(131) Survival of critically ill COVID-19 patients in Sweden during the first two-and-a-half years of the pandemic

Background: It's important to note that studies on COVID-19 ICU patients have predominantly been conducted in selected healthcare facilities, relying on case reports or small cohorts, and with relatively short follow-up periods. The mortality trend and predictors among COVID-19 ICU patients across various variants are not well understood, and there is limited evidence on this critical aspect.

Objectives: To examine the survival trend among critically ill COVID-19 patients during the first two-and-a-half years of the pandemic and investigate potential predictors across different variants of concern periods.

Methods: A prospective cohort study conducted in adult COVID-19 patients admitted to Intensive Care Units (ICUs) in Sweden from Mar 6, 2020, to Dec 31, 2022 (N = 8975) followed them to the first of: outcome (COVID-19-related death), emigration date, death unrelated to COVID-19, or end of follow-up (31 Dec 2022). Data sourced from the Swedish Intensive Care Register, linked to national registers. Survival probability and predictors of COVID-19 death were estimated using Kaplan-Meier and Cox regression analyses.

Results: During the follow-up, a total of 2,927 patients (32.6%) died, comprising 2,080 men and 847 women, with a mean age of death [SD] of 70 [10.6] years. The survival rate among ICU patients appears to have changed over time, with a worse survival rate in the Omicron period. The adjusted hazard ratios (aHR) comparing older and younger ages were consistently strong but slightly attenuated in the Omicron period. After adjustment, the aHR for death was higher for men, older age (40+), low income, and with comorbid chronic heart disease, chronic lung disease, impaired immune disease, chronic renal disease, stroke, and cancer, and for those requiring invasive or non-invasive respiratory supports, developed septic shock, or suffered organ failures (p < 0.05). Foreign-born patients, those with booster vaccines, and steroid users had better survival (aHR=0.87, 95%CI 0.80-0.95; 0.74, 0.65-0.84; and 0.91, 0.84-0.98, respectively). The observed associations were similar across different variant periods.

Conclusions: In this nationwide Swedish cohort, ICU survival rates changed over two and a half years of the pandemic. Older age was a strong predictor across all periods. Most other mortality predictors remained consistent across different variant periods.