Receiver operating characteristics for Simplified Acute Physiology Score 3 (SAPS3) in total, and Box 1 and Box 3 of SAPS3, in the entire cohort.

Receiver operating characteristics for Simplified Acute Physiology Score 3 (SAPS3) in total, and Box 1 and Box 3 of SAPS3, in the entire cohort.</p

Calibration belt plot of Simplified Acute Physiology Score 3 (SAPS3) in total in the entire cohort.

Calibration belt plot of Simplified Acute Physiology Score 3 (SAPS3) in total in the entire cohort.</p

Receiver operating characteristic for the new prognostic models comprising prior illness and acute physiological derangement versus days in the ICU in the validation dataset.

Only includes complete cases with all information necessary to be included in both the prior and acute models. Prior illness: black circles, acute physiological derangement: grey triangles. AUC: area under the receiver operating characteristic. (PDF)</p

Cohort flowchart.

COVID-19 is associated with prolonged intensive care unit (ICU) stay and considerable mortality. The onset of persistent critical illness, defined as when prior illness predicts death better than acute physiological derangement, has not been studied in COVID-19. This national cohort study based on the Swedish Intensive Care Registry (SIR) included all patients admitted to a Swedish ICU due to COVID-19 from 6 March 2020 to 9 November 2021. Simplified Acute Physiology Score-3 (SAPS3) Box 1 was used as a measure of prior illness and Box 3 as a measure of acute derangement to evaluate the onset and importance of persistent critical illness in COVID-19. To compare predictive capacity, the area under receiver operating characteristic (AUC) of SAPS3 and its constituent Box 1 and 3 was calculated for 30-day mortality. In 7 969 patients, of which 1 878 (23.6%) died within 30 days of ICU admission, the complete SAPS3 score had acceptable discrimination: AUC 0.75 (95% CI 0.74 to 0.76) but showed under prediction in low-risk patients and over prediction in high-risk patients. SAPS3 Box 1 showed markedly better discrimination than Box 3 (AUC 0.74 vs 0.65, P</div

Receiver operating characteristic for the new prognostic models comprising prior illness and acute physiological derangement versus days in the ICU in the validation dataset.

Prior illness: black circles, acute physiological derangement: grey triangles. AUC: area under the receiver operating characteristic. (PDF)</p

Unadjusted odds ratios (OR) and 95% confidence intervals (CI) for all categorical predictors.

Unadjusted odds ratios (OR) and 95% confidence intervals (CI) for all categorical predictors.</p

Adjusted odds ratios (OR) and 95% confidence intervals (CI) for all categorical predictors.

Predictors adjusted for all other variables in the respective model: sex, chronic lung disease, impaired immune system, chronic liver disease, diabetes, obesity and cancer adjusted for each other and age. Vasoactive medication prior to ICU admission and mechanical ventilation before ICU adjusted for each other and highest body temperature, lowest systolic blood pressure, highest bilirubin, highest creatinine, highest leucocyte count, lowest thrombocyte count, lowest pH, lowest PaO2, number of symptomatic days prior to ICU admission and days in hospital prior to ICU admission. (PDF)</p

Unadjusted odds ratios (OR) and 95% confidence intervals (CI) for all continuous predictors.

Presented using restricted cubic splines with knots at the 10th, 50th and 90th percentile. (PDF)</p

Receiver operating characteristic for Box 1 and Box 3 of Simplified Acute Physiology Score 3 versus days in the ICU in the entire cohort.

Box 1 black circles, Box 3 grey triangles. AUC: area under the receiver operating characteristic.</p

Receiver operating characteristic for the new prognostic models comprising prior illness and acute physiological derangement versus days in the ICU in the validation dataset.

Missing data replaced with single imputation of a normal value. Prior illness: black circles, acute physiological derangement: grey triangles. AUC: area under the receiver operating characteristic. (PDF)</p