Predicting dry weight in patients with cirrhotic ascites undergoing large-volume paracentesis

Ascites impairs the correct diagnosis and nutritional management in patients with cirrhosis, because the body weight, which is needed for nutritional assessment and calculation of nutritional needs, is overestimated. To adjust the weight in patients with ascites, dietetic guidances indicate substracting 2.2-14 kg or 5-15% of the measured body weight according to the degree of ascites, however, there is a lack of evidence to substantiate these values. The aim of this study was to develop new prediction equations to estimate the dry weight, comparing them with the currently used weight adjustments in patients with refractory cirrhotic ascites.

Cross-sectional study, that included patients with decompensated cirrhosis undergoing large-volume paracentesis. Patients were submitted to nutritional risk screening, nutritional assessment, and anthropometric measurements that included body weight, abdominal circumference (both measured before and after paracentesis) height, and upper mid-arm circumference. The volume of ascitic fluid drained was also registered. For the predictions of dry weight, linear regression models were performed using as predictor variables: height, pre-paracentesis weight, pre-paracentesis abdominal circumference, or mid-upper arm circumference, and as response variable: post-paracentesis weight. The capacity of these models to predict the post-paracentesis weight was evaluated by comparing it with the currently used predictions through the intraclass correlation coefficient (ICC) and the mean squared error (MSE).

Nineteen patients were included, 15 male, and 18 with high nutritional risk and malnutrition. The difference between post-paracentesis weight and pre-paracentesis weight was -5.0 (-3.6 to -9.9) kg, similar to ascitic fluid volume drained. Two equations were developed to predict post-paracentesis weight. ICC values showed that both prediction equations were strongly correlated (r > 0.94) with post-paracentesis weight. Our models also showed lower MSEs (<17.97), compared with the current predictions (MSEs <64.19, when the pre-paracentesis weight is adjusted from absolute values and MSEs <33.24 when adjusted from percentage values), indicating a more accurate prediction.

The predictive equations from this study may be better options for dry weight estimation in patients with refractory cirrhotic ascites since they showed higher reliability compared to the currently used weight adjustment. External validation in a larger sample is still needed to confirm the clinical applicability of these equations.