key: cord-301189-6sq1pfo8
authors: Zheng, Hua; Tan, Juan; Zhang, Xianwei; Luo, Ailin; Wang, Liuming; Zhu, Wentao; Hébert, Harry L.; Meng, Weihua; Smith, Blair H.; Colvin, Lesley A.; Hu, Junbo
title: Impact of sex and age on respiratory support and length of hospital stay among 1,792 patients with COVID-19 in Wuhan, China
date: 2020-07-16
journal: Br J Anaesth
DOI: 10.1016/j.bja.2020.07.001
sha: 
doc_id: 301189
cord_uid: 6sq1pfo8

nan

Editor -The coronavirus disease-19 (COVID-19), associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread rapidly since the early cases identified in Wuhan, China. There were over 8,061,550 laboratory-confirmed COVID-19 cases worldwide and 84,867 cases in China as of 18 th June 2020 1, 2 . Among the latter, 19% were severe or critically ill patients who required some form of respiratory support due to hypoxaemia or respiratory failure 3 . The respiratory support included low-flow or high-flow oxygen therapy via nasal cannula or mask; noninvasive or invasive positive pressure ventilation; or extracorporeal membrane oxygenation (ECMO) . Considering the potential of the COVID-19 pandemic to overwhelm healthcare systems, even in developed countries, there is a need to identify subgroups requiring different respiratory support techniques, as well as those requiring prolonged hospital admission, to inform service provision, allocate scarce medical resources appropriately and maximize treatment benefits. Previous studies have reported that older age and male sex were risk factors for poor prognosis in COVID-19 patients, with limited information about the need for respiratory support 4, 5 . A recent study found high levels of respiratory complications in COVID-19 patients requiring surgery, with an associated high mortality 6 .

We retrospectively reviewed demographic and clinical data available from electronic medical records at a branch of Tongji Hospital (Wuhan, China), a 1,050 bed hospital designated for severe and critically ill COVID-19 patients. This was approved and April 20, 2020 were consecutively included. Median age was 62 yr (interquartile range, 51-70; range, 0-95 yr) and 48.4% were female (Table 1) . Of the 1,792 patients, 72 (4.0%) were admitted from the emergency department and 1,720 (96.0%) were transferred from other hospitals. On admission, most cases were classified as severe (79.9%; i.e. respiratory rate ≥ 30 min -1 , blood oxygen saturation at rest ≤ 93%, PaO 2 /FiO 2 ≤ 300 mm Hg, or increased lung infiltration >50% within 48 h) or critical (14.0%; i.e. shock, respiratory failure or other organ or failure). Only 109 (6.1%) of cases were moderate (i.e. having symptoms and radiological findings of pneumonia, with no requirement for respiratory support). The percentage of patients who were categorised as critical on admission was higher in males and older patients.

Among all patients, high-flow nasal cannula oxygen therapy, noninvasive positive pressure ventilation and invasive positive pressure ventilation were given to 60 (3.3%), 135 (7.5%), 104 (5.8%) patients, respectively, with increased requirement for this amongst male and older patients. Extracorporeal membrane oxygenation was given to 10 (0.6%) patients and 8 (80.0%) of them were male.

The overall case-fatality rate (CFR) was 12.7% (228 deaths among 1,792 confirmed cases) and the median length of hospital stay among deceased patients was 11 (interquartile range, 6-20) days. CFR was elevated among male and older patients.

Among surviving patients, 22 (1.2%) were transferred to other hospitals to treat comorbidities after recovery from pneumonia and 1,542 (86.0%) were discharged to isolation centres for 14 days of quarantine. The length of stay among patients discharged was age dependent increasing from 22 (interquartile range, 14-31.3) days in those < 40 yr old to 34 (interquartile range, 24-43.8) days in those aged 80 or over. Of the 1,542 patients who were discharged, 514 (33.3%) required low-flow oxygen therapy at discharge, and the requirement increased with age.

A strength of the current study is the size of the cohort of COVID-19 patients requiring respiratory support. These data, from a single centre in Wuhan, provide insights into sex-specific and age-related factors. Our findings could be a useful supplement to previous studies of morbidity and mortality from COVID-19 3, 8, 9 , to help inform allocation of scarce healthcare resources (especially respiratory support) and mitigation of adverse effects of the COVID-19 pandemic in other countries. A third of patients with COVID-19 had abnormal pulmonary function at time of hospital discharge with a higher percentage in older patients. Our results are consistent with the findings of a previous study in which 84.2% of severe cases with COVID-19 were discharged with impairment of diffusion capacity 10 . Future studies to address persistent impairment of pulmonary function after COVID-19 and the impact of age are warranted.

A limitation with our study is that adherence to the national COVID-19 guidelines might have varied between patients, and therefore we are unable to assess the standard of management applied. While our impression is that adherence was rigorous, we plan to assess this as part of the future research with this cohort. Another limitation is that extraction of other relevant patient level data was restricted, such that more extensive analyses were not possible within the timescale and resources available. This highlights the challenges in rapidly developing a high-quality evidence base in the midst of a global pandemic. Limitations of existing healthcare data systems (e.g. paper medical records, no facility to efficiently extract data from individual records, etc.), lack of appropriately trained personnel as staff are diverted to dealing with acute crisis, and the impact of lockdown on collaborative working are all barriers that need to be considered.

Despite these issues, we believe that it is important to report these data as an 

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English version translated by the Chinese Society of Cardiology

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Data are presented as median (interquartile range) or n (%)

Low-flow nasal cannula oxygen therapy

Low-flow mask oxygen therapy

high-flow nasal cannula oxygen therapy; NIPPV, noninvasive positive pressure ventilation; IPPV, invasive positive pressure ventilation

ECMO, extracorporeal membrane oxygenation. a Only the highest level of respiratory support during hospitalisation is presented