Breath Test Could Help Assess Liver Function

DDW: Breath Test Could Help Assess Liver Function
By Todd Neale, Staff Writer, MedPage Today
Published: June 05, 2009
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine and
Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner Earn CME/CE credit
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CHICAGO, June 5 -- A simple, quick breath test may help predict prognosis in patients with chronic liver disease, a researcher said here.


■Note that this study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Patients divided into low, medium, and high-risk groups according to the breath test had two-year survival rates of 98.9%, 89.7%, and 73%, respectively, Gadi Lalazar, M.D., of Hebrew University-Hadassah Medical Center in Jerusalem, reported at Digestive Disease Week.


The test might be able to add predictive value to the Model for End-Stage Liver Disease (MELD), he said.


Among patients with relatively high MELD scores of 17 and 18, a one-point increase in the breath test score was associated with a 30% higher risk of death.


The new test could be used to assess prognosis from the earliest stages of liver disease to cirrhosis, to help doctors determine whether a cirrhotic patient has enough liver function to undergo a surgical procedure, to prioritize patients for liver transplantation, and perhaps to decide when patients need to start therapy for chronic viral hepatitis, Dr. Lalazar said.


Brent Tetri, M.D., of Saint Louis University, a moderator at the press briefing where the findings were presented, said, "The liver does so many hundreds of different things, it would be very nice to have a good, simple test where we can just assign a number to how a liver's functioning."


Although MELD is able to predict prognosis in chronic liver disease, it is based on several blood tests and only estimates three-month risk.


In addition, patients with similar MELD scores will sometimes have different disease courses -- some will decompensate and die and others will not, according to Dr. Lalazar.


And often, the MELD score will only rise after a complication has occurred, at which point it's too late to prepare the patient for transplantation, he said.


So Dr. Lalazar and his colleagues assessed the predictive ability of the 13C-methacetin breath test.


Here's how it works: The patient drinks a solution containing methacetin, which is exclusively metabolized by the liver. He then sits and breathes normally. A nasal cannula measures exhaled carbon dioxide tagged with 13C for 15 minutes.


The changes in the amount of 13C exhaled allow the researchers to assess liver function.


The researchers gave the test to 575 patients with chronic liver disease of different etiologies. About two-thirds were the result of hepatitis C. More than a third (36.3%) were cirrhotic.


After two years, 25 patients had died from both liver-related and non-liver-related causes.


A survival model was constructed containing age, percent dose of methacetin recovered at 15 minutes (PDR15), and cumulative PDR15.


The model significantly predicted survival (P<0.0001) such that those with high scores had a two-year survival rate of 98.9%. Those with medium scores had a survival rate of 90%, and those with low scores had a survival rate of 73%.


In cirrhotic patients the test was also discriminatory with survival rates of 97%, 85% and 70% at 24 months respectively (P=0.0171).


Dr. Lalazar and colleagues found that the addition of the scores from the breath test helped predict mortality risk even within MELD categories.


Further research is needed, however, before determining whether patients flagged for increased risk by breath test should be get priority in treatment.


That the variability between breath tests in a single patient was about 11%, a consistency rate which Dr. Tetri called "pretty good."


There were no tolerability issues, according to Dr. Lalazar.



The study was supported in part by Exalenz Bioscience, which developed the breath test. One of the study authors is the medical director for the company.
Dr. Lalazar reported no conflicts of interest.

Dr. Tetri reported serving on advisory committees or review panels for Amylin Pharmaceuticals, Gilead Sciences, and Vertex Pharmaceuticals.



Primary source: Digestive Disease Week
Source reference:
Lalazar G, et al "The point of care 13C methacetin breath test accurately predicts long-term prognosis in patients with chronic liver disease: a noninvasive liver function test" DDW 2009; Abstract S1837.