Clinical Heart and Vascular Center

Statin Nonadherence and Therapeutic Drug Monitoring

By Wanpen Vongpatanasin, M.D., Professor of Internal Medicine; Director, Hypertension Section

Vongpatanasin Headshot

Patients often do not adhere to their prescribed medication regimen. This lack of adherence is a major challenge encountered by clinicians when treating patients with hypertension. An increasing number of studies show that adherence monitoring by detection of a drug or its metabolites in blood or urine samples, a strategy known as therapeutic drug monitoring (TDM), is more reliable for detecting nonadherence as compared to patient self-reporting or patients completing a detailed questionnaire. 

“We found … that 40% of patients did not take cholesterol-lowering drug medications (i.e., statins) despite having high 10-year cardiovascular risks (more than 10%).”

Wanpen Vongpatanasin, M.D.
Vongpat Stock

At the AHA Scientific Sessions, we presented data from our study assessing adherence via TDM in patients with uncontrolled hypertension who were treated at the Parkland Memorial Hospital cardiology clinic. Our TDM assessment found that approximately 20% of patients did not take at least one BP medication regularly as prescribed. Furthermore, we found that 40% of patients did not take cholesterol-lowering drug medications (i.e., statins) despite having high 10-year cardiovascular risks (more than 10%). Finally, we found that pharmacy refill data alone had limited specificity of 63% in predicting adherence as compared to an assessment via TDM. Overall, these data suggest that TDM may be a useful tool to assess adherence in patients with poorly controlled hypertension. Additional studies are needed to determine how best to improve adherence to cardiovascular medications in this high-risk patient population.

Read more articles from our Physician Update AHA Edition.