Four-organ SOFA score as a potential tool to triage use of continuous kidney replacement therapy in COVID-19 patients with acute kidney injury: a retrospective two-center study

Acute kidney injury requiring continuous kidney replacement therapy (AKI-CKRT) in the setting of coronavirus disease 2019 (COVID-19) carries a high mortality. In this two-center retrospective cohort study, we analyzed whether a simplified Sequential Organ Failure Assessment (SOFA) score, the 4-organ SOFA score with renal and neurologic sub-scores removed, would perform as well as the full SOFA score in predicting mortality. In our primary cohort, we identified 63 patients with COVID-19 hospitalized in April 2020 to July 2021 with AKI-CKRT and determined their 4-organ and full SOFA scores at CKRT initiation. Thirty-day and in-hospital mortality were 73.0% and 82.5%, respectively. The median 4-organ SOFA score at CKRT initiation among 30-day survivors was 7 (interquartile range 5.5-8.5) versus 8 (7-10) among 30-day non-survivors (<i>p</i> = 0.017). Four-organ SOFA scores for those who survived versus died before discharge were similar (<i>p</i> = 0.071). The full SOFA scores in survivors versus non-survivors were similar (<i>p</i> > 0.05). When comparing receiver operating characteristic curves, the 4-organ SOFA score to predict 30-day mortality performed best (area under curve 0.67). For external validation, we repeated our analysis in 88 patients with COVID-19 and AKI-CKRT from the MIMIC-IV database, and again the 4-organ score performed as well as the full SOFA score to predict 30-day and in-hospital mortality. Though hypothesis-generating and requiring additional validation, these findings suggest that 4-organ SOFA score performs as well as full SOFA score in predicting mortality in patients with COVID-19 and AKI-CKRT. However, these results reinforce prior data that SOFA score has limited prognostic value in COVID-19.