“…Two studies were prospective [ 34 , 36 ], while the remaining nine were retrospective [ 30 , 31 , 32 , 33 , 35 , 37 , 38 , 39 , 40 ]. Six studies were performed in Asia [ 30 , 33 , 35 , 38 , 39 , 40 ], three in Europe [ 32 , 36 , 37 ], and two in America [ 31 , 34 ]. End points included disease severity based on current clinical guidelines in six studies [ 30 , 33 , 34 , 35 , 39 , 40 ], survival in three [ 31 , 36 , 37 ], and transfer to ICU in two [ 32 , 38 ].…”