High rates of non-adherence to antihypertensive treatment revealed by high-performance liquid chromatography-tandem mass spectrometry (HP LC-MS/MS) urine analysis

TLDR

Non‑adherence to antihypertensive therapy is a major contributor to uncontrolled blood pressure, is common especially among patients with poor control or renal denervation referrals, yet reliable routine detection tools are scarce. The study aimed to determine the prevalence of antihypertensive non‑adherence and its impact on blood pressure using a simple urine‑based assay. The authors screened 40 antihypertensive drugs or metabolites in spot urine samples from 208 patients using high‑performance liquid chromatography‑tandem mass spectrometry. Overall, 25 % of patients were non‑adherent (10.1 % total, 14.9 % partial), with the highest rates among poorly controlled follow‑up patients (28.8 %) and renal denervation referrals (23.5 %); each additional missed medication was associated with a ~3‑mmHg rise in systolic BP, and the assay can identify non‑adherence to guide further care.

Abstract

Non-adherence to therapy is an important cause of suboptimal blood pressure control but few practical tools exist to accurately and routinely detect it. We used a simple urine-based assay to evaluate the prevalence of antihypertensive treatment non-adherence and its impact on blood pressure in a specialist hypertension centre.208 hypertensive patients (125 new referrals, 66 follow-up patients with inadequate blood pressure control and 17 renal denervation referrals) underwent assessment of antihypertensive drug intake using high-performance liquid chromatography-tandem mass spectrometry (HP LC-MS/MS) urine analysis at the time of clinical appointment. A total of 40 most commonly prescribed antihypertensive medications (or their metabolites) were screened for in spot urine samples.Overall, 25% of patients were totally or partially non-adherent to antihypertensive treatment (total non-adherence 10.1%, partial non-adherence 14.9%). The highest prevalence of partial and total non-adherence was among follow-up patients with inadequate blood pressure control (28.8%) and those referred for consideration of renal denervation (23.5%), respectively. There was a linear relationship between blood pressure and the numerical difference in detected/prescribed antihypertensive medications-every unit increase in this difference was associated with 3.0 (1.1) mm Hg, 3.1 (0.7) mm Hg and 1.9 (0.7) mm Hg increase in adjusted clinic systolic blood pressure, clinic diastolic blood pressure (DBP) and 24 h mean daytime DBP (p=0.0051, p=8.62 × 10(-6), p=0.0057), respectively.Non-adherence to blood pressure lowering therapy is common, particularly in patients with suboptimal blood pressure control and those referred for renal denervation. HP LC-MS/MS urine analysis could be used to exclude non-adherence and better stratify further investigations and intervention.