Temperature decline is a trigger of subarachnoid hemorrhage: case-crossover study with distributed lag model.

The aim was to use a novel statistical test to predict the trend of subarachnoid hemorrhage (SAH) incidence in response to temperature change and demonstrate its delayed effect in a short hazard period.In a retrospective study, data collected between January 2005 and September 2019 were analyzed and 1682 consecutive SAH patients from one hospital were enrolled. Meteorological data in this period including temperature, atmospheric pressure, and humidity were obtained from the China Surface Meteorological Station. Using a case-crossover analysis and distributed lag linear model (DLM) with 4 days lag period to assess the association of temperature change from the previous day (TCP) and risk of SAH. Results were presented as overall cumulative odds ratios (ORs) and 95% CI.Temperature decline was associated with increased risks of SAH: overall cumulative OR was 1.14 (95% CI: 1.05-1.23) for -1.1°C; 2.11 (95% CI: 1.37-3.25) for -6.2°C, as compared with a reference TCP of 0°C. Temperature decline on the day of SAH onset was significantly associated with SAH incidence days, ORs 1.34 (95% CI: 1.19-1.52). In addition, December, ORs 1.49 (95% CI: 1.17-1.90) in winter was the ictus peak in Rizhao throughout the year.Temperature decline from the previous day is a trigger for the occurrence of SAH. Its effect was most apparent on the day of exposure.