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Table 2 Expert judgements made on mortality rates by care category in the excess mortality sub-model

From: Construction of a demand and capacity model for intensive care and hospital ward beds, and mortality from COVID-19

  Assumption within capacity Assumption with noICUbeds Assumption with noICUor ward beds
General ward care (1%) Very low mortality as these patients are un-escalatedand so will only occur with non-respiratory failure deaths or sudden deaths (1%) Very low mortality as these patients are un-escalated andso will only occur with non-respiratory failuredeaths or sudden deaths (3%) The risk remains low but will be greater than the mortality rate ward-based care
Ward care O2 > 35% (1%) This is a group of people who would be escalated to ICUif they deteriorated, so will only include sudden deaths (1%) Those who deteriorate may get CPAP on the ward, so the CPAP mortality rate from NIV/CPAP on ICU has been used (50%) Assume substantial mortality as use ofO2 > 35% indicates severe disease and risk to life. Assume that there will be no O2 outside of hospital. Set at 50% after discussion with ICU consultant
Ward care O2 > 35% (Ceiling) (40%) Assumption that this cohort will be frail with a CFS of 6–9. Mortality is about 40% at 28 days [11] (40%)Assumption that this cohort will be frailwith a CFS of 6–9. Mortality is about 40% at 28 days [11]. Assume unaffected by ICU absence (95%) This is a group of frail people who will have no medical support despite needing unusually high O2 flows to remain stable. Assume there will be no Ooutside of hospital
Supportive/HFO on ICU (1%) Assume the same as for NIV/CPAP on ICU (2%) Assume the same as for NIV/ CPAP on ICU (75%) With an assumption that no O2 available outside hospital, mortality in this group is likely to be high without it. Identified at having a risk to life by their need for admission toICU
NIV/CPAP on ICU (1%) There were 31 patients who received NIV only on ICU, none of whom died suggesting the mortality rate is below 3–4%. Deaths are only likely to occur if from non-respiratory causes such as sepsis or non-respiratory organ failure, otherwise they would have been escalated to IMV/ECMO [10] (2%) Assume that CPAP therapy cancontinue on the ward, but mortality rate is double the 'within capacity' mortality rate because ofreduction in supportive care (95%) Assume the vast majority would die without CPAP, otherwise they would have remained on high flow oxygen. Also assume that there will be no O2 outside hospital
NIV/CPAP on ICU(Ceiling) (83%) 20 out of 24 patients who received NIV died. These patients were frail with a mean CFS of 6 and would not have been considered for escalation of care [10] (90%) Assume that CPAP therapy cancontinue onthe ward, but mortality rate increasesdue to a reduction in supportive care (100%) Assumption that in the absence of any hospital bed, there would be no NIV and no chance of survival
IMV ± ECMO on ICU (40%) Since 1st September2020 mortality rate in those ventilated within 24hrs after admission is 40%. Assumption that the mortality rate is similar for those mechanically ventilated after24hrs [12] (100%) It is a reasonably safe assumption that the mortality rate would be close to 100% as IMV/ECMO are dangerous but potentially lifesaving procedures; only carried out if considered life-saving in this circumstance (100%) It is a reasonably safe assumption that the mortality rate would be close to 100% as IMV/ECMO are dangerous but potentially life-saving procedures; only carried out if consideredlife-saving in this circumstance
  1. ICU—intensive care unit, HFO—high flow oxygen, NIV—non-invasive ventilation, CPAP—continuous positive airways pressure, IMV—invasive mechanical ventilation, ECMO—extracorporeal membrane oxygenation, CFS—clinical frailty score, Ceiling—this refers to the most intensive level of care that is appropriate to each patient depending on their level of frailty and usually determined by the Clinical Frailty Score (CFS).