Pharmacogenetic Testing Does Not Worsen Cardiovascular Disease Risk

Pharmacogenetic Testing Does Not Worsen Cardiovascular Disease Risk

Pharmacogenetic testing to assess a patient’s risk of statin side effects does not result in reduced cardiovascular health, shows research carried out at the VA Boston Healthcare System.

There is a variant in the SLCO1B1 gene that can cause muscular adverse effects when taking simvastatin to control high blood cholesterol. It is possible to take a test to see whether a person is a carrier of this variant before starting therapy, but the U.S. FDA and other regulatory authorities have suggested this might lead to poorer cardiovascular health in those that take the test.

To assess if this concern had merit, Jason Vassy, M.D., a researcher and clinician who splits his time between the VA Boston Healthcare System, Brigham and Women’s Hospital, and Harvard Medical School, and colleagues carried out a study of 408 patients to see if knowledge of test results before treatment would adversely influence cardiovascular disease risk.

The group had never taken statins before, but were at increased cardiovascular risk. Participants all received a SLCO1B1 gene variant test, but were then randomly split into a group of 193 who received their results at the beginning of the study, with results also given to their primary care physicians, and 215 controls who had their test results after 1 year.

The researchers assessed whether blood levels of low-density lipoprotein cholesterol, a marker of poor cardiovascular health that is reduced by statins, differed between the two groups at 1 year. As described in the journal JAMA Network Open, both groups saw a small drop in levels but there were no significant differences between them.

“This study provides reassurance that patients and providers can use pharmacogenetic testing in a way that maximizes its benefits while avoiding harmful unintended consequences,” said Vassy.

Overall, mutations increasing the risk of muscular adverse effects on taking simvastatin were found in 29% of the study participants. Statin prescriptions in both groups were similar at 32-34% and such prescriptions were given according to American College of Cardiology and American Heart Association guidelines.

Only one person was given simvastatin who had a SLCO1B1 variant indicating muscle adverse effects could occur and they were in the control group.

Testing everyone for the SLCO1B1 variant before starting statin therapy would be hugely expensive and could undermine the benefits statins can have. Vassy and colleagues are not suggesting everyone should have the test. However, their study shows that knowing that some drugs might be off the table does not mean that patients neglect their cardiovascular health.

“Many health care systems have launched pharmacogenetic testing programs,” said Vassy. “Our study offers empirical evidence that the clinical use of pharmacogenetic test results for SLCO1B1 do not worsen patient outcomes.”

“Such an absence of harm may reassure stakeholders contemplating the clinical use of pharmacogenetic information,” conclude the authors.