Table 2.

Frequency of severe COVID-19 and related mortality during the study period stratified by case definition and approach to missing data

Case Definition Used to Define Severe COVID-19 and Approach to Missing Data	Proportion of Symptomatic Patients with Severe COVID-19 (95% CI)*	Hospital Mortality in Patients with Severe COVID-19 (95% CI)*
Modified WHO case definition† with multiple imputation of missing respiratory rate and oxygen saturation values	29.1% (26.9–31.5%)	25.1% (20.6–30.2%)‡
Modified WHO case definition† assuming all missing respiratory rate values <30 breaths/min and oxygen saturation values >90%	28.4% (25.8–31.2%)	25.1% (20.6–30.3%)
Modified WHO case definition† excluding respiratory rate criterion and assuming all missing oxygen saturation values >90%	28.3% (25.6–31.0%)	25.3% (20.8–30.5%)
Receipt of oxygen therapy alone	26.0% (23.5–28.7%)	27.1% (22.3–32.6%)

Definition of abbreviations: CI = confidence interval; COVID-19 = coronavirus disease; WHO = World Health Organization.

Frequency defined as the proportion of all symptomatic COVID-19 admissions who fulfilled criteria for severe COVID-19.

^*Confidence intervals generated using Wilson scores.

^† One or more of the following criteria: oxygen saturation ⩽ 90%, respiratory rate ⩾ 30 breaths/min, signs of respiratory distress (chest indrawing, nasal flaring, grunting respirations), receipt of oxygen therapy.

^‡ Reflects first imputed dataset; results from other four imputed datasets as follows: 24.4 (20.0–29.4), 25.1 (20.6–30.2), 24.4 (20.0–29.5), 25.3 (20.8–30.4).