Measuring, analyzing, and managing drug adherence in resistant hypertension.

T he management of hypertension is based on 2 major approaches: a modification of lifestyle and the lifelong prescription of antihypertensive drugs. 1,2 All hypertension guidelines recognize that " …the most effective therapy prescribed by the most careful clinician will control hypertension only if the patient is motivated to take the prescribed medication and to establish and maintain a health-promoting lifestyle. " This statement clearly emphasizes the importance of supporting drug adherence (ie, adherence to the prescribed dosing regimens for prescribed medications) for patients to gain the maximal benefits of their therapy. Unfortunately, drug adherence in cardiovascular prevention remains low in the population. Thus, in a recent meta-analysis of data on 376 162 patients from 20 studies assessing drug adherence using prescription refill frequency for 7 preventive drug classes (aspirin , statins, and 5 antihypertensive drug classes) prescribed for primary and secondary prevention of cardiovascular diseases, mean adherence over all studies was only 57% after a median of 2 years. Furthermore, mean drug adherence was substantively and statistically significantly lower in primary than in secondary prevention. 3 The role of drug adherence is particularly relevant in clinical situations in which drug therapies do not provide the expected results. This is typically so in resistant hyper-tension, commonly defined as the failure to reach blood pressure goals in patients adhering to adequate or maximal doses of an appropriate 3-drug regimen that includes a diuretic. Obviously, this definition of resistant hyperten-sion implies that patients fully adhere to their therapy. This might actually be one of the reasons why the true prevalence of patients with resistant hypertension in the population remains largely ambiguous. In clinical trials, 10% to 30% of patients are estimated to present with resistant hyperten-sion. 6 In the National Health and Nutrition Examination Survey conducted between 2003 and 2008, 8.9% of all US adults with hypertension and 12.8% of the treated hyperten-sive population met the criteria of resistant hypertension. 7 A large Spanish survey has recently examined the clinical characteristics of patients with resistant hypertension and found it to be present in 12% of the treated population, although approximately one third of these patients had a white-coat hypertension during ambulatory blood pressure (BP) monitoring. 8 These 2 studies included in their evaluation patients with controlled resistant hypertension (ie, patients controlled on ≥4 medications). The cardiovascular risk profile of resistant hypertensive patients was higher than in nonresistant patients. Interestingly, in none of …