Fourthly, despite the very high quality of the MIMIC-IV database, there were still some underlying variables and missing data that prevented the availability of certain clinical variables and surgical operation data, including left ventricular ejection fraction, functional classification of heart failure, echocardiographic data, variables such as C-reactive protein, lactate and D-dimer, implying that the inability to accurately identified the severity of RHD is another limitation of this study. This evidence concerns the gene CRP and rheumatic heart disease.