The evaluation of liver function reserve and prognosis of patients with cirrhosis is a topic of great concern to clinicians. Since liver function is multifaceted and the factors affecting the prognosis of patients with cirrhosis are complex, various single indicators have certain clinical value in determining the prognosis of patients with cirrhosis, but at the same time, there are certain limitations. Therefore, for a long time, people have focused on the use of multiple indicators to make a comprehensive judgment, that is, to classify some major indicators that can reflect the degree of liver function damage into different levels, in order to determine the prognosis of patients with cirrhosis. A good model should have fewer indicators, be easily accessible, objective, and easily generalizable. Guided by the evidence-based approach, liver function has been graded, scored or quantified through empirical, retrospective or prospective studies. Two of the most widely used methods for assessing liver function in the world are described below. 1.(Child-Turcotte-Pugh) CTP grading (1) Evolution of CTP grading In 1961 Child and his colleagues summarized the morbidity and mortality rates after portal vein anastomosis in 131 patients with cirrhotic portal hypertension or other patients with portal hypertension, and classified patients with cirrhosis as mild, moderate, or severe according to the severity of their disease. 1964 Child and Turcotte published the Child-Turcotte classification as a chapter in their monograph “Surgery and Portal Hypertension”, which used five indicators (albumin, ascites, hepatic encephalopathy, bilirubin, nutritional status) that are still commonly used today. Patients with cirrhosis were divided into groups A, B, and C. Group A had no jaundice, ascites, and hepatic encephalopathy, normal albumin levels, and good nutritional status, and could function normally; group C had advanced liver disease: jaundice, ascites, hepatic encephalopathy, and even coma, poor nutritional status, and low albumin levels; group B was between groups A and C. They also conducted a retrospective study of the morbidity and mortality rates in 128 patients who underwent elective portal vein shunts, in which the morbidity and mortality rates were 0%, 9% and 53% in groups A, B and C, respectively, i.e. confirming that this grading can better evaluate the reserve of liver function. Although the selection and grading of the above-mentioned indexes have not been experimentally proven and statistically confirmed, the Child-Turcotte grading has been widely used after more than 40 years of clinical practice. However, people gradually realized that this grading method is too general and there are certain difficulties in grading some indicators: for example, ascites, hepatic encephalopathy and nutritional status are subjective indicators, which are easily influenced by clinicians’ subjective perceptions; albumin and jaundice change with treatment, so it is difficult to have accurate judgments; sometimes it is not possible to group patients’ indicators into exactly one group, and sometimes it is not possible to distinguish different patients’ severity within a group. The severity of the disease. In 1973, Pugh modified the Child-Turcotte classification (CTP classification) to address the shortcomings of Child-Turcotte. He replaced the most subjective index of nutritional status with Prothrombin Time (PT), and scored the five indexes 1, 2, and 3 respectively according to the severity of the disease, and the five scores of each patient were added up to the total score, with 5-6 being grade A, 7-9 being grade B, and 10-15 being grade C. Since then, CTP grading has been widely used in descriptive studies or clinical treatment of patients with cirrhosis. (2) Advantages of CTP grading and its clinical significance CTP grading is more accurate than Child-Turcotte grading in delineating the condition of cirrhotic patients and can evaluate the liver reserve function in end-stage liver disease. Although the selection and grading of these indicators have not been statistically proven, the CTP grade has been accepted and widely used in patients with cirrhosis for 40 years, and it should be said that the use of the CTP grade is of epoch-making significance for the evaluation of liver reserve function in patients with end-stage liver disease. In 1997, the United Network for Organ Sharing (UNOS) established the criteria for liver transplantation based on CTP grading, which was divided into grade 1, grade 2A (CTP score ≥10 with complications), grade 2B (CTP score ≥10 or CTP score ≥7 with complications), and grade 3 (CTP score of 7-10). Although not all indicators were statistically independent predictors of survival, when combined, it had a sensitivity of 78% and a specificity of 83% in predicting mortality, and they concluded that CTP grading was clinically valuable in predicting 1-year survival in patients with cirrhosis. (3) Shortcomings of CTP grading Although CTP grading is more accurate than Child-Turcotte grading, there are also shortcomings: (1) subjective indicators such as ascites and hepatic encephalopathy are used in CTP grading, which makes the grading vary greatly depending on the judge; (2) CTP grading is still imprecise, for patients within the same grading, the disease may vary greatly, and CTP grading can no longer distinguish the severity of the disease; (3) CTP grading is still imprecise. CTP grading cannot distinguish the severity of the disease; ③ the albumin used in CTP grading is easily affected by artificial factors, such as the infusion of albumin can increase the concentration of serum albumin in a short period of time; prothrombin time varies greatly from country to country and even from laboratory to laboratory in the same region, which can easily lead to inconsistent grading; ④ CTP grading is narrow, which limits liver disease to the range of 5 to 15 points The CTP classification is narrow, which limits liver disease to 5-15 points, so that there are many patients with the same score in the same classification, which makes it difficult to judge the disease and choose the clinical treatment plan, especially to select liver transplant patients from the candidate list. 2.(Model for End-Stage Liver Disease) MELD score (1) Generation of MELD score Malinchoc and Kamath of Mayo Clinic in the United States believed that CTP grading is useful in determining the transjugular intrahepatic portosystem (TIP). Intrahepatic Portosystemic Shunt (TIPS) has shortcomings in determining the survival of patients after the procedure. In order to find a more accurate method to determine the prognosis of these patients, they selected patients who underwent TIPS for the treatment of intractable ascites and prevention of bleeding, and used Cox proportional risk regression statistics to identify four laboratory and clinical indicators that better predicted survival at 3 months in these patients: international normalized ratio of serum creatinine, bilirubin, prothrombin time (PT) ( International Normalized Ratio (INR) and etiology, and the regression coefficients of these four indicators were used to form the risk of death prediction formula: R=0.957×ln(creatinine mg/dl)+0.378×ln(bilirubin mg/dl)+1.120×ln(INR)+0.643×etiology (cholestatic and alcoholic) Malinchoc et al. showed that the Mayo TIPS model was superior to the CTP classification in determining the survival of patients after TIPS when compared with the CTP classification. In 2001, Kamath et al.[7] examined the validity of this model for general use in the determination of chronic advanced liver disease, particularly as a criterion for liver transplantation, using data from four separate groups of patients: inpatients with cirrhotic decompensation, outpatients with non-cholestatic cirrhosis, and patients with primary biliary cirrhosis. Primary Biliary Cirrhosis (PBC) patients and patients with non-elective cirrhosis in the 1980s for validation. Kamath first called this formula “Model for End-stage Liver Disease “(2) Advantages of MELD score and clinical application Because of the subjectivity and arbitrariness of CTP grading, and as a criterion for liver transplantation donor allocation, the waiting time is actually a key factor, and MELD score has many advantages that CTP grading does not have. In February 2002, UNOS formally adopted the MELD score as the standard for adult liver transplantation, i.e., grade 1 is still retained, and grades 2A, 2B and 3 are based on the MELD score, with the higher MELD score taking precedence and the waiting time prevailing for the same MELD score. (3) the limitations of the MELD score Although the MELD classification to avoid many of the shortcomings of the CTP classification, but the MELD classification itself also has some problems, its creator Kamath et al. also admitted that the MELD classification has many limitations, the need for continuous improvement and refinement, in its universal application before, need to be validated in different countries and regions. the MELD classification of the main existing The serum creatinine used in MELD classification is affected by liver disease itself, but also by the patient’s nutritional status, blood volume status, diuretics, non-steroidal drugs, the presence of primary renal lesions, etc. In addition, infection, inability to eat, vitamin K deficiency, etc., can also affect PT, bilirubin and other indicators, these conditions outside the liver disease caused by the fluctuations in the indicators will directly affect the true liver disease. Kamath pointed out that, in order to avoid extra-hepatic factors caused by serum creatinine fluctuations affect the accuracy of MELD classification, in the use of MELD classification to determine the condition, should be used on the basis of the patient’s hemodynamic stability and adequate rehydration. If serum creatinine clearance is used instead of serum creatinine, it will make MELD grading more accurate to reflect the changes of liver function; although INR tries to avoid the regional variability of PT, if Prothrombin Activity (PTA) is used instead of INR, which has less variability, it may make MELD grading more uniform. Although statistical analysis showed that the complications of portal hypertension in cirrhosis, such as ascites, hemorrhage, and hepatic encephalopathy, had no significant effect on the function of MELD grading, whether the actual prognosis of patients is consistent with the theoretical statistical analysis still needs further clinical observation and verification. Because any experienced hepatologists believe that the above complications are a direct threat to the life of the patient. Angermayr et al. performed MELD score and CTP classification in 501 patients with liver cirrhosis after elective TIPS and used Cox proportional risk regression model to predict the survival rate after surgery. They found that both the CTP score and the MELD score entered the equation and MELD was the main predictor, but the C-statistic value showed that the MELD score and the CTP score were equivalent and their predictive accuracy was similar for survival at 1 month, 3 months, and 1 year after surgery, and they concluded that there was no theoretical basis for using the MELD score to replace the CTP score, which had been tested in practice for more than 40 years. 3, Outlook Whether CTP classification, or MELD score, are the severity of liver disease is divided. With the improvement of scholars’ research and understanding of liver fibrosis, the development of diagnosis and treatment technology and equipment, and the emergence of new sensitive indicators, it is possible that CTP classification and MELD score can no longer meet the needs of our judgment of the disease, and we should have a more accurate and detailed assessment of liver function in order to adopt the most effective and appropriate treatment for patients with cirrhosis in a timely manner.