Based on early data published from China in 44, 672 patients [Wu Z et al. 2020]:
- 2.3% case fatality in all patients
- 14.8% case fatality in patients 80 years or older
- 14% of all patients had severe disease (hypoxemic, tachypneic)
- 5% were critical (respiratory failure, septic shock)
Case fatality rate is a number in which it is very difficult to have significant confidence. Some of the reasons are discussed in this summary article. [Battegay M, et al. 2020]
Ontario provincial experience suggests that of patients who are candidates for critical care and who wish to receive it, about 25% of patients convert to critical care if they require hospitalization for hypoxia.
Some physicians & teams find this estimate helpful: ISARIC 4C Consortium Mortality Risk and Deterioration Index.
Admissions to the ICU
- Patients are usually admitted to ICU due to respiratory failure, many of whom will progress to acute respiratory distress syndrome (ARDS).
- A small subset of those patients will develop shock and multi-organ dysfunction syndrome.
- A smaller proportion of patients will also develop cardiomyopathy with severe impairment of cardiac function.
What is ARDS?
ARDS is a syndrome of diffuse lung inflammation causing hypoxia refractory to ward level support.
Generally accepted criteria
- Acute onset, meaning onset over 1 week or less, AND
- bilateral opacities consistent with pulmonary edema must be present and may be detected on CT or chest radiograph, AND
- PaO2/FiO2 ratio < 300 mmHg with a minimum of 5 cm H20 PEEP (or CPAP), AND
- must not be fully explained by cardiac failure or fluid overload, in the physician’s best estimation using available information.
The average time from the onset of initial symptoms to ARDS in COVID is about 8 days.
Prognosis in Critically Ill
Some patients are at significantly increased risk of respiratory failure and death. [Yang et al., 2020] This seems to be consistent across a number of studies:
- cardiovascular disease
- chronic lung disease
- chronic kidney disease
Intensive Care National Audit and Research Centre (ICNARC) – January 29, 2021
- Critically ill UK patients with COVID-19 with critical care outcome reported
- All patients admitted to critical care:
- Prior to August 31, 2020 mortality was 39.4%
- Since Aug 31, 2020 mortality in patients with known outcome was 38.7%
- Patients receiving invasive ventilatory support:
- Prior to Aug 31, 2020 mortality was 47.7% (3754/7873)
- Since Aug 31, 2020 mortality in patients with known outcome was 62.7% (4002/6387)
- Mechanically ventilated patients admitted between September 1 – November 30, 2020:
- Age > 70: 76% died in critical care unit
- Age 50-69: 59.3% died in critical care unit
- Age 16-49: 36.8% died in critical care unit
- Any renal support: 78% died in critical care unit
Lim ZJ, Subramaniam A, Reddy MP, et al. Case fatality rates for patients with COVID-19 requiring invasive mechanical ventilation (IMV). A Meta-analysis. Am J Resp Crit Care Med 2020;203(1):54-66.
What did we learn
“Of 57,420 adult patients in 69 studies who met the inclusion criteria for this systematic review and meta-analysis of patients with severe COVID-19, the overall estimate for the reported CFR was 45% (95% confidence interval, 38–52%). Definitive hospital outcomes were only available for 13,120 (36.6%) patients. Significant variability in CFR was also present by age of patients and geographic location of the study.“
When information on prognosis is important for an individual patient to make decisions or the decision is challenging, we recommend seeking multidisciplinary input from the physician that knows the patient best and specialists in infectious diseases and critical care.