Phase-1 Evaluation of 13 C-Liver Function Breath Tests
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CORRESPONDENCE
Phase-1 Evaluation of
13
C-Liver Function Breath Tests
Anna Kasicka-Jonderko • Krzysztof Jonderko
Published online: 11 January 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com
Dear Sir, We read with great interest the paper by Afolabi et al. [1]. It is true that 13C-liver function breath tests (13CLFBTs) appear to be attractive both to patients and physicians because of their non-invasive protocol, as opposed to diagnostic procedures infringing the body integrity, which inherently entails a liver biopsy. Unfortunately, after almost three decades during which 13C-LFBTs were available to clinicians, those tests still have not paved their way to become a routine diagnostic tool. The breakthrough made by the quoted paper consists in the clear delineation of targets for future research which, if attained, should gain an objective view upon the clinical usefulness of those tests. Accordingly, phase one of this validation process should involve evaluation of reproducibility, the second one involves the assessment of prognostic utility, and ultimately the third phase should investigate the effect of 13 C-LFBTs upon the patients’ outcome [1]. One should be aware that the result of a breath test, like in the case of any other quantitative diagnostic method applied in medicine, may contain a certain degree of inexactitude because an immanent feature of any measurement is its proneness to random as well as systematic errors. Therefore it is necessary to identify possible sources of measurement errors and to estimate of their contribution to the overall error of a diagnostic method and, as the ultimate step, to undertake means to possibly minimize it. In the case of 13C breath tests, the total measurement error will be accounted for by the precision and exactitude
A. Kasicka-Jonderko K. Jonderko (&) Department of Basic Biomedical Science, School of Pharmacy, Medical University of Silesia, 3, Kasztanowa Street, 41-205 Sosnowiec, Poland e-mail: [email protected]
of the apparatus used to determine the content of 13CO2 within samples of the expired air, degree of conformity with the recommended protocol of accomplishing the test, and inherent biological variability of the living organism undergoing a diagnostic procedure. The error introduced by the measurement equipment is relatively easy to estimate, because it will be characterized by sensitivity, linearity range, as well as by within- and between-series consistency of measurement results. Those items are basically addressed by manufacturers, and a daily routine of calibration assures the maintenance of optimum performance of the equipment. Knowledge of the performance of the measuring system is of course necessary to adjust an optimum dosage of the 13C-labeled substrate applied for a given breath test [2]. Minimization of the error associated with the implementation of a breath test is achieved by standardization of the composition and method of preparing a test meal, the time allowed for its consumption, number
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