Child Pugh classification

Child-Pugh scoring system also known as the Child‐Turcotte‐Pugh score, is a major prognostic scoring systems in patients with chronic liver disease and liver cirrhosis ¹. However, the Model for End-Stage Liver Disease (MELD) score is now used for allocation in liver transplantation waiting lists, replacing Child‐Turcotte‐Pugh score ². Liver transplantation is now a standard of care therapy for well selected patients with end-stage liver disease, acute liver failure, acute on chronic liver failure and hepatocellular carcinoma (HCC) ³.

In 1964, Child and Turcotte ⁴ published a classification to assess the operative risk in cirrhotic patients who recovered from variceal bleeding, undergoing portosystemic shunt surgery. Child-Turcotte score included two continuous variables (bilirubin and albumin) and three discrete variables (ascites, encephalopathy, and nutritional status) which were empirically selected because they were felt to have their own influence on the prognosis in this context ⁵. Child-Turcotte score classifies patients in class A, B or C in relation to best (A), moderate (B), or worse (C) prognosis.

In 1973, Pugh et al. ⁶ used a modified version of Child-Turcotte classification for patients undergoing surgical transection for esophageal varices. They replaced nutritional status with prothrombin time and assigned a score ranging from 1 to 3 to each variable. Subsequently, this classification was used to predict the outcome of surgery in cirrhotic patients in general, and more recently, to stratify patients on the waiting list for liver transplantation. Similar to the original Child and Turcotte’s grading, neither the division of the grades nor the scoring system was validated statistically. However, a limitation comes from the fact that prothrombin time can also be expressed as either a percentage of normal (prothrombin index) or as international normalized ratio (INR), this latter being now the reference in many countries. The original cut-off values of 4 and 6 seconds for prothrombin time prolongation correspond approximately to a prothrombin index of 50% and 40%, respectively ⁷. These same values roughly correspond to an INR of 1.7 and 2, respectively. Child-Pugh score corresponds to the total of points for each item. According to the sum of these points, patients can be categorized into Child-Pugh grades A (5 to 6 points), B (7 to 9 points), or C (10 to 15 points). The variables included in Child-Pugh score are not specific markers of the synthesis (albumin and prothrombin) and elimination (bilirubin) functions of the liver. Indeed, changes in serum albumin may be also related to increased vascular permeability ⁸, especially in cases of sepsis, and large-volume ascites ⁹. Similarly, bilirubin can be increased as a consequence of impaired renal function, hemolysis, or sepsis ¹⁰. Prolonged prothrombin time can be a consequence of an intravascular activation of coagulation during sepsis ¹¹. Overall, the individual components of the Child-Pugh score encompass a broader spectrum of conditions than the single impairment of “liver function.” Child-Pugh score as a whole is also a marker of the multiorgan changes resulting from cirrhosis.

Table 1. Child Pugh classification

Parameter	Points
	1	2	3
Albumin (g/dL)	>3.5	3.5–2.8	<2.8
Bilirubin (mg/dL)	<2	2–3	>3
Ascites	Absent	Slight	Moderate
Encephalopathy	None	Glasgow Coma Scale 1–2	Glasgow Coma Scale 3–4
Prothrombin time (PT) (INR)	<1.7	1.8–2.3	>2.3
Child-Pugh score	A	B	C
Points	5–6	7–9	10–15

Child-Pugh score interpretation

Child-Turcotte-Pugh score is widely used to prognosticate patients with cirrhosis (see Tables 1 and 2). Although empirically derived, the Child-Turcotte-Pugh score has been shown to accurately predict outcomes in patients with cirrhosis and portal hypertension ¹². The Child-Turcotte-Pugh score scoring system incorporates five parameters: serum bilirubin, serum albumin, prothrombin time, ascites, and grade of encephalopathy ¹³. Based on the sum of the points from these five parameters, the patients are categorized into one of three Child-Turcotte-Pugh score classes: A, B, or C. Studies involving cirrhotic patients have shown that a patients’ Child-Turcotte-Pugh score score can estimate risk of death at 3-months and 1-year and 2-year survival. The two year survival of cirrhotic patients in Child-Turcotte-Pugh score class A, B, and C are 90%, 70% and 35% respectively ¹³. American Association for the Study of Liver Diseases recommends referral for liver transplantation evaluation in patients with cirrhosis and a Child-Turcotte-Pugh score of more than 7 ¹⁴.

Over many years, the routine use of these classifications have revealed some problems. First, both the degree of ascites and encepahlopathy are subjective assessments evaluated by physical examination alone ¹⁵. The widespread use of ultrasonography has led to more sensitive detection of ascites, but it is unclear how ascites diagnosed by ultrasonography alone is being categorized by various authors. Hepatic encephalopathy is often assessed by psychometric testing or slowing of frequency on an electroencephalography (EEG). It is not clear how these abnormalities are fitted into Child‐Turcotte‐Pugh classification ¹⁵. Secondly, both ascites and hepatic encephalopathy can be influenced by therapy such as diuretics, albumin infusion and lactulose and it is not clear if ascites and hepatic encephalopathy are scored at their best, or worst, or independent of specific therapy.

Several studies have shown that Child-Pugh score is an independent prognostic marker in the settings of ascites ¹⁶, ruptured esophageal varices ¹⁷, alcoholic cirrhosis ¹⁸, hepatitis C virus- (HCV-) related cirrhosis ¹⁹, primary biliary cirrhosis (PBC) ²⁰, primary sclerosing cholangitis ²¹, and Budd-Chiari syndrome ²². Child-Pugh score, which can be easily calculated at the bedside, has been widely used for selecting candidates for resection of hepatocellular carcinoma ²³ and nonhepatic surgery ²⁴.

Attempts have been made to improve the accuracy of Child-Pugh score by incorporating other markers of liver function (such as the clearance of galactose, indocyanine green, aminopyrine, and lidocaine) ²⁵. However, these additional markers had a limited value. The incorporation of conventional markers of nutritional status to Child-Pugh score also had a limited value ²⁶.

Since the five variables of Child-Pugh score were selected empirically, it can be anticipated that not all are independent predictors of prognosis. For example, albumin and prothrombin time are somewhat redundant. Including both variables in a single score may result in overweighting their own influence.

The cut-off value for each variable has been empirically selected. There is no evidence that moving from one class to the next one translates into a proportional change in mortality risk. As an example, patients with serum bilirubin above 100 μmol/L may be under-scored with Child-Pugh, because the limit for the upper class of bilirubin is only 51 mmol/L. This ceiling effect of discrete classes does not exist with continuous variables. In addition, the limits for qualitative variables (ascites and encephalopathy) are still vague. They may be influenced by subjective interpretation.

The five variables of Child-Pugh score are empirically given the same weight, which is also questionable. Multivariate analysis has shown that the proper weight of predictive factors is quite variable. For example, the weight of INR is three times as high as that of bilirubin in the Model for End-Stage Liver Disease (MELD) score ²⁷.

Child-Pugh score does not take into account specific variables, serum creatinine in particular, which have been shown to have a determinant impact on the prognosis of cirrhosis ¹⁶. Similarly, it has been shown that the addition of markers of portal hypertension, such as esophageal varices, portal blood velocity, and hepatic venous pressure gradient, would improve the accuracy of Child-Pugh score ²⁸.

Finally, Child-Pugh score does not take into account the cause of cirrhosis and the possibility of stopping (or slowing) the damaging process to the liver. This limitation is especially relevant in patients with alcoholic cirrhosis or with hepatitis B virus- (HBV-) related cirrhosis with viral replication.

Table 2. Child-Turcotte-Pugh score

[Source ²⁹ ]

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