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 26 January and 23 June 2020. The main outcome measures were patient diagnostic category proportions and trends prior (28 January to 15 March), during (16 March to 4May), and following (5 May to 23 June 2020) social isolation restrictions. Results There were 16981 ARs consisting of 1959 (11.5) primary evacuations (PEs) and 12724 (88.5) inter-hospital transfers (IHTs), with a population median age of 52 years (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 six 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. #### What is already known on this subject What is already known on this subject We know the rates of Coronavirus 2019 (COVID-19) have an impact on a range of health services globally, however we do not have a clear understanding of the aeromedical retrieval reasons during a period of sustained social isolation. #### What this study adds What this study adds While there were fewer aeromedical retrievals during the social isolation period there were relatively more retrievals for cardiovascular disease and congenital malformations of the circulatory system. However, post-restriction demonstrated reductions in respiratory disease and skin infections, as compared to the pre-restriction period. Many aeromedical retrievals come from areas with higher chronic disease rates. If these areas have community transmission of COVID-19, it is likely that retrievals will increase for severe COVID-19 patients, with associated comorbidities such as cardiovascular disease. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement No external funding was received ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This project was deemed a low-risk quality assurance project by the RFDS Clinical and Health Services Research Committee (CHSRC), which provides oversight for RFDS research projects. As this project involved routinely collected data, specific patient consent forms were not required. All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Upon request.