Some people with high blood pressure seem resistant to treatment. They may be prescribed additional medications or undergo special procedures. In many cases, they just might not be taking their pills properly.
Individuals with high blood pressure are often prescribed antihypertensives because they are effective and often affordable. Still, many with high blood pressure and other heart conditions do not take their medications as directed.
A new study confirmed this notion. By using a simple urine test, researchers discovered that about one in four individuals with high blood pressure were not taking their prescriptions at all or skipping them at least part of the time.
Maciej Tomaszewski, MD, from the Department of Cardiovascular Sciences at the University of Leicester in England, and colleagues analyzed urine samples from 208 patients with high blood pressure who were prescribed antihypertensives.
Using a widely available technique called high performance liquid chromatography-tandem mass spectrometry, or HP LC-MS/MS, Dr. Tomaszewski and team screened urine samples for the 40 most commonly prescribed blood pressure medications.
Based on the urine results, these researchers observed that a quarter of patients were partially or completely not sticking to their treatment regimen. About one in ten were failing to take their pills at all, while about one in seven were lapsing and only taking their medications some of the time.
The researchers noted a direct link between blood pressure readings and the number of medications detected in the urine. Individuals taking all their prescribed medications had lower blood pressure readings.
The greatest proportion of those not taking their medication at all (one in four) was among 17 subjects who had been referred for renal denervation.
Some doctors recommend renal denervation for patients who have been diagnosed with treatment-resistant high blood pressure. For the procedure, a trained medical professional cauterizes nerve endings in the kidney artery walls using a guidable catheter with a radio frequency (RF) energy electrode tip. While denervation has been shown to lead to a blood pressure–lowering response, questions remain about the procedure’s effectiveness.
This study showed that some of these denervation procedures may be unnecessary because about one in four of these patients were not necessarily treatment-resistant; they simply were not taking their medications.
"That most patients do not take all their drugs all the time was probably predictable," wrote Morris Brown, MD, of the Clinical Pharmacology Unit at the University of Cambridge, in a corresponding editorial. "But that 23 percent of those referred for renal denervation have no detectable drug in their urine was a shock."
The study's authors concluded, “Screening for non-adherence to antihypertensive treatment [by this type of urine analysis] is a simple, non-invasive diagnostic test with a potential to better stratify patients prior to treatment escalations and expensive and irreversible procedures such as renal denervation.”
This study was published online April 2 in the journal Heart.