Effect of seasonal and temperature variation on hospitalizations for stroke over a 10-year period in Brazil

Abstract

Background Seasonal variation in stroke incidence remains controversial. Aims We aimed to describe the pattern of seasonality in hospitalizations for stroke in Brazil. Methods We evaluated age-adjusted hospitalization rates for stroke per month using data from the Brazilian Unified Healthcare System and median monthly temperature data obtained from the National Institute of Meteorology. To detect a seasonality pattern in time series, we used seasonal-trend decomposition using LOESS. We calculated a seasonal strength statistic and used Kruskal–Wallis test to evaluate the presence of seasonality in Brazil and its five regions. We also assessed the association of temperature and stroke hospitalization rates using Spearman’s rho correlation. Results We identified 1,422,496 stroke-related hospitalizations between 2009 and 2018. Mean age was 67 years, 51% were male and 77.5% of stroke diagnoses were not specified as ischemic or hemorrhagic. Median temperature was 23.8℃ (IQR 22.3–24.4). Age-adjusted hospitalizations demonstrated significant seasonal variation during all the years analyzed, with increased rates during the winter. When regional differences were analyzed, seasonal behavior was present in the south, southeast and northeast regions of the country. These were also the regions with lower median temperatures during the winter months and greater amplitude of average temperatures between warmer and colder months. Conclusions In this large national cohort of stroke patients in Brazil, we demonstrated the presence of seasonal variation in the age-adjusted hospitalization rate, with peak rates during the winter months. The regional gradient of incidence of stroke was directly associated with colder winters and greater amplitude of temperature.

Seguimento de pessoas acometidas por doenças cerebrovasculares em um hospital regional amazônico: uma metodologia WHO STEP Stroke

“…A taxa encontrada parece alta em relação à média de hospitalizações por AVC na região Norte e no Brasil (13,0 e 8,8 por 100.000 habitantes, respectivamente). 44 No entanto, devese lembrar que limitações como o baixo número de admissão e o viés de aferição podem estar presentes neste estudo, e tais limitações reduzem o poder de comparabilidade destes dados com os de outros estudos, mesmo para aqueles com metodologias similares.…”

Age-dependent seasonality in the incidence of stroke: A 21-year population-based study

“…Various studies from different regions of the world support a winter peak in the incidence of stroke. [4][5][6][7][8][9][10][11][12] Seasonality in several cardiovascular risk factors may explain this winter peak, specifically in the elderly population. Fibrinogen, for instance, is an independent risk factor for cardiovascular disease.…”

“…3 Seasonal variations in the incidence of stroke have been examined in numerous studies worldwide. Most studies reported a winter peak in the occurrence of stroke, [4][5][6][7][8][9][10][11][12] others found no seasonal variation [13][14][15] and fewer showed a summer peak 16 or an autumn peak. 17 Data on whether seasonality of stroke differs with age are limited.…”

Syphilis and ischemic stroke: Old question revisited by a nationwide cohort study

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