NPPB and atrial fibrillation: Age; systolic pressure on admission; presence of CKD; and presence of AF, BNP, NT-proBNP, eGFR C-G, total serum protein, albumin, bilirubin, ALT, total cholesterol, triglycerides, LDL, ferritin, TIBC, transferrin saturation, and serum iron were significantly different between the frail and non-frail patients, and they were chosen for model development.