- Email: [email protected]
Use of noninvasive procedures in the cardiovascular risk assessment of hypertensive and normotensive individuals
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Use of noninvasive procedures in the cardiovascular risk assessment of hypertensive and normotensive individuals Adrielle Naiara Toneti, RN, Dayana Freitas, RN, Patrıcia Magnabosco, PhD, Bruna Francielle Toneti, Student, Daniel Martinez Lana, PE, Simone de Godoy, PhD, and Leila Maria Marchi-Alves, PhD
Background: Arterial hypertension is associated with a high prevalence of vascular alterations. The use of noninvasive procedures to assess peripheral arterial diseases in the ranking of cardiovascular risks has been increasingly valued in clinical practice and should be adopted in nursing. Objective: To identify the cardiovascular risk of hypertensive and normotensive individuals through the use of different noninvasive procedures to assess the vascular function and integrity: ankle-brachial index, pulse pressure, and delta brachial-brachial and delta ankle-brachial indexes. Methods: Quantitative, descriptive, and cross-sectional study undertaken at a health service in a Brazilian city. The research variables were age, sex, blood pressure, abdominal circumference, body mass index, ankle-brachial index, pulse pressure, and delta brachial-brachial and delta ankle-brachial indexes. Results: Fifty-four (43.1%) normotensive and 69 (56.9%) hypertensive individuals participated in the study. Alterations were identified in ankle-brachial index, corresponding to mild and moderate arterial obstruction, among hypertensive individuals only (7.2%), with higher pulse pressure indices (P < 0.0001). The assessment of the correlation between the ankle-brachial index and pulse pressure showed no correlation in the normotensive group and a statistically significant correlation among hypertensive patients (Pearson’s coefficient = 0.45, P < 0.0001, r2 = 0.21). A statistically significant difference (P < 0.05) was found in the analysis of the mean delta brachial-brachial (6.2 0.71 mm Hg for normotensive and 10.16 1.45 mm Hg for hypertensive individuals) and delta ankle-brachial index (0.06 0.01 for normotensive and 0.11 0.01 for hypertensive individuals). Conclusions: The use of the proposed cardiovascular risk predictors shows more frequent alterations among hypertensive than normotensive individuals. (J Vasc Nurs 2016;34:17-23)
In the last two centuries, as a result of the changes derived from the epidemiologic and demographic transition processes, nontransmissible chronic diseases and their complications have become increasingly frequent, including cardiovascular diseases (CVDs),1 which represent the main cause of death all over the world and represent about 30% of global deaths and 20% of all deaths in individuals aged older than 30 years in Brazil.2,3 Hypertension is one of the main CVDs and is also considered a relevant risk factor for the occurrence of other morbid events. The From the University of S~ao Paulo at Ribeir~ao Preto College of Nursing, Ribeir~ao Preto, SP, Brazil; Federal University of Uberl^andia, Uberl^andia, MG, Brazil; General and Specialized Nursing Department, University of S~ao Paulo at Ribeir~ao Preto College of Nursing, Ribeir~ao Preto, SP, Brazil. Corresponding author: Leila Maria Marchi-Alves, PhD, General and Specialized Nursing Department, University of S~ao Paulo at Ribeir~ao Preto College of Nursing, Av. dos Bandeirantes, 3900, Bairro Monte Alegre, CEP: 14.040-902, Ribeir~ao Preto, SP, Brazil (E-mail: [email protected]). 1062-0303/$36.00 Copyright Ó 2016 by the Society for Vascular Nursing, Inc. http://dx.doi.org/10.1016/j.jvn.2015.10.001
boundary that defines hypertension considers systolic blood pressure (SBP) $140 mm Hg and⁄or diastolic blood pressure $90 mm Hg when measured in the doctor’s office. It is estimated that 1.56 billion adults will be living with hypertension in 2025, which is why the disease is qualified as an increasing and global public health problem.4 In Brazil, the prevalence of hypertension ranges between 22.3% and 43.9% of the population.5 Recently, many studies have appointed the effective use of noninvasive procedures for the clinical assessment of cardiovascular risk, including the measuring of the ankle-brachial index (ABI) and the determination of the pulse pressure (PP).6-8 The ABI is a noninvasive measure to detect blood pressure changes in the lower limbs, being a simple and cost-effective method.9 In Brazil, measuring the ABI is indicated for individuals aged $70 years or individuals aged between 50 and 69 years with clinical characteristics and risk factors specified in the Brazilian Hypertension Guidelines (2010).5 According to the Brazilian guidelines, the ABI is considered normal when superior to 0.90; lower levels indicate arterial obstruction.5 Despite these recommendations, this method has not been applied in daily clinical practice, which can be justified by the need to use specific equipment and training.10 The American Heart Association encourages the exploration of more feasible alternative methods for routine ABI assessment in clinical practice, with a view to reducing the application costs
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and enhancing its implementation in primary health care.11 From that perspective, studies have demonstrated the efficacy of using automated oscillatory sphygmomanometers (AOS) to determine the ABI,7,10 which for many years was restricted to the use of the vascular Doppler only. More recently, nurses have been developing research, demonstrating satisfactory results when this resource is used.10,12,13 Arevalo-Manso et al10 observed that the sensitivity and specificity of an automatic blood pressure device detecting ABI <0.90 shows acceptable levels when nurses perform the technique. Nelson et al12 determined the level of agreement between a conventional ABI measurement (using Doppler and mercury sphygmomanometer taken by a research nurse) and ABI measure (using an oscillometric device taken by a practice nurse). They concluded that the ABI measure using automated equipment may be used as a screening tool for high risk and CVDs of patients in primary care. Romero-Vilaplana et al13 showed that the assessment of ABI should be part of the exploration of chronic patients who come periodically to nursing consultations, particularly those ones with a moderate or high cardiovascular risk. To look for alternatives applicable to the clinical routine of cardiovascular risk assessment, Kawamura,7 departing from the premise that the similarity between the sides of the human body should assume highly similar pressure levels, except in case of anatomic–pathologic abnormalities, elaborated two new risk assessment forms, obtained when the blood pressure and ABI are measured: the delta brachial-brachial index (delta-BB) and the delta ankle-brachial index (delta-ABI). These innovative assessment forms, when altered (>8 mm Hg for delta-BB and >0.13 for delta-ABI), showed very high prevalence levels in patients having peripheral arterial disease (PAD), constituting an interesting complementary cardiovascular risk assessment method that can be further explored in future studies. Besides the use of the clinical indicators mentioned, the PP should also be highlighted, being a useful predictor of coronary artery disease or total CVD, mainly in middle-aged or elderly people.14,15 Investigators also suggest PP as a marker of preclinical CVD.16 The use of noninvasive procedures to assess atherosclerosis in the cardiovascular risk ranking has been increasingly valued, especially the use of ABI.17 In the literature, recommendations are found for research that combines the use of different noninvasive procedures to assess the vascular function and integrity, as the different measuring methods reflect the distinct stages of the vascular alteration process that leads to cardiovascular events.18 Based on the importance and increasing use of these clinical indicators to identify cardiovascular risks, the objective in this study was to identify the cardiovascular risk in hypertensive and normotensive individuals through the determination of the ABI, PP, and delta-BB and the delta-ABI, using AOS. Altered levels of the research variables are expected in hypertensive patients.
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The patients were invited to take part in the sample when they attended the service for routine care. The exclusion criteria were age <18 years, pregnancy and puerperal period, preliminary diagnosis of diabetes mellitus, counterindication for BP measuring on the ankles, patients with cardiac arrhythmia, and use of antiplatelet aggregation and anticoagulation drugs. The participants were divided in two groups (normotensive and hypertensive), according to the medical diagnosis obtained from their patient history. The researcher held the interview in a private room and collected the following information: age, skin color, and education. The age was based on the birth date registered on the identity card or on the participant’s information. The skin color was selfreferred and ranked as white or nonwhite. To assess the education, the individual informed the number of years of study. The following anthropometric data were measured: weight, height, body mass index (BMI), and abdominal circumference (AC). The BMI and AC were calculated and ranked according to the cutoff points established by World Health Organization19 and the Brazilian Obesity Guidelines,20 respectively. To measure the BP by means of the indirect oscillometric method, automated portable OMRON equipment was used, Model HEM 705 CP. All technical requirements for appropriate BP collection (resting before taking the BP, proper size and/or placement of cuff, did the patient smoke prior, machines calibrated), followed the specifications of the Brazilian Arterial Hypertension Guidelines (2010).5 The PP was equivalent to the difference between the SBP and diastolic blood pressure in mm Hg on the arm with the highest SBP. The reference values were $50 mm Hg for outpatient measures.21 When the SBP values were identical on both limbs, the right arm was elected. To determine the ABI, the pressure levels were measured on the four limbs during the routine clinical examination, using two AOS, according to the technique described by Kawamura.7 The reference values adopted in this research followed the indications of the Brazilian Arterial Hypertension Guidelines.5 The ABI used for the data analysis was the lowest index obtained on the right and left limbs.22 The delta-BB was obtained by means of the absolute difference in mm Hg between the SBP on the arms measured simultaneously and the delta-ABI by the absolute difference between the ABI on both ankles. The reference values used ranged between 0 and 8 mm Hg for delta-BB and between 0 and 0.13 for delta-ABI.7 The research development complied with the Brazilian and international ethical standards for research involving human beings. Approval was obtained from the Institutional Review Board at the University of S~ao Paulo at Ribeir~ao Preto College of Nursing. All patients agreed to participate in the study and signed the informed consent form. The descriptive analyses, involving the calculation of absolute frequencies and percentages, were developed in the statistical software Statistical Package for Social Science (SPSS, version 15.0). To compare the data between the two groups, Student’s t test for independent samples was used. The linear regression analysis was used to identify the correlation between the variables. The results were expressed as means standard errors of the means, and the differences were considered statistically significant when P < 0.05.
METHODS Quantitative, descriptive, and cross-sectional approach, developed at a preventive health service in a Brazilian city between August 2011 and June 2012.
RESULTS The study participants were 123 individuals, including 54 (43.9%) normotensive and 69 (56.1%) hypertensive patients.
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In the total group, 114 (92.7%) participants were female, equivalent to 53 normotensive (46.5%) and 61 hypertensive (53.5%) individuals. Concerning the skin color, the majority was white (94% or 76.4%), corresponding to 48 (88.9%) normotensive and 46 (66.7%) hypertensive individuals. Both groups showed a similar education level. Most participants possessed less than 8 years of education (56.7% of normotensive and 55.1% of hypertensive individuals). The lowest education level was observed among the hypertensive patients, with significant illiteracy rates, equivalent to 16 (23.2%) participants. Among the normotensive patients, only two (3.7%) individuals were illiterate. The comparative analysis of the mean ages and the data collection during the physical examination is shown in Table 1. For the mean SBP of the right and left arms and ankles, a statistically significant difference (P < 0.0001) was found when comparing the groups. The hypertensive patients showed a significant increase in SBP, BMI, AC, and PP levels when compared with the normotensive individuals. The weight ranking according to the BMI shows that most normotensive patients are overweight, corresponding to 22
TABLE 1 COMPARATIVE ANALYSIS OF MEAN AGE AND DATA COLLECTED THROUGH PHYSICAL EXAMINATION IN NORMOTENSIVE (NT) AND HYPERTENSIVE (HT) INDIVIDUALS. ~ SERTAOZINHO-SP, 2011-2012. Group Variable Age (y) SBP elected arm (mm Hg) SBP right ankle (mm Hg) SBP left ankle (mm Hg) BMI (kg/m2) AC (cm) PP Right ABI Left ABI Lowest ABI Delta BB (mm Hg) Delta ABI
NT 39.74 117.8 136.0 138.1 27.40 88.93 43.91 1.18 1.17 1.15 6.2 0.06
1.84 1.13 1.78 1.49 0.67 1.79 1.08 0.00 0.01 0.01 0.71 0.01
HT 55.62 147.0 160.8 161.2 30.94 100.0 60.59 1.15 1.15 1.10 10.16 0.11
1.66* 2.27* 2.68* 3.27* 0.84y 1.57* 1.89* 0.02 0.02 0.02 1.45 0.01
ABI = ankle-brachial index; AC = abdominal circumference; BB = brachial-brachial; BMI = body mass index; PP = pulse pressure; SBP = systolic blood pressure. Values expressed as mean standard error of the mean; n = 54 normotensive and 69 hypertensive individuals. *P < 0.001 compared with the NT group. y P < 0.05 compared with the NT group.
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(40.7%) participants. Among the hypertensive patients, 21 (30.4%) individuals are also overweight; the analysis of mean BMI in the different samples, however, shows that hypertensive patients have a significantly higher BMI (P < 0.05) when compared with the normotensive individuals. Based on the parameters of the Brazilian Obesity Guidelines20 for the AC measures, 29 (54%) normotensive and 51 (73.9%) hypertensive individuals were classified in the category ‘‘substantially increased risk’’ ($88 for women and $102 for men). In the analysis of this variable, a statistically significant difference was found (P < 0.0001) in the scores attributed to hypertensive patients were compared with the findings in the normotensive group.20 The analysis of the mean PP revealed a statistically significant difference (P < 0.0001) between the hypertensive and normotensive individuals’ levels. Figure 1 shows the distribution of the population according to the PP levels. As regard the ABI, no difference was found in the mean indices between the groups, but alterations were found in 20 (29%) hypertensive participants, being 12 (60%) female and eight (40%) male individuals. In this group, one (5%) participant showed mild obstruction, four (20%) had indices compatible with moderate obstruction, and 15 (75%) possible calcification, as indicated by ABI >1.3. Indices #0.9 were detected in five (7.2%) participants, with one (20%) alteration on the right ankle, one (20%) on the left ankle, and three (60%) on both limbs. Figure 2 shows the population distribution according to the ABI classification, in line with the Brazilian Arterial Hypertension Guidelines.5 The analysis of the correlation between ABI and PP is displayed in Figures 3 and 4. The absence of correlation between the ABI and PP of normotensive individuals is observed (Pearson’s coefficient = 0.24, P < 0.18, r2 = 0.06), as well as a statistically significant correlation between the ABI and PP levels of hypertensive individuals (Pearson’s coefficient = 0.45, P < 0.0001, r2 = 0.21).
DISCUSSION The results appointed that the sample used was predominantly female. The low health service usage rates in the male sex, especially prevention services, can be attributed to the fact that self-care in health is attributed to women.23,24 Concerning the skin color, most participants indicated they were white. This information can represent a bias, as the classification completely depended on how the participants designated themselves. Despite these results, the miscegenation of the Brazilian population makes ethnical classification difficult, often leading to generic denominations.25 In both groups, the mean education was less than 8 years of study. The lowest level was observed among the hypertensive individuals, with a significant illiteracy percentage. Similar results were found in Brazilian and foreign studies, appointing the association between the low education level and the frequent occurrence of cardiovascular morbidity and mortality events.26,27 As regard the participants’ age range, the prevalence of younger individuals in the normotensive group can be justified by the physiological alterations over time and by the higher
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Figure 1. Distribution of population, classified as normotensive and hypertensive, according to pulse pressure (PP) levels. Sert~ aozinho, 20112012.
incidence of pathologic events directly associated with advancing age.21,28,29 Another finding in this research was the high frequency of overweight participants, confirming an increasing global trend and public health problem.8,30 The relevant anthropometric alterations found are highlighted, mainly among the hypertensive individuals. In this research, the mean BP in the hypertensive group was significantly higher, although most participants in that group affirmed the regular use of antihypertensive drugs. High pressure levels contribute considerably to the atherogenic process, consequently leading to ABI alterations. R oldan et al,31 observed a significant increase in the ABI among the patients who kept their BP under control, showing the influence of blood pressure on the ABI levels.31 Similarly, Albuquerque et al32 developed a study in which hypertensive patients with altered and normal ABI were compared, showing significant differences between the groups in the variables BMI alterations and left ventricular hypertrophy, highlighting the importance of structural assessments in patients with that clinical profile.
Although our findings did not reveal significant differences in the mean ABI between the groups, alterations compatible with PAD, suggested by ABI <0.9, were found among middle-aged and elderly adult hypertensive individuals only, for the right and the left ABI. These individuals had their ABI classified as mild (ABI = 0.71–0.90) and moderate (ABI = 0.41–0.70) obstruction, the latter of which stood out. Various studies prove this relation identified in our study. In this age range, a low ABI is associated with increased mortality and high risk of coronary artery disease and cerebrovascular diseases.33,34 Similarly, McDermottet al35 also identified that individuals with ABI <0.9 experience considerable and progressive reductions in lower limb functioning and mobility, including disability for continuing walks. None of the research participants indicated any symptoms, but there is evidence that ABI is associated with the greater severity of lower-extremity occlusive PAD in asymptomatic individuals.36,37 During 1 year, researchers monitored individuals who were hospitalized and concluded that symptomatic PAD
Figure 2. Distribution of population, classified as normotensive (NT) and hypertensive (HT), according to ankle-brachial index (ABI). Sert~aozinho, 2011-2012.
Figure 3. Correlation between ankle-brachial index (ABI) and pulse pressure (PP) in normotensive individuals. Pearson’s coefficient = 0.11, P = 0.44, r2 = 0.01.
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Figure 4. Correlation between ankle-brachial index (ABI) and pulse pressure (PP) in hypertensive individuals. Pearson’s coefficient = 0.45, P < 0.0001, r2 = 0.21.
patients corresponded to only 8% of the sample, whereas ABI changes were found in 37% of the patients (29% ABI inferior and 8% superior to normal indices); the authors concluded that assessing the ABI contributes to the identification of asymptomatic PAD patients.38 ABI levels >1.3 were also identified, with statistical significance, in the hypertensive group. According to the risk ranking proposed by Resnick,39 ABI >1.3 is a strong predictor of mortality due to CVD, as it is associated with arterial incompressibility due to the calcification of the mean layer of the arteries. This condition is common among individuals with arterial and renal conditions and can be related to advanced age. These findings evidence that hypertensive individuals are at risk of developing or suggest the existence of some established CVD. A presumable bias in this research is the finding that, if ABI indices superior to 1.3 are associated with the incompressibility of the vascular wall, the arteries may have become incompressible during the insufflation of the cuff, as identified in the study by Kawamura.7 This phenomenon is more frequent in groups at high cardiovascular risk, such as the elderly.40 This possibility can interfere in the detection of the ABI levels, modifying their clinical meaning. Therefore, many researchers eliminate participants with increased ABI from their research, but the choice to maintain this sample in our study is due to the importance of detecting the risk associated with diffuse atherosclerotic vessel disease, manifested by a high ABI. The calculation of the delta-BB and delta-ABI indices showed important changes in the delta-BB among the hypertensive individuals. Until date, after the pioneer proposal by Kawamura,7 the deltas were assessed in only one study developed in Brazil, finding results similar to this research.41 The importance and need for further research is highlighted, using these different cardiovascular risk assessment methods with a view to exploring their effectiveness and possible clinical applicability. The research findings indicate that hypertensive individuals showed the highest PP. Evidence appoints the existence of increased risk in patients with augmented hypertension and PP.42,43 Benetos et al44 found that PP and cardiovascular mortality are associated in hypertensive patients, with a higher mortal-
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ity in patients with a higher PP. In a clinical review, it was observed that PP levels superior to 60–80 mm Hg revealed pathologic phenomena, mainly arteriosclerosis, with a high prevalence in the elderly population.45 Alterations in the PP, especially when augmented, can suggest the exacerbation of the cardiovascular risk among hypertensive patients who use medication therapy, type II diabetes patients, kidney failure patients, and subjects with generalized atherosclerotic disease.6 In the Brazilian population, a study was developed to investigate the correlation among ABI, BP, PP, and functional capacity among hypertensive and normotensive individuals. The study found higher SBP and PP levels, besides a lower functional capacity associated with ABI alterations among hypertensive patients. The results obtained showed that the correlation among all these factors influences the severity and increases the prevalence of secondary events like lower-extremity occlusive PAD.46 The physiopathologic mechanisms underlying the involvement of hypertension as a factor that contributes to the development of vascular illnesses are complex. Various studies indicate that both the hardening of the arteries and the thickening of the inner middle layer have indicated an association with increased morbidity and mortality.47,48 When the PP and ABI are correlated among the study groups, a statistically significant correlation is observed among the hypertensive patients. As described in the literature, the hardening of the vessels is accelerated in the presence of hypertension, with consequent alterations in the mechanical properties of the arterial wall.49 In addition, this finding can be explained by the increased hardening of the arteries associated with advanced age, a predictable physiological condition of aging.21 Risk factors like age, sex, hypertension, and obesity significantly contribute to the development of peripheral and coronary atherosclerosis.50 In this study, the appointed factors were observed in the hypertensive patients, including a relevant manifestation of alterations in the clinical cardiovascular risk markers assessed. The correlations and associations observed in this study confirm the current evidence that ABI and PP alterations are correlated with hypertension. In short, the use of the proposed cardiovascular risk predictors shows that the hypertensive individuals manifested more frequent alterations when compared with the normotensive persons.
CLINICAL IMPLICATIONS The clinical relevance of using cardiovascular risk stratification parameters is appointed, permitting the identification and early forwarding of risk patients and the prevention of arterial complications. It is highlighted that the use of the measuring instruments applied can contribute to nursing practice, increasing the population’s chances of access and appropriate forwarding for diagnosis and treatment.
ACKNOWLEDGMENTS No conflicts of interest to declare. A.N.T. received an Institutional Scientific Initiation Grant (PIBIC) from the University of S~ao Paulo Pro-Rectory of Research. For the remaining authors none were declared.
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Use of noninvasive procedures in the cardiovascular risk assessment of hypertensive and normotensive individuals Adrielle Naiara Toneti, RN, Dayana Freitas, RN, Patrıcia Magnabosco, PhD, Bruna Francielle Toneti, Student, Daniel Martinez Lana, PE, Simone de Godoy, PhD, and Leila Maria Marchi-Alves, PhD
Background: Arterial hypertension is associated with a high prevalence of vascular alterations. The use of noninvasive procedures to assess peripheral arterial diseases in the ranking of cardiovascular risks has been increasingly valued in clinical practice and should be adopted in nursing. Objective: To identify the cardiovascular risk of hypertensive and normotensive individuals through the use of different noninvasive procedures to assess the vascular function and integrity: ankle-brachial index, pulse pressure, and delta brachial-brachial and delta ankle-brachial indexes. Methods: Quantitative, descriptive, and cross-sectional study undertaken at a health service in a Brazilian city. The research variables were age, sex, blood pressure, abdominal circumference, body mass index, ankle-brachial index, pulse pressure, and delta brachial-brachial and delta ankle-brachial indexes. Results: Fifty-four (43.1%) normotensive and 69 (56.9%) hypertensive individuals participated in the study. Alterations were identified in ankle-brachial index, corresponding to mild and moderate arterial obstruction, among hypertensive individuals only (7.2%), with higher pulse pressure indices (P < 0.0001). The assessment of the correlation between the ankle-brachial index and pulse pressure showed no correlation in the normotensive group and a statistically significant correlation among hypertensive patients (Pearson’s coefficient = 0.45, P < 0.0001, r2 = 0.21). A statistically significant difference (P < 0.05) was found in the analysis of the mean delta brachial-brachial (6.2 0.71 mm Hg for normotensive and 10.16 1.45 mm Hg for hypertensive individuals) and delta ankle-brachial index (0.06 0.01 for normotensive and 0.11 0.01 for hypertensive individuals). Conclusions: The use of the proposed cardiovascular risk predictors shows more frequent alterations among hypertensive than normotensive individuals. (J Vasc Nurs 2016;34:17-23)
In the last two centuries, as a result of the changes derived from the epidemiologic and demographic transition processes, nontransmissible chronic diseases and their complications have become increasingly frequent, including cardiovascular diseases (CVDs),1 which represent the main cause of death all over the world and represent about 30% of global deaths and 20% of all deaths in individuals aged older than 30 years in Brazil.2,3 Hypertension is one of the main CVDs and is also considered a relevant risk factor for the occurrence of other morbid events. The From the University of S~ao Paulo at Ribeir~ao Preto College of Nursing, Ribeir~ao Preto, SP, Brazil; Federal University of Uberl^andia, Uberl^andia, MG, Brazil; General and Specialized Nursing Department, University of S~ao Paulo at Ribeir~ao Preto College of Nursing, Ribeir~ao Preto, SP, Brazil. Corresponding author: Leila Maria Marchi-Alves, PhD, General and Specialized Nursing Department, University of S~ao Paulo at Ribeir~ao Preto College of Nursing, Av. dos Bandeirantes, 3900, Bairro Monte Alegre, CEP: 14.040-902, Ribeir~ao Preto, SP, Brazil (E-mail: [email protected]). 1062-0303/$36.00 Copyright Ó 2016 by the Society for Vascular Nursing, Inc. http://dx.doi.org/10.1016/j.jvn.2015.10.001
boundary that defines hypertension considers systolic blood pressure (SBP) $140 mm Hg and⁄or diastolic blood pressure $90 mm Hg when measured in the doctor’s office. It is estimated that 1.56 billion adults will be living with hypertension in 2025, which is why the disease is qualified as an increasing and global public health problem.4 In Brazil, the prevalence of hypertension ranges between 22.3% and 43.9% of the population.5 Recently, many studies have appointed the effective use of noninvasive procedures for the clinical assessment of cardiovascular risk, including the measuring of the ankle-brachial index (ABI) and the determination of the pulse pressure (PP).6-8 The ABI is a noninvasive measure to detect blood pressure changes in the lower limbs, being a simple and cost-effective method.9 In Brazil, measuring the ABI is indicated for individuals aged $70 years or individuals aged between 50 and 69 years with clinical characteristics and risk factors specified in the Brazilian Hypertension Guidelines (2010).5 According to the Brazilian guidelines, the ABI is considered normal when superior to 0.90; lower levels indicate arterial obstruction.5 Despite these recommendations, this method has not been applied in daily clinical practice, which can be justified by the need to use specific equipment and training.10 The American Heart Association encourages the exploration of more feasible alternative methods for routine ABI assessment in clinical practice, with a view to reducing the application costs
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and enhancing its implementation in primary health care.11 From that perspective, studies have demonstrated the efficacy of using automated oscillatory sphygmomanometers (AOS) to determine the ABI,7,10 which for many years was restricted to the use of the vascular Doppler only. More recently, nurses have been developing research, demonstrating satisfactory results when this resource is used.10,12,13 Arevalo-Manso et al10 observed that the sensitivity and specificity of an automatic blood pressure device detecting ABI <0.90 shows acceptable levels when nurses perform the technique. Nelson et al12 determined the level of agreement between a conventional ABI measurement (using Doppler and mercury sphygmomanometer taken by a research nurse) and ABI measure (using an oscillometric device taken by a practice nurse). They concluded that the ABI measure using automated equipment may be used as a screening tool for high risk and CVDs of patients in primary care. Romero-Vilaplana et al13 showed that the assessment of ABI should be part of the exploration of chronic patients who come periodically to nursing consultations, particularly those ones with a moderate or high cardiovascular risk. To look for alternatives applicable to the clinical routine of cardiovascular risk assessment, Kawamura,7 departing from the premise that the similarity between the sides of the human body should assume highly similar pressure levels, except in case of anatomic–pathologic abnormalities, elaborated two new risk assessment forms, obtained when the blood pressure and ABI are measured: the delta brachial-brachial index (delta-BB) and the delta ankle-brachial index (delta-ABI). These innovative assessment forms, when altered (>8 mm Hg for delta-BB and >0.13 for delta-ABI), showed very high prevalence levels in patients having peripheral arterial disease (PAD), constituting an interesting complementary cardiovascular risk assessment method that can be further explored in future studies. Besides the use of the clinical indicators mentioned, the PP should also be highlighted, being a useful predictor of coronary artery disease or total CVD, mainly in middle-aged or elderly people.14,15 Investigators also suggest PP as a marker of preclinical CVD.16 The use of noninvasive procedures to assess atherosclerosis in the cardiovascular risk ranking has been increasingly valued, especially the use of ABI.17 In the literature, recommendations are found for research that combines the use of different noninvasive procedures to assess the vascular function and integrity, as the different measuring methods reflect the distinct stages of the vascular alteration process that leads to cardiovascular events.18 Based on the importance and increasing use of these clinical indicators to identify cardiovascular risks, the objective in this study was to identify the cardiovascular risk in hypertensive and normotensive individuals through the determination of the ABI, PP, and delta-BB and the delta-ABI, using AOS. Altered levels of the research variables are expected in hypertensive patients.
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The patients were invited to take part in the sample when they attended the service for routine care. The exclusion criteria were age <18 years, pregnancy and puerperal period, preliminary diagnosis of diabetes mellitus, counterindication for BP measuring on the ankles, patients with cardiac arrhythmia, and use of antiplatelet aggregation and anticoagulation drugs. The participants were divided in two groups (normotensive and hypertensive), according to the medical diagnosis obtained from their patient history. The researcher held the interview in a private room and collected the following information: age, skin color, and education. The age was based on the birth date registered on the identity card or on the participant’s information. The skin color was selfreferred and ranked as white or nonwhite. To assess the education, the individual informed the number of years of study. The following anthropometric data were measured: weight, height, body mass index (BMI), and abdominal circumference (AC). The BMI and AC were calculated and ranked according to the cutoff points established by World Health Organization19 and the Brazilian Obesity Guidelines,20 respectively. To measure the BP by means of the indirect oscillometric method, automated portable OMRON equipment was used, Model HEM 705 CP. All technical requirements for appropriate BP collection (resting before taking the BP, proper size and/or placement of cuff, did the patient smoke prior, machines calibrated), followed the specifications of the Brazilian Arterial Hypertension Guidelines (2010).5 The PP was equivalent to the difference between the SBP and diastolic blood pressure in mm Hg on the arm with the highest SBP. The reference values were $50 mm Hg for outpatient measures.21 When the SBP values were identical on both limbs, the right arm was elected. To determine the ABI, the pressure levels were measured on the four limbs during the routine clinical examination, using two AOS, according to the technique described by Kawamura.7 The reference values adopted in this research followed the indications of the Brazilian Arterial Hypertension Guidelines.5 The ABI used for the data analysis was the lowest index obtained on the right and left limbs.22 The delta-BB was obtained by means of the absolute difference in mm Hg between the SBP on the arms measured simultaneously and the delta-ABI by the absolute difference between the ABI on both ankles. The reference values used ranged between 0 and 8 mm Hg for delta-BB and between 0 and 0.13 for delta-ABI.7 The research development complied with the Brazilian and international ethical standards for research involving human beings. Approval was obtained from the Institutional Review Board at the University of S~ao Paulo at Ribeir~ao Preto College of Nursing. All patients agreed to participate in the study and signed the informed consent form. The descriptive analyses, involving the calculation of absolute frequencies and percentages, were developed in the statistical software Statistical Package for Social Science (SPSS, version 15.0). To compare the data between the two groups, Student’s t test for independent samples was used. The linear regression analysis was used to identify the correlation between the variables. The results were expressed as means standard errors of the means, and the differences were considered statistically significant when P < 0.05.
METHODS Quantitative, descriptive, and cross-sectional approach, developed at a preventive health service in a Brazilian city between August 2011 and June 2012.
RESULTS The study participants were 123 individuals, including 54 (43.9%) normotensive and 69 (56.1%) hypertensive patients.
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In the total group, 114 (92.7%) participants were female, equivalent to 53 normotensive (46.5%) and 61 hypertensive (53.5%) individuals. Concerning the skin color, the majority was white (94% or 76.4%), corresponding to 48 (88.9%) normotensive and 46 (66.7%) hypertensive individuals. Both groups showed a similar education level. Most participants possessed less than 8 years of education (56.7% of normotensive and 55.1% of hypertensive individuals). The lowest education level was observed among the hypertensive patients, with significant illiteracy rates, equivalent to 16 (23.2%) participants. Among the normotensive patients, only two (3.7%) individuals were illiterate. The comparative analysis of the mean ages and the data collection during the physical examination is shown in Table 1. For the mean SBP of the right and left arms and ankles, a statistically significant difference (P < 0.0001) was found when comparing the groups. The hypertensive patients showed a significant increase in SBP, BMI, AC, and PP levels when compared with the normotensive individuals. The weight ranking according to the BMI shows that most normotensive patients are overweight, corresponding to 22
TABLE 1 COMPARATIVE ANALYSIS OF MEAN AGE AND DATA COLLECTED THROUGH PHYSICAL EXAMINATION IN NORMOTENSIVE (NT) AND HYPERTENSIVE (HT) INDIVIDUALS. ~ SERTAOZINHO-SP, 2011-2012. Group Variable Age (y) SBP elected arm (mm Hg) SBP right ankle (mm Hg) SBP left ankle (mm Hg) BMI (kg/m2) AC (cm) PP Right ABI Left ABI Lowest ABI Delta BB (mm Hg) Delta ABI
NT 39.74 117.8 136.0 138.1 27.40 88.93 43.91 1.18 1.17 1.15 6.2 0.06
1.84 1.13 1.78 1.49 0.67 1.79 1.08 0.00 0.01 0.01 0.71 0.01
HT 55.62 147.0 160.8 161.2 30.94 100.0 60.59 1.15 1.15 1.10 10.16 0.11
1.66* 2.27* 2.68* 3.27* 0.84y 1.57* 1.89* 0.02 0.02 0.02 1.45 0.01
ABI = ankle-brachial index; AC = abdominal circumference; BB = brachial-brachial; BMI = body mass index; PP = pulse pressure; SBP = systolic blood pressure. Values expressed as mean standard error of the mean; n = 54 normotensive and 69 hypertensive individuals. *P < 0.001 compared with the NT group. y P < 0.05 compared with the NT group.
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(40.7%) participants. Among the hypertensive patients, 21 (30.4%) individuals are also overweight; the analysis of mean BMI in the different samples, however, shows that hypertensive patients have a significantly higher BMI (P < 0.05) when compared with the normotensive individuals. Based on the parameters of the Brazilian Obesity Guidelines20 for the AC measures, 29 (54%) normotensive and 51 (73.9%) hypertensive individuals were classified in the category ‘‘substantially increased risk’’ ($88 for women and $102 for men). In the analysis of this variable, a statistically significant difference was found (P < 0.0001) in the scores attributed to hypertensive patients were compared with the findings in the normotensive group.20 The analysis of the mean PP revealed a statistically significant difference (P < 0.0001) between the hypertensive and normotensive individuals’ levels. Figure 1 shows the distribution of the population according to the PP levels. As regard the ABI, no difference was found in the mean indices between the groups, but alterations were found in 20 (29%) hypertensive participants, being 12 (60%) female and eight (40%) male individuals. In this group, one (5%) participant showed mild obstruction, four (20%) had indices compatible with moderate obstruction, and 15 (75%) possible calcification, as indicated by ABI >1.3. Indices #0.9 were detected in five (7.2%) participants, with one (20%) alteration on the right ankle, one (20%) on the left ankle, and three (60%) on both limbs. Figure 2 shows the population distribution according to the ABI classification, in line with the Brazilian Arterial Hypertension Guidelines.5 The analysis of the correlation between ABI and PP is displayed in Figures 3 and 4. The absence of correlation between the ABI and PP of normotensive individuals is observed (Pearson’s coefficient = 0.24, P < 0.18, r2 = 0.06), as well as a statistically significant correlation between the ABI and PP levels of hypertensive individuals (Pearson’s coefficient = 0.45, P < 0.0001, r2 = 0.21).
DISCUSSION The results appointed that the sample used was predominantly female. The low health service usage rates in the male sex, especially prevention services, can be attributed to the fact that self-care in health is attributed to women.23,24 Concerning the skin color, most participants indicated they were white. This information can represent a bias, as the classification completely depended on how the participants designated themselves. Despite these results, the miscegenation of the Brazilian population makes ethnical classification difficult, often leading to generic denominations.25 In both groups, the mean education was less than 8 years of study. The lowest level was observed among the hypertensive individuals, with a significant illiteracy percentage. Similar results were found in Brazilian and foreign studies, appointing the association between the low education level and the frequent occurrence of cardiovascular morbidity and mortality events.26,27 As regard the participants’ age range, the prevalence of younger individuals in the normotensive group can be justified by the physiological alterations over time and by the higher
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Figure 1. Distribution of population, classified as normotensive and hypertensive, according to pulse pressure (PP) levels. Sert~ aozinho, 20112012.
incidence of pathologic events directly associated with advancing age.21,28,29 Another finding in this research was the high frequency of overweight participants, confirming an increasing global trend and public health problem.8,30 The relevant anthropometric alterations found are highlighted, mainly among the hypertensive individuals. In this research, the mean BP in the hypertensive group was significantly higher, although most participants in that group affirmed the regular use of antihypertensive drugs. High pressure levels contribute considerably to the atherogenic process, consequently leading to ABI alterations. R oldan et al,31 observed a significant increase in the ABI among the patients who kept their BP under control, showing the influence of blood pressure on the ABI levels.31 Similarly, Albuquerque et al32 developed a study in which hypertensive patients with altered and normal ABI were compared, showing significant differences between the groups in the variables BMI alterations and left ventricular hypertrophy, highlighting the importance of structural assessments in patients with that clinical profile.
Although our findings did not reveal significant differences in the mean ABI between the groups, alterations compatible with PAD, suggested by ABI <0.9, were found among middle-aged and elderly adult hypertensive individuals only, for the right and the left ABI. These individuals had their ABI classified as mild (ABI = 0.71–0.90) and moderate (ABI = 0.41–0.70) obstruction, the latter of which stood out. Various studies prove this relation identified in our study. In this age range, a low ABI is associated with increased mortality and high risk of coronary artery disease and cerebrovascular diseases.33,34 Similarly, McDermottet al35 also identified that individuals with ABI <0.9 experience considerable and progressive reductions in lower limb functioning and mobility, including disability for continuing walks. None of the research participants indicated any symptoms, but there is evidence that ABI is associated with the greater severity of lower-extremity occlusive PAD in asymptomatic individuals.36,37 During 1 year, researchers monitored individuals who were hospitalized and concluded that symptomatic PAD
Figure 2. Distribution of population, classified as normotensive (NT) and hypertensive (HT), according to ankle-brachial index (ABI). Sert~aozinho, 2011-2012.
Figure 3. Correlation between ankle-brachial index (ABI) and pulse pressure (PP) in normotensive individuals. Pearson’s coefficient = 0.11, P = 0.44, r2 = 0.01.
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Figure 4. Correlation between ankle-brachial index (ABI) and pulse pressure (PP) in hypertensive individuals. Pearson’s coefficient = 0.45, P < 0.0001, r2 = 0.21.
patients corresponded to only 8% of the sample, whereas ABI changes were found in 37% of the patients (29% ABI inferior and 8% superior to normal indices); the authors concluded that assessing the ABI contributes to the identification of asymptomatic PAD patients.38 ABI levels >1.3 were also identified, with statistical significance, in the hypertensive group. According to the risk ranking proposed by Resnick,39 ABI >1.3 is a strong predictor of mortality due to CVD, as it is associated with arterial incompressibility due to the calcification of the mean layer of the arteries. This condition is common among individuals with arterial and renal conditions and can be related to advanced age. These findings evidence that hypertensive individuals are at risk of developing or suggest the existence of some established CVD. A presumable bias in this research is the finding that, if ABI indices superior to 1.3 are associated with the incompressibility of the vascular wall, the arteries may have become incompressible during the insufflation of the cuff, as identified in the study by Kawamura.7 This phenomenon is more frequent in groups at high cardiovascular risk, such as the elderly.40 This possibility can interfere in the detection of the ABI levels, modifying their clinical meaning. Therefore, many researchers eliminate participants with increased ABI from their research, but the choice to maintain this sample in our study is due to the importance of detecting the risk associated with diffuse atherosclerotic vessel disease, manifested by a high ABI. The calculation of the delta-BB and delta-ABI indices showed important changes in the delta-BB among the hypertensive individuals. Until date, after the pioneer proposal by Kawamura,7 the deltas were assessed in only one study developed in Brazil, finding results similar to this research.41 The importance and need for further research is highlighted, using these different cardiovascular risk assessment methods with a view to exploring their effectiveness and possible clinical applicability. The research findings indicate that hypertensive individuals showed the highest PP. Evidence appoints the existence of increased risk in patients with augmented hypertension and PP.42,43 Benetos et al44 found that PP and cardiovascular mortality are associated in hypertensive patients, with a higher mortal-
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ity in patients with a higher PP. In a clinical review, it was observed that PP levels superior to 60–80 mm Hg revealed pathologic phenomena, mainly arteriosclerosis, with a high prevalence in the elderly population.45 Alterations in the PP, especially when augmented, can suggest the exacerbation of the cardiovascular risk among hypertensive patients who use medication therapy, type II diabetes patients, kidney failure patients, and subjects with generalized atherosclerotic disease.6 In the Brazilian population, a study was developed to investigate the correlation among ABI, BP, PP, and functional capacity among hypertensive and normotensive individuals. The study found higher SBP and PP levels, besides a lower functional capacity associated with ABI alterations among hypertensive patients. The results obtained showed that the correlation among all these factors influences the severity and increases the prevalence of secondary events like lower-extremity occlusive PAD.46 The physiopathologic mechanisms underlying the involvement of hypertension as a factor that contributes to the development of vascular illnesses are complex. Various studies indicate that both the hardening of the arteries and the thickening of the inner middle layer have indicated an association with increased morbidity and mortality.47,48 When the PP and ABI are correlated among the study groups, a statistically significant correlation is observed among the hypertensive patients. As described in the literature, the hardening of the vessels is accelerated in the presence of hypertension, with consequent alterations in the mechanical properties of the arterial wall.49 In addition, this finding can be explained by the increased hardening of the arteries associated with advanced age, a predictable physiological condition of aging.21 Risk factors like age, sex, hypertension, and obesity significantly contribute to the development of peripheral and coronary atherosclerosis.50 In this study, the appointed factors were observed in the hypertensive patients, including a relevant manifestation of alterations in the clinical cardiovascular risk markers assessed. The correlations and associations observed in this study confirm the current evidence that ABI and PP alterations are correlated with hypertension. In short, the use of the proposed cardiovascular risk predictors shows that the hypertensive individuals manifested more frequent alterations when compared with the normotensive persons.
CLINICAL IMPLICATIONS The clinical relevance of using cardiovascular risk stratification parameters is appointed, permitting the identification and early forwarding of risk patients and the prevention of arterial complications. It is highlighted that the use of the measuring instruments applied can contribute to nursing practice, increasing the population’s chances of access and appropriate forwarding for diagnosis and treatment.
ACKNOWLEDGMENTS No conflicts of interest to declare. A.N.T. received an Institutional Scientific Initiation Grant (PIBIC) from the University of S~ao Paulo Pro-Rectory of Research. For the remaining authors none were declared.
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