ABC | Volume 115, Nº1, July 2020

Original Article Macedo et al. Resistant hypertension in afrodescendants Arq Bras Cardiol. 2020; 115(1):31-39 controlling SAH in black women. 28 In a population study carried out in Sweden, Holmqvist et al. 31 also reported that women had a higher prevalence of RH, except when they specifically assessed the subgroup with controlled RH. 31 The present finding of a higher proportion of women in our sample of individuals with HR should be interpreted with caution, as it can be overestimated by Brazilian cultural aspects, since women tend to seek more health care. 18 However, this fact can identify a problem that deserves more attention, in order to encourage a better clinical evaluation and the antihypertensive therapy used in these individuals. In contrast, some authors reported a higher prevalence of RH among men. 32 Regarding therapy, there was a wide use of the various classes of antihypertensive drugs available and a large proportion of participants used the combination of ACEi or ARB, CCB and thiazide diuretic, as recommended in the literature. 2,9 This combination was prescribed more frequently in patients with RfH, probably due to the greater difficulty in obtaining BP control in these patients. The prescriptions of spironolactone as the fourth drug to be introduced in antihypertensive therapy as well as the option of chlortalidone as the thiazide diuretic of choice, due to its longer duration, have also been recommended in the literature. 2,3,33,34 Some authors even suggest that the use of these drugs should participate in the definition criteria for RfH. 27 In our study, approximately one third of patients were receiving chlortalidone, while almost half were using spironolactone. Both were used significantly more frequently in patients with RfH (47.9% of patients with RfH used chlortalidone and 77.5% spironolactone, versus 11.5 and 22.5% of those with RH, respectively), which may corroborate a probable adequate RfH classification in a good number of patients. The relatively low preference for chlortalidone as a thiazide diuretic can be justified by the fact that it is a public service and the drug does not participate in the government list of free distribution of antihypertensive drugs, while hydrochlorothiazide is distributed free of charge. It is also possible that some of the participants are not using spironolactone due to adverse effects and/or contraindications for this medication. However, the frequency of use of chlortalidone and spironolactone in our work was somewhat similar to that of other studies. 7,8,14,16 However, there is a clear need to encourage more frequent use of these drugs, which, according to current evidence, would be more suitable for the treatment of RH. Due to its transversal characteristic, our study has some limitations, since it is not possible to establish a causality and temporality relationship between some associations found, for example, a higher prevalence of stroke among those with RfH. The data presented here, however, have value in raising hypotheses to be proven in longitudinal studies with greater statistical power. This convenience sample is derived from a population seen at a referral clinic for severe hypertensive patients, with high CVR, and may have overestimated the prevalences and associations described. Another important aspect refers to the fact that some patients with pseudoresistance may have been included, which could also overestimate the prevalences found. However, these patients are followed up in a specific outpatient clinic, most of them for a long period (over 10 years, on average) and with an average time of diagnosis of hypertension for more than 20 years. They undergo frequent reassessments, including ABPM 35 and the Morisky score, 25 to assess the white coat effect and adherence to therapy, respectively. This could minimize the occurrence of individuals with pseudoresistance in this sample. Some other important studies, however, have evaluated patients with resistance to the treatment of SAH, defining them as resistant or apparent refractory hypertensive individuals and have found relevant associations. 10,36,37 The classification of individuals according to skin color was self-reported, as recommended in studies in Brazilian populations that involve this variable, 38 could lead to bias, due to the great ethnic mix of the Brazilian population. However, the ethnic profile of the sample studied is consistent with that of the local population and Figure 3 - Proportion of concomitant use of chlortalidone and spironolactone, according to resistant or refractory hypertension. HR: resistant hypertension; HRf: refractory hypertension; P <0.001; for the difference in frequency of the use of chlortalidone between HR versus HRf; P <0.001; for difference in frequency of spironolactone use between HR versus HRf. 90 Concomitant use of chlortalidone and spironolactone (%) 80 70 60 50 40 30 20 10 0 Chlortalidone 15.5 (N = 11) 47.9 (N = 36) 22.5 (N = 16) 77.5 (N = 56) Spironolactone RH RfH 36