Impacts of viral respiratory infections on segments of fatal out-of-hospital cardiac arrests.

Purpose of the study: Viral respiratory infections have been linked to fatal out-of-hospital cardiac arrest (OHCA), yet the specific causes remain unclear, and the impact of individual viral infections is often confounded by local meteorological and environmental factors. This study aimed to investigate the independent effects of prevalent viral respiratory infections on the risk and causes of fatal OHCA in different age groups.

Study design: We conducted negative binomial regression analyses to investigate the association between influenza, respiratory syncytial virus (RSV), and coronavirus disease 2019 (COVID-19) infections, along with temperature, extreme weather alerts, and the air quality health index, with age- and cause-specific fatal out-of-hospital cardiac arrest (OHCA) from the 2nd week of 2014 to the 17th week of 2020. The analysis covered three etiological categories (cardiovascular, respiratory, and non-cardiovascular non-respiratory) across three age groups (≤ 64 years, 65-84 years, ≥ 85 years) in Hong Kong.

Results: During this period, there were 41 548 fatal OHCA cases in Hong Kong. Influenza was consistently associated with fatal OHCA across all etiologies and age groups, significantly impacting cardiovascular and non-cardiovascular non-respiratory causes more than respiratory causes (110.9, 66.8, and 17.4 per 1 million persons, respectively). Reduced healthcare-seeking behaviors during the COVID-19 pandemic was linked to increased fatal OHCA across all ages and etiologies, except for respiratory causes. RSV showed no association with fatal OHCA in our population.

Conclusions: Influenza is a significant independent risk factor for fatal OHCA across variouscauses and age groups, particularly affecting cardiovascular and non-cardiovascular non-respiratory outcomes.