Features including age, creatinine, white blood cell (WBC) count, lymphocyte /neutrophil count, blood urea nitrogen (BUN), aspartate aminotransferase (ASP), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), activated partial thromboplastin time (PTT), coughing, hypertension, cardiovascular disease (CVD), diabetes, dyspnea, oxygen therapy, pneumonia, gastrointestinal (GI) complications, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were identified as the most significant factors for predicting hospital LOS. This evidence concerns the gene CRP and pneumonia.