Table 3 Feature selection using several algorithms.

1

Whale Optimization (WO)²¹

15

Age, SpO2, Pulse, Respiratory rate, Hemoglobin, Haemtocrit, Neutrophil, NLR, Creatinine, Sodium, Potassium, ALT, Albumin, HbA1c and CRP

2

Sine Cosine Algorithm (SCA)²²

3

Gender, Basophil and Albumin

3

Salp Swarm Optimization (SSO)²³

18

SpO2, Pulse, Respiratory rate, Hematocrit, Neutrophil, NLR, Monocyte, Basophil, Urea, Sodium, Potassium, T. Bilirubin, AST, ALT, ALP, CRP, D-Dimer and Ferritin

4

Particle Swarm Optimization (PSO)²⁴

6

Neutrophil, Potassium, T. Bilirubin, AST, ALT and CRP

5

Jaya Algorithm (JA)²⁵

11

Age, SpO2, Hemoglobin, Hematocrit, Neutrophil, Lymphocyte, Basophil, ALT, ALP, HbA1c and CRP

6

Harris Hawks Optimization (HHO)²⁶

6

SpO2, Hemoglobin, TWBC, NLR, Basophil and CRP

7

Grey Wolf Optimizer (GWO)²⁷

10

Age, TWBC, Lymphocyte, Monocyte, Creatinine, Sodium, D. Bilirubin, AST, Protein and CRP

8

Genetic Algorithm (GA)²⁸

9

SpO2, Lymphocyte, NLR, Eosinophil, Potassium, AST, ALT, CRP and D-Dimer

9

Flower Pollination Algorithm (FPO)²⁹

15

Hemoglobin, Hematocrit, Neutrophil, Lymphocyte, NLR, Monocyte, Eosinophil, Basophil, Potassium, T. Bilirubin, AST, ALT, ALP, CRP and Ferritin

10

Firefly Algorithm (FA)³⁰

14

Age, SpO2, Pulse, Respiratory rate, Neutrophil, Lymphocyte, Eosinophil, Urea, Sodium, Potassium, AST, HbA1c, CRP and Ferritin

11

Differential Evolution (DE)³¹

10

Respiratory rate, Hemoglobin, TWBC, Neutrophil, NLR, Eosinophil, Creatinine, ALP, HbA1c and CRP

12

Cuckoo Search Algorithm (CSA)³²

10

Gender, TWBC, Neutrophil, NLR, Monocyte, Sodium, AST, ALT, ALP and CRP

13

Bat Algorithm (BA)³³

9

TWBC, Neutrophil, Lymphocyte, NLR, Basophil, AST, Protein, HbA1c and CRP

14

Mutual Information (MI)³⁴

15

Albumin, NLR, Protein, CRP, D-Dimer, SpO2, Lymphocyte, LDH, Basophil, Eosinophil, Urea, Neutrophil, Respiratory rate and HbA1c