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Wide Variation Found in Consumer Blood Tests

Drop of blood on finger

(Alden Chadwick, Wikimedia Commons

29 March 2016; updated. Researchers at a New York medical center found some wide differences in results from commercial blood tests marketed to consumers, with samples from 60 healthy adults. The team led by Mount Sinai Medical Center bioinformatics professor Joel Dudley and genomics professor Eric Schadt published their findings yesterday (28 March) in Journal of Clinical Investigation.

Dudley, Schadt, and colleagues sought to assess the reliability of blood testing services marketed directly to consumers. While most clinical lab tests are requested by physicians, more individuals are taking an active role in their own medical decisions, suggesting the number of people using these services is likely to increase.

One company, Theranos Inc. in Palo Alto, California, designs its services specifically for individual consumers, although its tests can also be ordered by physicians. Theranos blood tests require only a drop of blood from a fingerprick, instead of blood drawn from a vein, and cost a fraction of tests done by commercial labs.

The Mount Sinai team evaluated the Theranos tests with comparable tests by LabCorp and Quest Diagnostics, two of the largest commercial clinical labs in the U.S. The researchers recruited 60 healthy individuals in Phoenix, Arizona in July 2015. Each of the 60 participants provided 14 blood samples required by the labs, which were used in 22 different clinical lab tests, giving 2,640 individual test results for Theranos, and 7,920 separate results each for LabCorp and Quest Diagnostics.

While the findings show some similarities in test results, more than half of the results show statistically reliable differences among the three services, even after controlling for factors including age, sex, and time of collection. The analysis shows agreement in results for triglycerides — fats in the blood — and red blood cell counts. In 15 of the 22 tests, however, the testing services returned varying results, enough for the differences to be statistically reliable. These varying results included white blood cell counts, average volumes of red blood cells, and a number of measures for cholesterol levels.

Theranos’s tests were more likely to highlight potential health problems than the other two services. Tests done by Theranos returned results flagged as abnormal 1.6 times more often, than tests by LabCorp and Quest. Theranos returned 12 percent of their measurements outside normal reference ranges, while LabCorp and Quest each reported 8 percent as abnormal, a statistically reliable difference. The researchers found Theranos’s results for cholesterol and low- and high-density lipoprotein values systematically different from LabCorp and Quest, which could have implications for clinical decisions.

The time of day blood tests were taken appears to influence some of the variations. In 13 of the 22 tests, researchers found differences in results taken earlier in the day compared to later on. Phosphorus levels in blood serum, white blood cell counts, and leukocyte measures of immune system health tended to be higher later in the day. Measures of uric acid levels in serum, total cholesterol, high-density lipoprotein, red blood cell counts and properties, and bilirubin levels indicating potential liver problems were generally higher with blood tests taken earlier in the day.

The authors recommend a closer look at blood tests marketed directly to consumers. “While most of the variability we found was within clinically accepted ranges,” says Dudley in a Mount Sinai statement, “there were several cases where inaccurate results would have led to incorrect medical decisions.” Schadt adds, “Our results suggest the need for greater transparency in lab technologies and procedures, as well as a much more thorough investigation of biological mechanisms that may contribute to more dynamic levels than we currently understand.”

The study was funded by Mount Sinai medical center. None of the researchers reported financial interests in clinical lab testing enterprises. Dudley is a shareholder in NuMedii, a company applying big-data analytics to drug discovery, while Schadt is a scientific advisor to that company.

At the time of this post, none of the companies mentioned in the study issued comments on the results. Science & Enterprise asked each company for comments, which we will add to this report.

Update 1, 29 March 2016. Pattie Kushner, LabCorp’s vice-president for corporate communications, sent the following comment to Science & Enterprise …

All tests performed by LabCorp in connection with this study were handled according to our routine processes and protocols. The tests performed by LabCorp that were used in this study are all FDA-cleared or approved, and the result ranges developed during validation were part of the FDA’s review process before the tests became available for patient use. There is normal and acceptable variability for test results within specified ranges established as part of the regulatory process and pursuant to guidelines issued by regulatory and accrediting entities such as CLIA and the College of America Pathologists (CAP).

The samples submitted for testing were collected over an extended period of time, which the study acknowledges can contribute to result variability. Although the study made efforts to account for that, it is not clear whether those efforts were adequate. In addition, the quality of the specimen collection itself can also cause variability in test results, and it should be noted that LabCorp did not collect the specimens that were submitted to us for testing. Even without being able to fully account for those factors, the study shows that the results of the tests performed by LabCorp are well within established guidelines and meet performance expectations. Test quality relies on many factors, perhaps most importantly on the proficiency of each person involved in the testing process.

LabCorp is extremely proud of our dedicated, professional employees, and because of them our world-class diagnostics are relied on by physicians and patients to provide consistent, high-quality results that help to improve care and improve lives.

Update 2, 29 March 2016. Theranos posted a letter to Journal of Clinical Investigation that published the study.

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