The contribution of ascitic fluid to body weight in patients with liver cirrhosis, and its estimation using girth: a cross-sectional observational study

Abstract

BACKGROUND: There is a high prevalence of malnutrition among people with decompensated liver disease. Standard nutritional screening tools use weight and body mass index (BMI) to identify risk, although these are difficult to measure for those with ascites, often secondary to liver cirrhosis. Dietetic guidance suggests adjusting for ascitic weight by 2.2-14 kg, although there is a lack of evidence to substantiate these values. The present study aimed to measure the contribution of ascitic fluid weight and compare this with the current guidance, as well as to examine whether girth circumference can be used to estimate ascitic weight. METHODS: A cross-sectional, observational study was conducted over 13 weeks. Participants attending for paracentesis were weighed, their girths measured, and BMI was calculated pre- and post-paracentesis. Fluid removed via paracentesis was recorded. Ethical approval was received (IRAS project ID: 218747). RESULTS: Eighteen participants underwent paracentesis. The range of ascitic fluid drained was 3.8-19 L [mean (SD) = 8.7 (3.7) L]. Weight difference between pre- and post-paracentesis was in the range 4.5-20 kg [mean (SD) = 8.7 (3.9) kg]. Ascitic fluid weight is shown to be higher in each category (minimal, moderate, severe ascites) than the current guidance values. Weight difference was greater than 14 kg in 11% (n = 2) of participants. A strong, statistically significant relationship (rho = 0.68, P ≤ 0.01) between ascitic weight and pre-paracentesis girth was found. An equation was formulated to enable the estimation of ascitic fluid from pre-paracentesis girth. CONCLUSIONS: Current dietetic guidance should be re-evaluated to reflect the greater weight differences identified. Measuring girth pre-paracentesis may help to inform dry weight estimation. Further research is required to verify the accuracy of estimating ascitic weight from pre-paracentesis girth.