Influence of Seasonal Changes on Emergency Transports for Vertigo/Dizziness: A Study Based on Emergency Triage and Weather Factors.

Background: We investigated the association between the number of patients presenting to an emergency room (ER) with vertigo/dizziness (V/D) and seasonal variations, monthly trends, and weather factors.

Methods: We retrospectively investigated age, sex, cause of V/D, emergency triage level (Japan Triage and Acuity Scale), month, and seasonality among patients with V/D transported to the ER of Nippon Medical School between October 2014 and September 2017. We examined weather data, including monthly average precipitation and humidity, with respect to the number of patients with V/D.

Results: Among 706 patients with V/D, 481 presented with vertigo and 225 with dizziness. The mean age was 59±18 years and 66% were female. Regarding triage level, emergent (level 2) and urgent (level 3) cases accounted for 86% of cases and were more frequent in June-September (p=0.012). Regarding seasonality, 158 (22%), 195 (28%), 183 (26%), and 170 (24%) patients presented in spring, summer, autumn, and winter, respectively (p=0.744). The monthly number of V/D emergency transports tended to be higher between June and October and was significantly associated with average temperature (r=0.648, p=0.023), precipitation (r=0.655, p=0.021), humidity (r=0.676, p=0.016), and vapor pressure (r=0.648, p=0.023).

Conclusions: Although no apparent seasonality was observed in the monthly number of V/D-related emergency transports, the emergency triage level increased from the rainy season to early autumn. The monthly number of V/D cases transported by emergency services was significantly associated with average temperature, precipitation, humidity, and vapor pressure. These findings could inform public health policy and increase emergency preparedness.