ABC | Volume 115, Nº1, July 2020

Original Article Macedo et al. Resistant hypertension in afrodescendants Arq Bras Cardiol. 2020; 115(1):31-39 hypertension. 6,15,16 In black individuals, hypertension tends to manifest itself more severely, presenting greater difficulty in control and greater probability of complications and damage to target organs. 17 There is, however, a gap in the literature in the evaluation of the association between RH and individuals of African descent, 18 which can be attributed to genetic, environmental or even local factors. 7,19,20 The present study aims, therefore, to compare clinical and epidemiological characteristics and prevalence of cardiovascular events in people of African descent diagnosed with RH or RfH. Improving the knowledge of these characteristics in this specific population, including demographic, social, ethnic aspects, conditions of access to health services and distribution of medicines, may contribute to the planning of strategies aimed at reducing the negative impact of this important clinical condition on the health of these individuals. Methods This is a cross-sectional study, carried out in a reference outpatient clinic for Severe Hypertensive Cardiovascular Disease at a University Hospital in the city of Salvador, Bahia. The population consisted of adult patients with a diagnosis of RH followed up regularly at the clinic between November 2012 and December 2015. The sample was made by convenience, being consecutively selected during routine visits all patients who agreed to participate in the study, signing an informed consent form. The study was approved by the local Ethics Committee, complying with resolution 466/12 of the National Supplementary Health Agency ( Agência Nacional de Saúde Suplementar – ANS). Patients with uncontrolled BP (systolic blood pressure – SBP 140mmHg and/or diastolic blood pressure – DBP 90mmHg) were considered as having HR, despite the use of three antihypertensive drugs with synergistic actions at the maximum recommended and tolerated doses, being one of them preferably a thiazide diuretic, or those with controlled BP, using 4 synergistic antihypertensive drugs and in adequate doses, including also a thiazide diuretic. 2 Patients with SBP≥140mmHg and/or DBP≥90mmHg using five or more classes of antihypertensive drugs were considered to have RfH. 7 Blood pressure was measured during a routine medical consultation, after five minutes of rest, with the back supported in a sitting position, legs not crossed and the arm supported at heart level. Two measurements were taken, one before and one after the interview, with a minimum interval of five minutes. The average of the two measurements was used as a reference value for the patient’s BP. The measurements were performed with an Omron HEM 711 DLX automatic oscillometric sphygmomanometer, validated by the British Hypertension Society (BHS) and the Association for Advancement of Medical Instrumentation (AAMI). 21,22 A trained team collected, through a structured interview and review of medical records, information on demographic and clinical data, clinical-cardiological evaluation, history of cardiovascular events, medications, laboratory tests and factors related to lifestyle. Cardiovascular risk (CVR) was estimated by the Framingham risk score (FRS). Ethnicity was self-declared according to Brazilian standards of white, black or brown. The presence of previous cardiovascular events was defined by a positive history of stroke (stroke) or acute myocardial infarction (AMI) reported by the participant or family member and/or when present in the medical record. The glomerular filtration rate (GFR) was estimated using the Cockcroft-Gault equation (GFRe-CG). 23 For individuals with overweight or obesity, the correction factor suggested by Saracino et al. (GFRe-CGcorrected). 24 Renal function was considered abnormal when GFR<60 ml/min. For the classification of overweight and obesity, the value of body mass index (BMI) greater than 25 and 30 kg/m², respectively, was considered. As part of the care and follow-up protocol, at least an Ambulatory Blood Pressure Monitoring (ABPM) is performed to assess the possibility of the white coat effect as a cause of possible pseudo-resistance to the treatment of SAH. The Morisky questionnaire (MMAS-8) was used to assess adherence to therapy. The level of adherence was determined by the score resulting from the sum of all correct answers: high adherence (8 points), average adherence (6 to <8 points) and low adherence (<6 points). 25,26 Statistical analysis For statistical analysis, Microsoft Office Excel 2010 software and SPSS (version 20.0) were used. A univariate descriptive analysis of the characteristics of the investigated population and a bivariate analysis (Pearson’s χ 2 test) were performed to estimate the association between the dependent variable (RH or RfH) and the main independent variable (Presence of Atherosclerosis, Left Ventricular Hypertrophy and Events Cardiovascular – AMI or stroke). The continuous variables studied (SBP, DBP, time of diagnosis of SAH and time of outpatient follow-up) showed normal distribution by the Kolmogorov-Smirnov test and were compared between the RH and RfH groups using the unpaired Student’s t -test. Categorical variables have their frequencies represented in percentages and continuous variables are presented in their means and standard deviation. The level of significance was set at 5%. Results 146 patients were evaluated, of which 68.7% were female and 88.4% were of African descent (mixed race and black), with a mean age of 61.8 ± 12.1 years. The mean time since the diagnosis of hypertension was 21.2 ± 12.5 years (median = 18 years), and patients had been followed at the clinic for an average of 11.1 ± 8.5 years (median = 10 years) ). There was a high prevalence of risk factors for cardiovascular disease: 34.2% of individuals had diabetes mellitus , 69.4% dyslipidemia, 36.1% obesity, 38.3% history of smoking and 61% moderate risk/high risk for events cardiovascular diseases by the FRS. History of previous AMI was found in 21.8% of participants and stroke in 19.9%. Abnormality of renal function (GFR<60mL/min) was identified in 34.2%. SBP was considered controlled in 29.5% and DBP in 50.4% of 32