BACKGROUND. Clinical laboratory tests are now being prescribed and made directly available to consumers through retail outlets in the USA. Concerns with these test have been raised regarding the uncertainty of testing methods used in these venues and a lack of open, scientific validation of the technical accuracy and clinical equivalency of results obtained through these services.
METHODS. We conducted a cohort study of 60 healthy adults to compare the uncertainty and accuracy in 22 common clinical lab tests between one company offering blood tests obtained from finger prick (Theranos) and 2 major clinical testing services that require standard venipuncture draws (Quest and LabCorp). Samples were collected in Phoenix, Arizona, at an ambulatory clinic and at retail outlets with point-of-care services.
RESULTS. Theranos flagged tests outside their normal range 1.6× more often than other testing services (P < 0.0001). Of the 22 lab measurements evaluated, 15 (68%) showed significant interservice variability (P < 0.002). We found nonequivalent lipid panel test results between Theranos and other clinical services. Variability in testing services, sample collection times, and subjects markedly influenced lab results.
CONCLUSION. While laboratory practice standards exist to control this variability, the disparities between testing services we observed could potentially alter clinical interpretation and health care utilization. Greater transparency and evaluation of testing technologies would increase their utility in personalized health management.
FUNDING. This work was supported by the Icahn Institute for Genomics and Multiscale Biology, a gift from the Harris Family Charitable Foundation (to J.T. Dudley), and grants from the NIH (R01 DK098242 and U54 CA189201, to J.T. Dudley, and R01 AG046170 and U01 AI111598, to E.E. Schadt).
Brian A. Kidd, Gabriel Hoffman, Noah Zimmerman, Li Li, Joseph W. Morgan, Patricia K. Glowe, Gregory J. Botwin, Samir Parekh, Nikolina Babic, Matthew W. Doust, Gregory B. Stock, Eric E. Schadt, Joel T. Dudley
(A) Panel of test results displayed as a 2-dimensional heatmap. Each row represents one of the 60 subjects, and the columns aggregate the multiple measurements collected for each subject and testing service (6 measurement for Labs 1 and 2; 2 measurements for Theranos) (Lab 1, LabCorp; Lab 2, Quest Diagnostics). The column for each lab test is ordered from left to right by LabCorp, Quest, and Theranos. Colored squares indicate if at least one measurement is outside the normal range high (purple) or low (green). The horizontal bar chart alongside the rows of the heatmap reflects the percent of measurements outside the normal range at the individual level. All percentages represent 100× the number of measurements outside the normal range divided by the total number of measurements collected. (B) Comparison between percentage of tests outside the normal range across all subjects and multiple measurements for Theranos and the other labs (average of LabCorp and Quest). (C) Ratio of the tests outside their normal range — Theranos versus the mean value of LabCorp and Quest. Dashed horizontal line reflects a ratio of 1.6, which is the odds ratio for out-of-range tests between Theranos and the other labs. LDL ranges evaluated using normal LDL-C ranges and individual LDL-C measures reported directly by each provider. All comparisons made using reference ranges provided by individual testing services. Directly measured LDL values were used for Theranos.