The Patient’s Knowledge about Hypertension: an Analysis Based on Cardiovascular Risk

Background: The patient’s knowledge about hypertension can contribute to the best control of it; however, the influence on such knowledge by the seriousness of the disease is unknown. Objective: Assessing the knowledge of individuals with arterial hypertension about their own disease based on the cardiovascular risk. Methods: Cross-sectional, quali-quantitative study, using semi-structured interview made with 113 individuals with hypertension, followed-up in a Basic Health Unit of Joinville, SC, Brazil. Social and economic, anthropometric, laboratorial data and blood pressure values were considered in each cardiovascular risk group, stratified based on the VI Brazilian Guidelines on Hypertension. Results: The mean age was of 57.8+10.0 years, 64.0% being women. The most advanced age, highest systolic blood pressure and hypertension time, as well as the higher rate of presence of diabetes, dyslipidemia and smoking were more predominant in the group with the highest cardiovascular risk. The knowledge about the risk factors and change in lifestyle was not different between the cardiovascular risk groups. Only the knowledge about the complications related to arterial hypertension was not as extensive in the group with very high cardiovascular risk (p<0.001). Conclusion: The group with the highest cardiovascular risk is the one showing the poorest knowledge about the complications related to hypertension.


Introduction
Arterial hypertension (AH) is one of the non-transmissible chronic diseases highly affecting in Brazil 1 .Approximately 30.0% of the Brazilian adult population has AH, and the prevalence is to be even higher with the increasing aging of the population 2,3 .On the other hand, the estimate is that less than 30.0% of the individuals with AH have control on the values of blood pressure (BP) 2,4 .
Despite some studies saying that the best control of AH is related to the knowledge level the individuals have about the disease 5,6 , not much is known about the knowledge degree being influenced by the cardiovascular risk (CVR) level presented by the individual with AH.
Considering that the AH is asymptomatic in most of the patients, the adherence to pharmacological and nonpharmacological measures is one of the major challenges in the treatment of that disease 7 .The increased knowledge about AH has been related to a better drug adherence 8 , better responses to behavioral intervention programs 9 and improved control of BP 6,10,11 .Moreover, the knowledge about the risk factors for the occurrence of cardiovascular diseases has been related to individuals with a higher education level 12 .Patient's Knowledge about Hypertension Int J Cardiovasc Sci.2015;28(3):181-188 Original Manuscript

ABBREVIATIONS AND ACRONYMS
• AH -arterial hypertension • BHU -Basic Health Unit • BMI -body mass index • BP -blood pressure • CVR -cardiovascular risk The usual CVR stratification made in individuals with AH is intended to assess the risk of clinic complication related to AH and to define therapeutic targets to be aimed at 13 .However, the studies on the impact by the knowledge about the AH over its control have not assessed if the knowledge level is changed based on the CVR presented by the patient 5,10,[14][15][16] .This study intended to assess the knowledge level of the hypertensive patients serviced in a basic health unit (BHU) based on the CVR stratification.

Methods
This is a descriptive, quali-quantitative and transversal study, performed between March and August 2013, in a Basic Health Unit (BHU) of Joinville, SC, Brazil.The population of the study was made of individuals of both genders, older than 18 years and previously diagnosed with hypertension being treated in the BHU.The BHU were the study was made comprises an adult population, older than 20 years, of 15 583 people, according to the local data of the Municipal Department of Health.
During the period of the study, the individuals were included in a consecutive manner, after routine medical appointment, during the six months of inclusion, with a non-probabilistic final sample made of 113 individuals.The end of inclusion of individuals was determined based on the theoretical saturation of data 17 and balance among the number of participants for each group of CVR.There was no refusal from individuals to participate in the study and, considering that all data were properly collected, there was no exclusion of participants.

This study was approved by the Research Ethics
Committee from UNIVILLE under no.13514613.0.0000.5366and all participants signed the Informed Consent Form.
The interview and data collection were performed in a reserved room by one of the researchers.The following data were collected: marital status, years of education, estimated time of AH diagnosis and economic status based on the Brazil Economic Classification Criterion 18 .In addition, data regarding co-morbidities and risk factors related to AH for CVR stratification were collected.
Regarding blood pressure, the average of the two latest measures recorded in the patient's history was considered, as well as the weight and height.The results of the laboratory examinations made up to three months prior to the date of inclusion were registered as well.Considering that the patients were already under drug treatment, which could make the CVR classification based on pressure levels difficult, the number of drugs was adopted for stratification regarding the level of AH.This way, the patients using one, two, three or more anti-hypertensive drugs were ranked, respectively, in AH stage I, II and III based on the VI Brazilian Guidelines on Hypertension 13 .However, when the average blood pressure is ranked higher than the number of anti-hypertensive drugs, the average blood pressure value was the one considered.The global CVR was stratified according to the risk factors or complications related to AH and the BP stage, into: low, medium, high and very high risk.
The knowledge about AH was checked through semistructured interview previously prepared by the researchers.Eight open questions were developed for enabling the patients to express themselves on the subject (Chart 1).The interviews were recorded for subsequent transcription and analysis.

Statistical analysis
Questions 1, 2 and 3 were analyzed by the analysis of the content, and the answers were grouped according to the frequency inside subcategories previously defined for this study, as proposed by Minayo 19 and Bardin 20 .Questions 4, 5, 6, 7 and 8 were analyzed regarding their content and categorized and right or not correct/not known based on the VI Brazilian Guidelines on Hypertension 13 .The individuals belonging to the low and medium CVR group were gathered together due to the lower number of individuals belonging to the low risk group (n=17).
The qualitative variables were expressed in frequencies and percentages, and the quantitative variables, in averages and standard deviations.The chi-square test and the exact Fisher test were used when appropriate for assessing the qualitative variables, and the Kruskal-Wallis test was used for assessing the quantitative variables.Data

Results
Out of the 113 individuals studied, 64.0% were female, with mean age of 57.8+10 years.The white color was predominant (96.5%) and 69.0% were in a stable civil marriage.Table 1 shows the general characteristics of each CVR group.
There was a significant difference among the CVR groups regarding the mean age, average systolic blood pressure and the time of the AH diagnosis.But the presence of diabetes, dyslipidemia and smoking was significantly different among the groups, regarding the complications related to AH and the other risk factors.Despite not having significant difference between the body mass index (BMI) among the CVR groups, the average BMI found was >25 kg/m².
The results of the routine laboratory examinations showed that the average values for glucose, total cholesterol and LDL cholesterol were significantly different among the CVR groups.
In question 1, the valid answers were grouped and quantified in six subcategories: symptoms, cardiovascular events, psychological/emotional alteration, risk factors for AH, circulatory and unspecific factors.In this question, the highest frequency of answer by the individuals with low/medium CVR (27.0%) was related to the subcategory psychological/emotional alteration (anxiety, nervousness, irritation).The frequencies in the other subcategories were: 21.0% for AH risk factors (sedentariness, excessive consumption of salt, old age, bad food habits); 21.0% for circulatory factors (thick/sticky blood, bad circulation of blood, pressure on the heart); 12.5% related to symptoms (heart acceleration, dizziness, headache, hot flash); 12.5% for cardiovascular events (effusion, obstructed heart vein) and 6.0% not specific (taking drug, danger, something not working well).Only 6.0% of the answers related question 1 with the blood pressure values in this CVR group.
In the high CVR group, most of the answers (28.0%) were related to AH risk factors (obesity, bad food habits, salt, age).The frequencies in the other subcategories were: 25.0% for circulatory factors, 19.0% for symptoms, 16.0% for psychological/emotional alteration, 6.0% for cardiovascular events and 6.0% for non-specific.
In the very high CVR group, the most frequent answers were in the cardiovascular event (29.0%), mainly cardiac disease and/or stroke.In this group, the most frequent subcategory -cardiovascular event -was also a prevailing finding, the reason for it to be ranked as very high CVR.Frequencies in the other subcategories in this group were: 24.0% for psychological/emotional alteration, 19 Regarding question 3, in respect to the AH drugs, most of the answers described a positive/confidence feeling as to the beneficial effect of the medication between the CVR groups (78.5% low/medium risk, 84.0% high risk and 78.0%very high risk).However, some negative answers were found suggesting the disbelief in the drugs.
Table 2 shows the questions analyzed based on the VI Brazilian Guidelines on Hypertension 13 .There was no significant difference regarding the knowledge about the risk factors that can cause AH among the CVR groups (question 4), a high percentage of lack of knowledge being perceived in the different groups.
Regarding the complications related to AH, there was an increased knowledge among the individuals from the low/medium CVR compared to those from the very high risk.As to overweight, there is high percentage of knowledge about the subject, but no significant difference was found among the groups.In respect to the AH The correct answers to the questions 4 to 8 (analyzed based on the VI Brazilian Guidelines on Hypertension 13 ) among the individuals with controlled blood pressure (≤140/90 mmHg, 59.0% of the sample) were assessed as well, with no significant difference found (Table 3).

Discussion
This study is believed to be the first in Brazil to assess the association of the knowledge level based on CVR presented among individuals with AH.This study revealed a poor knowledge level about the risk factors related to the occurrence of AH, regardless of the CV risk group.Only the knowledge about the consequences related to the abandonment of the AH treatment was shown as significantly higher among the individuals with the lowest CVR.
Considering the CVR stratification proposed by the VI Brazilian Guidelines on Hypertension 13 the individuals with the highest CVR in this study were older, with great prevalence of smoking, dyslipidemia, diabetes, as well as clinical conditions related to AH.Such characteristics were expected, since AH is a chronic disease whose prevalence increases with the population aging 21 .
Despite an inverse correlation between the education level and the prevalence of chronic diseases, such as diabetes and AH 15,22 , as well as the presence of changeable risk factors 15,22 , the education level was not related to the CVR in the individuals with AH in this study.Accordingly, the economic status has not shown correlation with higher CVR either.Such findings can be related to the homogeneity of those variables (education level and economic status) in the sample studied, once they belonged to an urban area inhabited by low income people.
Although the controlled AH prevails (58.0%,Table 3), the BMI average in all the CVR groups was above the target 13 , which shows that this is an important issue within the changeable risk factors of this sample.
The questions analyzed as to their content (questions 1 to 3) showed that AH is understood in the CVR categories based on the factors that can increase the BP (anxiety and stress, in the low CVR group) or on its consequences (cardiac event, in the high CVR group).
It is interesting to notice that no participant has associated AH to the BP defined values and that there was major association of the AH discovery to the presence of symptoms.Considering that the presence of symptoms is not necessarily related to the BP values in individuals with chronic AH, the difficulty and a greater incentive for the local population to check its blood pressure, even in the absence of symptoms, must be analyzed in the future.Regarding drugs, there was a high rate of positive behavior towards the use of those, despite this study not having assessed the adherence.Studies made with low-income population in the United States have also shown that psychological factors, such as stress and nervousness, could be the reason for AH, but in an intermittent character, understanding AH as a chronic disease 23 .Dressler and Santos 24 , in their analysis about the cultural and social dimensions of AH in Brazil, mention also the model of the stressing and psychological factors in the understanding of the cause of AH in Brazilians.However, this model was perceived in this study to change with the increase of the CVR associated to AH.For the individuals with very high CVR, many already with a clinical condition related to hypertension, the AH consequence (infarction or stroke) was associated as the meaning of AH.
Within the questions with quantitative analysis and compared among the CVR groups, only the knowledge related to the AH complications was significantly different among the groups.The individuals with very high CVR knew less about the complications related to AH.This finding indicates that there may be gaps in the communication between the assistance team and the patient in respect to the information related to the disease of the latter, especially for the patient that has already been through cardiovascular event.Many patients may be remaining without the knowledge required about their disease due to the lack of a welcoming space to make their questions 23 .
The knowledge about the disease presented by the patient of AH has been related to an improved control of the BP levels 6,10,11,15 .The increased level of knowledge about AH has been associated as well to an improved drug adherence to the treatment 8,15 .Despite this study not having assessed the adherence, the presence of controlled BP (≤140/90 mmHg), even in a higher percentage compared to other studies 2,4 , has not shown to be related to an increased level of knowledge about AH in subsequent analysis.
Curiously, the group with the highest CVR had more individuals acknowledging the obesity as a prejudicial factor to the control of BP.This finding suggests that the knowledge is not only the single element required for appeasing a change of habits, regarding obesity, diet control and implementation of regular physical activity.
This study presents some methodological limitations and characteristics to be considered in respect to the external validation of results.In order to have a balanced number of participants in each CVR group, the authors had, before analyzing the answers, to stratify the individuals in the sample based on their CVR.This way, there was no "blindness" of researchers regarding the risk group to which each individual belonged.However, considering that the analysis of the content was limited to the comparison of frequencies in the subcategories without other interferences related to the content of the discourse, the lack of "blindness" is believed not to have compromised the results.
Other factor that can limit the data extrapolation was the employment of the number of anti-hypertensive drugs for classifying the blood pressure stage.It is known that the values for each stage of AH are arbitrary and the classification employed is best used in the patients with no drug treatment.However, in order to estimate the values previous to the start of the drug treatment, the number of drugs was arbitrated for estimating the original blood pressure stage.It is worth to remind that the global stratification of cardiovascular risk is not considering only the blood pressure values, and, in the cases the average blood pressure value indicated a blood pressure stage higher than that of the drug, the first was used.Considering also that the risk groups most sensitive to the blood pressure values, low and medium risk, were grouped, any selection obliquity was possible to be minimized.
In addition, despite the questions made in this study being based on and adapted from other studies 5,[16][17][18] made for assessing the knowledge about AH, since there is no Brazilian questionnaire standardized and validated for such, the questions were not previously tested in other studies.It is acknowledged that the methodology applied in this study has not made a broad exploration of the expectations or ideas the research individuals could expose regarding their disease, since the discourse analysis methodology was applied only in the first three questions.On the other hand, the choice for keeping the application of semi-structured interview and analyzing the answers as correct or not correct allowed an increased reliability of the researchers on the real understanding of AH based on the questions made.This is because the researcher explained the questions when he realized that the interviewee was in doubt, while keeping his impartiality.This way, through that methodology, the risk of answers without a real comprehension by the individual with low education Patient's Knowledge about Hypertension Int J Cardiovasc Sci.2015;28(3):181-188 Original Manuscript level acknowledged was reduced in comparison to the use of closed questionnaires, which is the regular procedure.

Conclusion
The knowledge about risk factors and aspects related to the change in lifestyle is similar among hypertensive individuals with different CVR.Only the knowledge about the complications related to AH was shown to be deficient among the hypertensive individuals with higher CVR.

Potential Conflicts of Interest
This study has no relevant conflicts of interest.

Sources of Funding
This study had no external funding sources.

Academic Association
This study is not associated with any graduate programs.

Original Manuscript Chart 1 Questions for assessment of the knowledge about AH 1
were analyzed using the software SPSS version 19.Patient's Knowledge about Hypertension .What is high blood pressure in your opinion? 2. How did you learn that you had high blood pressure?3. What do you think about the medicines for treating the blood pressure?4. What can cause high blood pressure?5. What can happen if high blood pressure is not treated?6.How can you adapt your food habits for controlling the high blood pressure?7. Do you think that overweight can affect the treatment of blood pressure?8. Do you think that high blood pressure is for lifetime?

Table 1 Characteristics of the population studied, per groups of cardiovascular risk (n=113) Variables Low/Medium risk n=49 High risk n=32 Very high risk n=32 Value p
.0% for circulatory factors, 14.0% for symptoms and 14.0% for AH risk factors.None of the individuals in the high and very high CVR groups related question 1 to blood pressure values.Patient's Knowledge about Hypertension a chi-square test; b Fisher's exact test.; c ANOVA; d Kruskal-Wallis test BMI -body mass index; SBP -systolic blood pressure; DBP -diastolic blood pressure; AH -arterial hypertension; CVD FH -cardiovascular disease family history; CRD -chronic renal disease; PAD -peripheral arterial disease; HDL -high-density lipoprotein; LDL -low-density lipoprotein; eGFR -estimate glomerular filtration rate; SD -standard deviation Patient's Knowledge about Hypertension

Table 2 Frequency of the answers given by the population studied regarding the questions about AH, per cardiovascular risk groups
AH -arterial hypertension; CVR -cardiovascular risk; *Chi-square test Patient's Knowledge about Hypertension

Table 3 Understanding of arterial hypertension according to the groups and with no BP control
*Chi-square test; BP -blood pressure