116 Antihypertensive drug concordance in patients with apparent resistant hypertension: a tertiary hypertension referral centre experience

Introduction Individuals with resistant hypertension have a 50% greater risk of cardiovascular events (death, myocardial infarction, heart failure, stroke or chronic kidney disease) compared to those with well-controlled hypertension. Non-adherence to antihypertensive medication is a major cause of uncontrolled hypertension, with rates reported as high as 84%. The aim of this study was to assess the prevalence of non-adherence in hypertensive individuals referred to a tertiary hypertension centre in South of London (Blood Pressure Unit, St George’s University Hospital NHS foundation Trust). Methods After the optimisation of drug regimens and the exclusion of white coat and secondary hypertension, drug adherence was assessed using liquid chromatography–mass spectrometry (LC-MS) analysis of urine samples in 124 individuals who met the criteria for resistant hypertension (uncontrolled hypertension despite concurrently taking at least 3 antihypertensive drugs of different classes including a diuretic or hypertension controlled on 4 drugs). All included subjects confirmed adherence to their prescribed antihypertensive medication on several occasions, whilst individuals who admitted to missing their drugs were excluded from the study. Results Non-adherence was found in 71 individuals (57.3%). Of these 45 (63.4%) had partial non-adherence and 26 (36.6%) had complete non-adherence. Non-adherent individuals were significantly younger in age, had a shorter history of hypertension, more likely to be a female (OR: 3.07; 95% CI: 1.45–6.47; p=0.003) and have depression (OR: 11.66; 95% CI 1.47–92.19; p=0.004), and less likely to have concomitant cardiovascular disease (OR: 0.42 95% CI 0.19–0.92; p=0.028), type 2 diabetes mellitus (OR: 0.40; 95% CI: 0.19–0.83; p=0.013), chronic kidney disease (OR: 0.34; 95% CI 0.12–0.92; p=0.028) and retinopathy (OR: 0.14; 95% CI 0.04–0.51; p=0.001). Low levels of adherence were observed more for individuals on diuretics. Conclusion In individuals with apparent resistant hypertension, poor adherence to antihypertensive therapy is very common and was observed in 57% of individuals despite their insistence of their treatment adherence in the preceding days. The assessment of adherence at an early stage in individuals with apparent resistant hypertension is essential for tailoring treatment strategies and for saving vital healthcare resources. Conflict of Interest None