High rates of non-adherence to antihypertensive treatment revealed by high-performance liquid chromatography-tandem mass spectrometry (HP LC-MS/MS) urine analysis
- Maciej Tomaszewski1,2,
- Christobelle White1,2,
- Prashanth Patel3,
- Nicholas Masca1,2,
- Ravi Damani1,
- Joanne Hepworth3,
- Nilesh J Samani1,2,
- Pankaj Gupta1,3,
- Webster Madira3,
- Adrian Stanley1,3,
- Bryan Williams4
- 1Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- 2NIHR Leicester Biomedical Research Unit in Cardiovascular Disease, Leicester, UK
- 3Department of Chemical Pathology, University Hospitals of Leicester NHS Trust, Leicester, UK
- 4Institute of Cardiovascular Science and NIHR University College London Hospitals Biomedical Research Centre, University College London, London, UK
- Correspondence to Dr Maciej Tomaszewski, Department of Cardiovascular Sciences, University of Leicester, Clinical Sciences Wing, Glenfield Hospital, Leicester, LE3 9QP, UK;
- Received 7 October 2013
- Revised 7 January 2014
- Accepted 14 January 2014
- Published Online First 2 April 2014
Objectives 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.
Methods 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.
Results 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.
Conclusions 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.
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