Impact of weather conditions on the development of subarachnoid hemorrhage: A retrospective analysis

Background

Subarachnoid hemorrhage (SAH) is a serious emergent condition. Studies investigating the climatic characteristics at the time of onset or immediately after onset, rather than on the day of onset, are scarce.

Aim

We aimed to clarify the climatic characteristics involved in the development of SAH by analyzing emergency transport data from Kochi Prefecture.

Methods

Emergency transport data from 2015 to 2021 were extracted from the emergency medical and regional disaster information system. The control group was selected from a database of traffic accident cases with sudden onset. First, a logistic regression analysis was performed on SAH and control groups to examine the factors affecting the development of SAH. Second, a matched case-control study and conditional logistic regression analysis were performed.

Results

A total of 272,634 patients were transported during the study period. Of these, 848 were in the SAH group. In the logistic regression analysis, temperature at onset, relative humidity at onset, temperature decrease from the previous day (TDP) post 1, and temperature change from the previous day (TCP) post 1 influenced the onset of SAH. After matching for sex, age, month of onset, time of onset, and transporting fire department in the SAH and control groups, only temperature at onset affected SAH onset. Conditional univariate analysis with temperature at onset as a quintile showed that SAH incidence increased approximately 2.0-fold with cooler temperatures.

Conclusion

We found that lower temperature at onset was a significant climatic characteristic involved in the onset of SAH in Kochi Prefecture.