PPP6R3 and chronic kidney disease: In the model on COVID-19 and ARDS the interaction was significant for SAPS3 Box III (p < 0.001), age (p < 0.001) and chronic renal failure (p = 0.001), indicating a stronger association of SAPS3 Box III, age and chronic renal failure to 60-day mortality in COVID-19 than in ARDS (Fig. 3).