Apparent treatment resistant hypertension in primary care: the feasibility of assessing adherence to therapy with mass spectrometry-urine analysis in combination with ambulatory blood pressure monitoring.
Apparent treatment resistant hypertension (aTRH) is defined as poorly-controlled blood pressure (BP) in patients taking three or more anti-hypertensive medications (one of which must be a diuretic). The term apparent is used because some patients will have true treatment resistant hypertension, some undiagnosed secondary hypertension, whilst others are pseudo-resistant. Pseudo-resistance occurs when non-adherence to medication, white coat hypertension (WCH), lifestyle and inadequate drug dosing are responsible for the poorly controlled BP.
Our aim is to determine among patients with aTRH in primary care, the feasibility of using mass spectrometry-urine analysis combined with ambulatory blood pressure monitoring (ABPM) to examine pseudo-resistance.
For this purpose, 453 patients with aTRH, from a baseline population of 45,788 persons, in fifteen university-research affiliated general practices were invited to participate.Eligible patients underwent mass spectrometry-urine analysis to test adherence to medications and ABPM.
In total, 235 urine samples underwent mass spectrometry-urine analysis confirming feasibility. Of these, 174 (74%) patients were fully adherent, 56 (24%) partially adherent, and 5 (2%) fully non-adherent. ABPM reports were also analysed (n=206) and 58 (28%) patients had WCH. No significant associations were found between adherence and socio-demographics, drug class, or BP.
Pseudo-resistance is common, and mass spectrometry-urine analysis combined with ABPM is feasible in primary care. This unique approach may well yield savings for healthcare programs through maximizing BP control in high risk populations and improving prognosis. Further research on how to incorporate this approach into individual patient consultations and its associated cost-effectiveness is now appropriate.