ABC | Volume 114, Nº6, June 2020

Original Article Velten Orthostatic hypotension and pressure variation: ELSA Arq Bras Cardiol. 2020; 114(6):1040-1048 for 3 minutes; 18 after 1 and 3 minutes, considering a reduction in one of the measurements in relation to the measurement in the supine position; 19 with seated participants; 20 after 1 minute; 3 after 1, 2, and 3minutes; 21 after 1, 2, and 5minutes; 22 considering a reduction in any measurement; measuring continuously, considering a reduction between 60 and 110 seconds; 23 and others. 11,24 The current guidelines recommend defining OH as a reduction in pressure within 3 minutes 6 after standing. There is, however, no consensus regarding the best moment within this period. In order to determine themost appropriatemoment, one study 25 evaluated 407 elderly patients (average age of 78.7±7.8 for patients withOH and 74.1±8.6 for patients without OH at 3 minutes) 1, 3, and 5minutes after standing. The prevalences were 21.86%, 21.37%, and 19.90%, respectively, and the parameters associated with OHwere the same during the three moments. It stands out that 29 elderly patients presentedOH only during the first minute, 18 only during the third, and 12 only during the fifth. The authors suggest adopting 1minute for use in clinical practice, because it requires less time (which is especially important in elderly patients) and identifies the majority of cases. It is worth noting that, were the definition of OH based on a reduction in pressure at any moment, the prevalence would be higher. Other studies 26,27 suggest longer evaluations, of up to 10 minutes, given that many participants develop OH in a delayed manner. In our study, with a lower average age (52.1±9.1 years), some participants also developed more delayed reductions in pressure, given that prevalence was higher at 3 minutes than that at 2, and it was highest at 5. It is necessary to use caution in interpreting data from continuous BP monitoring after standing. In these cases, a physiological decline in pressure may be expected after standing, especially in elderly patients, who are more susceptible to a sudden decrease in venous return and systolic output, until compensation mechanisms stabilize BP. Finucane et al. 10 observed stabilization within 30 seconds in individuals between 50 and 59 years of age and within over 30 seconds in older individuals. Keeping this initial reduction in mind, it may be inappropriate to consider a reduction at any moment as OH. Studies conducted in this manner have found very high prevalences, such as that of 58.6% found by Cooke et al. 17 These values must contain a large quantity of false positives. Cooke et al. 17 mention that, were they to consider sustained reductions in BP with a minimum duration of 60 seconds, the prevalence would drop to 23.3%, and it would be only 9% if they considered reductions sustained for 180 seconds. With these considerations regarding the heterogeneity of populations and methods, the comparison between studies should proceed cautiously. Studies in populations with age ranges similar to the ELSA-Brazil showed prevalences between 2.73% 5 and 7.4% 28 with the articles referring to to cohorts of the ARIC 4,5,28 and the Malmo Preventive Project (MPP) standing out. 1,2 The variations results from exclusions in the samples depending on the outcomes of each article. Most articles of the ARIC present a prevalence of approximately 5%. In all of them, the average age was around 53 years. The articles of the MPP present a prevalence of approximately 6% and very similar samples, with an average age of 48 years. It is noteworthy that studies on prevalence in individuals under the age of 45 are scarce. We found only one 20 with individuals from 18 to 100 years of age (average age of 49). However, the prevalence by age range was not mentioned. The increase in the prevalence of OHwith aging is linked to a series of causes. The followingmay be cited: changes in baroreflex function, inadequate vasoconstrictor responses, reduced cardiac and vascular compliance, decreased blood volume, and lower efficiency of skeletal muscles to act as a pump facilitating venous return. 29 Moreover, as age advances, the prevalence of arterial hypertension is greater, and this condition is associated withOH. This, however, does not appear to have occurred in our study, seeing that the pressure increase in the total population for in the ELSA-Brazil was similar to that observed in the subsample, in relation to both SBP and DBP (Table 2). In our population, in addition to age range, lower level of schooling also indicated a tendency to increase OH; this feature was observed both in the general sample and the subsample, with an attenuation in the latter group. It stands out that these differences in age are factors adjacent to these findings, given that groups with lower levels of schooling presented a higher average age (56.5 years in the category with lower schooling and 51.9 in the total population; in the subsample, these averages were 53.4 and 49.3 years, respectively). In relation to the presence of symptoms, we observed that the prevalence of OH was significantly higher when a symptom characteristic of a reduction in cerebral blood flowwas reported, especially when the reduction occurred in both pressures. In the Cardiovascular Health Study, 18 20% of individuals with OH presented symptoms, and, in the RotterdamStudy, 30 this indicator was 13.9%. These values are close to those detected in the ELSA- Brazil, confirming that OH is asymptomatic in most individuals. The presence of symptoms is relevant to indicate new diagnostic evaluations and make therapeutic decisions. In the meanwhile, there are no guidelines regarding clinical decision making in patients with OH who have no symptoms. 31 The distribution of pressures variation resulted in Z scores from −2 to −14.09 mmHg for SBP and −5.39 mmHg for DBP in the subsample of patients without hypertension (with or without medication), diabetes, history of heart failure, severe coronary disease, infarction, or stroke. Rose et al., 5 with a sample of 6,951 participants, following the exclusion of patients with hypertension, found a value similar in the fifth percentile of the reduction in SBP (−15.25mmHg), even using a different method. It is noteworthy that documents that defined OH 6,7 reported a cutoff point of −20 mmHg for SBP and −10 mmHg for DBP. Considering that the pressure variation presents a Gaussian distribution, the cutoff points currently recommended for defining the presence of OHwould go beyond those predicted by a standard statistical criterion, namely, considering excessive variation as individuals located in the 5% below the distribution of the curve. The definition of a cutoff point beyond this limit increases the probability of false negatives, or be it, individuals with OH who would not receive adequate diagnosis and advice depending on the establishment of cutoff points based on empirical and not experimental findings. In relation to the prevalence of OH, considering the criterion of a reduction of ≥30 mmHg in patients with hypertension, a 1046