in regions with mild seasonal changes requires further research but could aid in the design of strategies for preventing sICH.

Monthly variance in UK renal transplantation activity: a national retrospective cohort study

“…Although detailed causal analysis was beyond the scope of the study, the winter increases in deceased donation could be attributed to increases in both cerebrovascular and hypoxic brain events. This is consistent with findings from previous studies studying the incidence of these events both in the UK9 and other northern hemisphere countries 11 12…”

“…The donor rates reported in the paper are from used donations, and therefore can be influenced by changes in donor conversion rates; the proportion of donor offers used in a transplant operation. This is unlikely, however, as these changes would have to be consistently occurring in the same way each year for 10 years; furthermore, the peak of deceased donation activity coincided with the epidemiological peaks for the underlying diseases 7–12. Since this was a retrospective study, there is always the potential for inherent bias, but since this is relatively a large data set, it should minimise this effect.…”

“…This can be attributed to the effects of endogenous seasonal rhythms and climatic factors on human performance and activity patterns. In the UK, seasonal variations are commonly observed for infectious diseases, such as influenza,6 cerebrovascular disease7–12 and myocardial infarctions 13. Several studies have recently shown how understanding these oscillations are crucial for planning and delivering optimum healthcare delivery 14.…”

“…Several studies have recently shown how understanding these oscillations are crucial for planning and delivering optimum healthcare delivery 14. For example, the USA covers many different climate zones, but depite this cerebrovascular accidents in the USA peak in the winter15 in a similar pattern to the UK 7–12. Surprisingly, transplant activity in the USA is lowest in the winter months for both renal16 and heart transplantation, despite these deaths being a leading cause of organ donation 17.…”

Dependence of seasonal dynamics of hemorrhagic and ischemic strokes on the climate of a region: A meta-analysis

“…A total of 746 publications were found. For our meta-analysis, 31 publications were selected: 20 publications examining seasonal dynamics of HS and 26 publications examining seasonal dynamics of IS 9–39 (Supplementary Material, Table S1, Figure S1). In 15 studies, the seasonal dynamics of HS and IS were simultaneously investigated.…”