Even experts involved in clinical trials of the at-home saliva test say it has no place in routine clinical practice.
Experts question role for the genetic test, now promoted direct to consumers.
A small laboratory company, Boston Heart Diagnostics, has introduced and is promoting direct to consumers "the first and only at-home saliva laboratory developed test," which it says will help identify people who are likely to experience side effects from taking a statin.
The company claims the genetic test "helps patients understand how their bodies will process a statin and encourages them to discuss with their healthcare provider the type of statin that is best suited to their genotype."
But outside experts, including some who were recommended as a source for comment by Boston Heart Diagnostics itself because they have performed clinical trials with the new test, were highly critical of the test. They said there is no role for the test in routine clinical practice and that it should be used only in a research setting.
Gene Variant Testing
The test, called StatinSmart, costs $99. It analyzes the SLCO1B1 (Solute Carrier Organic Anion Transporter 1B1) gene for a variant that has been linked to statin-induced myopathy. The test, which has previously been available to physicians, is now being promoted directly to consumers, though the company will require "physician authorization" and will "include support for individuals to discuss their genotype result with their personal healthcare provider."
The company said it has now performed over 250,000 SLCO1B1 tests. They reported that one in four tests are positive for the mutation, which is comparable to earlier research. Boston Heart pointed out that as many as half of patients who start taking statins discontinue treatment within a year and that 60% of these "cite muscle pain as the primary reason for discontinuation."
Potential statin patients or current statin patients who have muscle pain can benefit from the test, the company maintained, because it will help tell the patients whether they have the gene variant. Patients who test positive, according to the company, might consider taking water-soluble statins like rosuvastatin (Crestor) or pravastatin (Pravachol), because the gene is less likely to play a role with these drugs.
In an interview, the CEO of the company, Susan Hertzberg said that "thousands of doctors" now use the test because "what we're doing now doesn't work." Most of the patients who stop taking statins "don't come back." Ernst Schaefer, MD, the company founder and Chief Medical Officer, said that "this test can improve treatment."
No Support For Routine Use
But outside experts said the test is not useful to either physicians or patients in clinical practice.
Boston Heart Diagnostics suggested that I contact researchers at Duke University who performed a study published in the Journal of the American College of Cardiology that helped confirm a role for SLCO1B1 in statin myopathy. But two of the researchers in the study told me that they did not see any current role for the test in clinical practice.
Geoffrey Ginsburg, MD, PhD, was the senior author of the JACC paper and is the director of the Center for Applied Genomics & Precision Medicine at Duke. He said he is "a big fan of understanding statin intolerance. This is a significant issue for optimizing our strategies for prevention of cardiovascular disease." He acknowledged that the test has "great promise to address this issue." But, he concluded, "clinical utility studies that show that genetic testing can direct patients, who are at risk for adverse reactions, to alternative therapies and increase adherence need to be done before there is widespread adoption of a genetic strategy."
Deepak Voora, MD, the first author of the JACC paper, also said the test was not ready for use in clinical practice, though he is in principle a strong believer in pharmacogenomics:
"We need to develop evidence. The onus is on us as investigators to develop the evidence that using genetic test information improves the lives of patients and improves health outcomes that patients care about. This is where the hype has gotten ahead of things. People are promoting pharmacogenetic testing without first developing the evidence that using this makes a difference in peoples' lives. And I'm a believer!"
Robert Eckel, MD, a former president of the American Heart Association, said that the current guidelines leave little room for routine use of the test. Currently, for people who don't tolerate a statin, the recommended step is to stop the statin and then rechallenge the patient with the same or a different statin. Knowing the genetic status of the patient would not change this process, said Eckel.
Sekar Kathiresan, MD, a cardiologist at Massachusetts General Hospital, said he didn't "see a clear role for this test in my clinical practice." He explained that, at 4%, "the positive predictive value of the test is very low. This means that of all those who come back with a positive test, only 4% will develop myopathy. So, most patients who have a positive test will not develop myopathy and will be incorrectly counseled about risk of statin."
All the outside doctors I spoke with also said that the best evidence for the importance of the genetic variant comes from people taking the high 80 mg dose of simvastatin (Zocor). But this dose is no longer used in clinical practice. The outside experts said that the evidence is weak for lower doses of simvastatin and for other statins, though the company maintains that there is evidence supporting broader use of the test.
Several of the outside experts said the test might be appropriate in individual cases in which the patient strongly wants the test. Eckel said the test didn't appear to cause any harm. Voora said, "That is why we are doing our clinical studies to weigh the risks vs. benefits of using this genetic test.”
Last updated 11.23.2015
This article was first published on MedPage Today and reprinted with permission from UBM Medica. Free registration is required.