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Performance of an Optimized Paper-Based Test for Rapid Visual Measurement of Alanine Aminotransferase (ALT) in Fingerstick and Venipuncture Samples

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      Abstract

      BackgroundA paper-based, multiplexed, microfluidic assay has been developed to visually measure alanine aminotransferase (ALT) in a fingerstick sample, generating rapid, semi-quantitative results. Prior studies indicated a need for improved accuracy; the device was subsequently optimized using an FDA-approved automated platform (Abaxis Piccolo Xpress) as a comparator. Here, we evaluated the performance of the optimized paper test for measurement of ALT in fingerstick blood and serum, as compared to Abaxis and Roche/Hitachi platforms. To evaluate feasibility of remote results interpretation, we also compared reading cell phone camera images of completed tests to reading the device in real time.Methods96 ambulatory patients with varied baseline ALT concentration underwent fingerstick testing using the paper device; cell phone images of completed devices were taken and texted to a blinded off-site reader. Venipuncture serum was obtained from 93/96 participants for routine clinical testing (Roche/Hitachi); subsequently, 88/93 serum samples were captured and applied to paper and Abaxis platforms. Paper test and reference standard results were compared by Bland-Altman analysis.FindingsFor serum, there was excellent agreement between paper test and Abaxis results, with negligible bias (+4.5 U/L). Abaxis results were systematically 8.6% lower than Roche/Hitachi results. ALT values in fingerstick samples tested on paper were systematically lower than values in paired serum tested on paper (bias -23.6 U/L) or Abaxis (bias -18.4 U/L); a correction factor was developed for the paper device to match fingerstick blood to serum. Visual reads of cell phone images closely matched reads made in real time (bias +5.5 U/L).ConclusionsThe paper ALT test is highly accurate for serum testing, matching the reference method against which it was optimized better than the reference methods matched each other. A systematic difference exists between ALT values in fingerstick and paired serum samples, and can be addressed by application of a correction factor to fingerstick values. Remote reading of this device is feasible.

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      Most cited references 26

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      Measuring agreement in method comparison studies.

      Agreement between two methods of clinical measurement can be quantified using the differences between observations made using the two methods on the same subjects. The 95% limits of agreement, estimated by mean difference +/- 1.96 standard deviation of the differences, provide an interval within which 95% of differences between measurements by the two methods are expected to lie. We describe how graphical methods can be used to investigate the assumptions of the method and we also give confidence intervals. We extend the basic approach to data where there is a relationship between difference and magnitude, both with a simple logarithmic transformation approach and a new, more general, regression approach. We discuss the importance of the repeatability of each method separately and compare an estimate of this to the limits of agreement. We extend the limits of agreement approach to data with repeated measurements, proposing new estimates for equal numbers of replicates by each method on each subject, for unequal numbers of replicates, and for replicated data collected in pairs, where the underlying value of the quantity being measured is changing. Finally, we describe a nonparametric approach to comparing methods.
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        Diagnostics for the developing world: microfluidic paper-based analytical devices.

        Microfluidic paper-based analytical devices (microPADs) are a new class of point-of-care diagnostic devices that are inexpensive, easy to use, and designed specifically for use in developing countries. (To listen to a podcast about this feature, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html.).
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          Patterned paper as a platform for inexpensive, low-volume, portable bioassays.

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            Author and article information

            Affiliations
            [1 ]Diagnostics For All, Cambridge, Massachusetts, United States of America
            [2 ]Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
            [3 ]The Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, Massachusetts, United States of America
            [4 ]Tufts Clinical and Translational Science Institute, Tufts University, Boston, Massachusetts, United States of America
            [5 ]Division of Hepatology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
            [6 ]Department of Laboratory Medicine, Boston Children’s Hospital, Boston, Massachusetts, United States of America
            Emory University/Georgia Insititute of Technology, UNITED STATES
            Author notes

            Competing Interests: The authors have read the journal’s policy and have the following conflicts to declare: Patent application filed pertaining to device: U.S. Provisional Patent Application No. 61/555,977 “Quantitative microfluidic devices” (Kumar S. and Jain S. are listed as inventors of this application). This does not alter their adherence to all the PLOS ONE policies on sharing data and materials. There are no other relevant declarations relating to employment, consultancy, patents, products in development or modified products, etc.

            Conceived and designed the experiments: SJ RR FN EC RS RB MC NA SK NRP. Performed the experiments: SJ RR EC RS SK NRP. Analyzed the data: SJ RR FN EC RS SK NRP. Contributed reagents/materials/analysis tools: SJ FN EC SK. Wrote the paper: SJ RR FN EC RS SK NRP. Assisted with patient recruitment: RB MC NA.

            Contributors
            Role: Academic Editor
            Journal
            PLoS One
            PLoS ONE
            plos
            plosone
            PLoS ONE
            Public Library of Science (San Francisco, CA USA )
            1932-6203
            28 May 2015
            2015
            : 10
            : 5
            26020244
            4447376
            10.1371/journal.pone.0128118
            PONE-D-15-04189
            (Academic Editor)

            This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

            Counts
            Figures: 4, Tables: 2, Pages: 15
            Product
            Funding
            This work was supported by a CIMIT (Center for Integration of Medicine and Innovative Technology) Young Investigator Award (to Nira Pollock). Diagnostics For All provided all kits for the study and participated in study execution, analysis, and write-up.
            Categories
            Research Article
            Custom metadata
            All relevant data are within the paper.

            Uncategorized

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