Resistant hypertension: resistance to treatment or resistance to taking treatment?
- Correspondence to Professor Morris J Brown, Clinical Pharmacology Unit, University of Cambridge, Addenbrookes Hospital, Cambridge CB2 2QQ, UK;
- Received 9 February 2014
- Accepted 18 February 2014
- Published Online First 2 April 2014
The treatment of hypertension has been a therapeutic success. A generation or more of effective drugs deserves considerable credit for their contribution to the substantial decline in age-related incidence of stroke, ischaemic heart disease and heart failure. And because almost all the drugs are long-since off patent, the cost of success comes cheaply. Indeed, National Institute of Health and Care Excellence (NICE) has branded treatment of hypertension as not only cost effective but cost saving.1 Yet not all patients achieve their blood pressure target and are labelled as ‘resistant hypertension’.
A contentious question has been whether resistant hypertension is a pathogenetic subset of hypertension, justifying a search for ‘stratified medicines’; or is it an imaginary condition caused by doctors in white coats and patients who do not take their tablets? On the one hand, there is abundant evidence that primary aldosteronism causes 20–25% of true treatment resistance.2 But Tomaszewski et al show that the ‘untakers’ (to create a simple noun for ‘patients who are non-adherent to their prescribed therapy’) account for an almost identical, high proportion of supposed resistant hypertension. Furthermore, the authors answer not only the question ‘Is my patient taking his/her tablets’, but also ‘How can I simply and cheaply find out?’.
Non-adherence to therapy, and its recognition, is a particular problem in hypertension because of its chronicity and asymptomatic nature (at least until drug treatment is started). To an extent, it can be assumed that few patients take every tablet every day and that our evidence from outcome trials of long-term efficacy is based on average consumption around the 70% level that some trials impose (via returned tablets counts) as an eligibility criterion. Omission of occasional, even frequent, doses of single drugs may be without consequence. After all, there is no evidence of superior outcome …