Relationship between Out-of-Hospital Cardiac Arrests and COVID-19 During the First and Second Pandemic Wave: It All Depends on the COVID-19 Incidence

Background: it is unknown if a correlation between the OHCA and COVID-19 daily incidence is present both during the first and second pandemic wave at a provincial level. Methods: We considered all the OHCAs occurred in the provinces of Pavia, Lodi, Cremona, Mantua and Varese, in Lombardy Region (Italy), from 21/02/2020 to 31/12/2020. We divided study period into period 1, the first 157 days after the outbreak and including the first pandemic wave (21/02/2020-26/07/2020) and period 2, the second 158 days including the second pandemic wave (27/07/2020-31/12/2020). We calculated the cumulative, daily and 7-days incidence of OHCA and COVID-19 expressed per 100,000 inhabitants for the whole territory and for each province separately for both periods. Findings: A significant correlation between the daily incidence of COVID-19 and the daily incidence of OHCA was observed both during the first and the second pandemic period in the whole territory (R=0.4, p<0.001 for period 1 and 2) and only in those provinces in which the cumulative incidence of COVID-19 overcame those of the whole territory (period 1: Cremona R=0.3, p=0.001; Lodi R=0.4, p<0.001; Pavia R=0.3; p=0.01; period 2: Varese R=0.4, p<0.001). Interpretation: Our results highlight how the COVID-19 burden in a given area could impact on the OHCAs occurrence. Our results stress the importance of strictly monitoring the pandemic trend to predict which territories will be more likely to experience an OHCA increase. That could serve as a guide to re-consider the pre-hospital resources allocation and tailored information campaigns in the future pandemic waves. Trial Registration: Lombardia Cardiac Arrest Registry (Lombardia CARe: NCT03197142) Funding Statement: Lombardia CARe is partially funded by the Fondazione Banca del Monte di Lombardia. Dr Baldi’s salary was partially funded by grant 733381 from the European Union Horizon 2020 Research and Innovation Program of ESCAPE-NET Declaration of Interests: None to disclose. Ethics Approval Statement: It was approved by the Ethical Committee of the Fondazione IRCSS Policlinico San Matteo (proc. 20140028219), where the registry is hosted, and by all the others involved in the territory.