# Air temperature and humidity impact out-of-hospital-cardiac-arrests in Germany: A 10-year cohort study from the German Resuscitation Registry

## TL;DR

This study finds that cold and high-humidity days in Germany are linked to higher rates of out-of-hospital cardiac arrests over a 10-year period.

## Contribution

The study provides new evidence linking environmental factors like cold and humidity to increased cardiac arrest incidence in Germany.

## Key findings

- Frost days are associated with a significant increase in out-of-hospital cardiac arrests (6.39 to 7.00 per 100,000 inhabitants).
- High-humidity days show a statistically significant rise in cardiac arrest incidence (6.43 to 6.89 per 100,000 inhabitants).
- Cold and high-humidity days correlate with worse outcomes and cardiac-related causes of cardiac arrests.

## Abstract

This study examines the impact of temperature variations on out-of-hospital-cardiac-arrests in Germany over a decade (2010–2019). Out-of-hospital-cardiac-arrests affects 164 per 100,000 inhabitants annually in Germany, 11% survive to hospital discharge. The following study investigates days with the following characteristics: summer days, frost days, and high humidity days. Furthermore, the study explores incidence, causes, demographics, and outcomes of out-of-hospital-cardiac-arrests.

Data from the German Resuscitation Registry and Meteorological Service were combined for analysis. The theory posits that temperature and humidity play a significant role in the occurrence and outcomes of out-of-hospital-cardiac-arrests, potentially triggering pre-existing health issues.

Findings reveal increased out-of-hospital-cardiac-arrests during frost days (6.39 up to 7.00, p < 0.001) monthly per 100,000 inhabitants), notably due to cardiac-related causes. Conversely, out-of-hospital-cardiac-arrests incidence decreases on summer days (6.61–5.79, p < 0.001 monthly per 100,000 inhabitants). High-humidity days exhibit a statistically significant increase in out-of-hospital-cardiac-arrests incidence (6.43–6.89, p < 0.001 monthly per 100,000 inhabitants).

In conclusion, there’s a notable rise in out-of-hospital-cardiac-arrests incidence and worse outcomes during cold days, and a significant increase in out-of-hospital-cardiac-arrests during high-humidity days. Moreover, extreme temperature events in unaccustomed regions also elevate out-of-hospital-cardiac-arrests rates. However, the dataset lacks sufficient hot days for conclusive findings, hinting that very hot days might also affect out-of-hospital-cardiac-arrests incidence. Further research, particularly on hotter days, is essential.

No third-party funding was received for this study.