Aeromedical retrieval diagnostic trends during a period of Coronavirus 2019 lockdown

Background: We aimed to compare the pre, lockdown, and post-lockdown aeromedical retrieval (AR) diagnostic reasons and patient demographics during a period of Coronavirus 2019 (COVID-19) social isolation. Methods: An observational study with retrospective data collection, consisting of Australians who received an AR between the 26 January to the 23 June 2020. The main outcome measures were patient diagnostic category proportions and trends prior (28 January to 15 March), during (16 March to 4 May), and following (5 May to 23 June 2020) social isolation restrictions. Results: There were 16981 ARs consisting of 1959 (11.5) primary evacuations (PE) and 12724 (88.5) inter-hospital transfer (IHT), with a population median age of 52 years old (interquartile range [IQR] 29.0 69.0), with 49.0% (n= 8283) of the cohort being male and 38.0% (n= 6399) being female. There were a total of 6 confirmed and 209 suspected cases of COVID-19, with the majority of cases (n=114; 53.0%) in the social isolation period. As compared to pre-restriction, the odds of retrieval for the restriction and post-restriction period differed across time between the major diagnostic groups. This included, an increase in cardiovascular retrieval for both restriction and post-restriction periods (OR 1.12 95% CI 1.02 1.24 and OR 1.18 95% CI 1.08 1.30 respectively), increases in neoplasm in the post restriction period (OR 1.31 95% CI 1.04 1.64), and increases for congenital conditions in the restriction period (OR 2.56 95% CI 1.39 4.71). Cardiovascular and congenital conditions had increased rates of priority 1 patients in the restriction and post restriction periods. There was a decrease in endocrine and metabolic disease retrievals in the restriction period (OR 0.72 95% CI 0.53 0.98). There were lower odds during the post-restriction period for a retrievals of the respiratory system (OR 0.78 95% CI 0.67 0.93), and disease of the skin (OR 0.78 95% CI 0.6 1.0). Distribution between the 2019 and 2020 time periods differed (p<0.05), with the lockdown period resulting in a significant reduction in activity. Conclusion: The lockdown period resulted in increased AR rates of circulatory and congenital conditions. However, this period also resulted in a reduction of overall activity, possibly due to a reduction in other infectious disease rates, such as influenza, due to social distancing.