Ambient Temperature and Stroke Occurrence: A Systematic Review and Meta-Analysis

Abstract

Biologically plausible associations exist between climatic conditions and stroke risk, but study results are inconsistent. We aimed to summarize current evidence on ambient temperature and overall stroke occurrence, and by age, sex, and variation of temperature. We performed a systematic literature search across MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, and GEOBASE, from inception to 16 October 2015 to identify all population-based observational studies. Where possible, data were pooled for meta-analysis with Odds ratios (OR) and corresponding 95% confidence intervals (CI) by means of the random effects meta-analysis. We included 21 studies with a total of 476,511 patients. The data were varied as indicated by significant heterogeneity across studies for both ischemic stroke (IS) and intracerebral hemorrhage (ICH). Pooled OR (95% CI) in every 1 degree Celsius increase in ambient temperature was significant for ICH 0.97 (0.94–1.00), but not for IS 1.00 (0.99–1.01) and subarachnoid hemorrhage (SAH) 1.00 (0.98–1.01). Meta-analysis was not possible for the pre-specified subgroup analyses by age, sex, and variation of temperature. Change in temperature over the previous 24 h appeared to be more important than absolute temperature in relation to the risk of stroke, especially in relation to the risk of ICH. Older age appeared to increase vulnerability to low temperature for both IS and ICH. To conclude, this review shows that lower mean ambient temperature is significantly associated with the risk of ICH, but not with IS and SAH. Larger temperature changes were associated with higher stroke rates in the elderly.

Cerebral venous thrombosis, seasonal trends, and climatic influence: A region-specificstudy

“…In a large meta-analysis of 21 studies, a lower mean ambient temperature was significantly associated with the risk of hemorrhagic strokes. [ 14 ] A similar trend was noted in the Intensive Blood Pressure Reduction in Acute Cerebral Haemorrhage Trial (INTERACT2). [ 15 ]…”

Ambient temperature and risk of cardiovascular events at labor and delivery: A case-crossover study

“…The literature generally suggests that exposures to both high and low temperatures are associated with cardiovascular events in non-pregnant populations around the world (Basu, 2009; Bhaskaran et al, 2012; Ha et al, 2014; Honda et al, 2016; Phung et al, 2016; Sartini et al, 2016; Wang et al, 2016; Yang et al, 2015) with potentially higher sensitivity among Blacks women, those with lower socioeconomic status, the elderly, and young children (Basu, 2009); but data among pregnant women are currently lacking. One large international multicenter case-control study among reproductive age women ages 15 to 49 showed that each 5°C decrease in monthly average temperature was associated with a 7% and 12% increase in hospital admission rates for stroke and acute myocardial infarction, respectively; and these effects were more prominent within one month of exposure (Chang et al, 2004).…”

“…The week prior to delivery and the days comprising the week prior to delivery were chosen as the hazard periods given evidence suggesting acute cardiovascular effects within seven days in the non-pregnant population (Dahlquist et al, 2016; Wang et al, 2016; Wichmann et al, 2013; Zheng et al, 2016). Temperature during this hazard period was then compared to two control periods: the second week after delivery and the week two full gestational weeks before delivery.…”

“…Studies have linked extreme ambient temperatures with acute cardiovascular risk in the general population as well as in susceptible subgroups including those with lower socioeconomic status, the elderly, and those with other comorbid conditions (Medina-Ramon and Schwartz, 2007; Wang et al, 2016; Yang et al, 2015). A role for temperature in the pathogenesis of cardiovascular risks is plausible given the oxidative stress and systemic inflammation induced shortly after exposure (Cai et al, 2016; Cheng et al, 2015; Halonen et al, 2010; Hong et al, 2012; Quindry et al, 2013).…”

Association Between Stroke Occurrence And Changes In Atmospheric Circulation 

“…During the recent decade, many studies have focused on the impact of weather on the morbidity from stroke, and several meta-analyses or reviews were carried out [1][2][3][4][5]. Air temperature (T) and atmospheric pressure (AP) are among the most closely studied weather variables; increases, decreases, and uctuations in both have been signi cantly linked to numerous stroke subtypes.…”