Scientists at the Icahn School of Medicine at Mount Sinai compared basic blood tests run by commercial laboratories and found that the testing service and the time of collection significantly influenced results. Given that lab tests are used to help decide everything from disease diagnosis to whether a patient needs a medication or whether that medication is working, the new study highlights the importance of knowing the accuracy and variability of test results, according to the authors.
The research study, which was designed with data collected last July, analyzed results from comparable blood tests in healthy adults conducted at LabCorp, Quest Diagnostics, and Theranos. The researchers collected multiple samples from the same individuals and controlled for key variables, such as age, sex, and the time of blood collection, but they still found that more than half of the test results showed significant differences between test providers. Triglyceride levels and red blood cell counts were among the most consistent results, whereas white blood cell counts and overall cholesterol levels were among the most variable. Test results from Theranos’ finger-prick technology were flagged by Theranos as abnormal 1.6 times more often than those from LabCorp or Quest. Data from blood samples collected earlier in the day also showed significant differences compared with samples from the same subjects later in the day. The study was published in the Journal of Clinical Investigation.
“While most of the variability we found was within clinically accepted ranges, there were several cases where inaccurate results would have led to incorrect medical decisions,” said senior author Dr. Joel Dudley “We hope this study will inspire the biomedical community to take a critical look at all testing variables to ensure that lab results are as robust and reproducible as possible.”
The study focused on common blood tests, which typically return a single data point or a few data points. The new study, however, collected 14 samples to generate 22 lab results for each of 60 subjects, resulting in a total of more than 18,000 data points. While most results were within normal ranges, the researchers said, having even a small amount of inaccurate data mixed in could lead to erroneous conclusions from scientific or clinical studies.
“These testing disparities occurred despite rigorous laboratory certification and proficiency standards designed to ensure consistency,” said co-senior author Eric Schadt, PhD. “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.”
Source: Mount Sinai Hospital; March 28, 2016.