RELATED FACTORS OF NONADHERENCE TO ANTIHYPERTENSIVE TREATMENT AMONG PATIENTS IN NUR-SULTAN CITY: A PILOT STUDY Текст научной статьи по специальности «Клиническая медицина»

Original article

Related factors of nonadherence to antihypertensive treatment among patients in Nur-Sultan city: A pilot study

Botagoz Salkhayeva

Chief specialist of partnerships and human capital development department of the Center of Management, Republican Center for Health Development, Nur-Sultan, Kazakhstan

Reprint. The material was previously published on the Nazarbayev University website in 2018. URL: https://nur.nu.edu. kz/handle/123456789/3306?show=full

Abstract

Objective. The purpose of this study was to assess the level of nonadherence to hypertension treatment and to identify the associated factors among patients with hypertension.

Methods. This was a cross-sectional study. 48 participants were recruited at the urban polyclinic #8 in Nur- Sultan city for this pilot study. The study participants were patients enrolled to the therapeutics appointment with diagnosis of hypertension. Overall, 48 patients consented to participate and filled out the self-administered questionnaires. The survey consisted of five sections, including questions on socio-demographic characteristics, health lifestyles, dietary habits, antihypertensive drug adherence, and perceptions of severity and susceptibility to hypertension, perception of barriers and benefits of hypertension treatment. Descriptive, bivariate and multivariate logistic regression analyses were conducted in Stata 12.

Results. The prevalence of poor adherence among study population was 43.75%. Less duration of hypertension (p=0.088) and shorter length of treatment (0.005) were associated with poor adherence, as well as the higher quantity of antihypertensive medications (p=0.011) and higher frequency of its intake (p=0.046). According to the HBM, low perception of severity of the disease (0.043), low self-efficacy to comply with antihypertensive treatment (0.105) and high perceived barriers (p=0.006) were also associated with poor adherence to antihypertension treatment.

Conclusion. The findings of this pilot study need to be further explored in a study with a bigger sample size. The factors identified according to HBM model can serve as a baseline data for further development and evaluation of programs aimed to improve the adherence to antihypertension treatment.

Key words: nonadherence, hypertension, risk factors, antihypertensive therapy.

Нур-Султан каласында наукастар тарапынан антигипертензиялык емдi кабылдау тэрлбш сактамау факторлары: Пилоттык зерттеу

Салхаева Б.Д.

Менеджмент орталыгыныц Серiктестiк ынтымацтастыц жэне адами капиталды дамыту бeлiмiнiц бас маманы, Денсаулыц сацтауды дамыту республикалыц орталыгы, Нур-Султан, ^азацстан

Тушндеме

Мацсаты. Бул зерттеуд/'ц мацсаты артериялыц гипертензияны емдеуге бей/'мдт/'к децгейiн багалау жэне Нур-султан цаласыныц науцастары арасында цосалцы факторларды аныцтау болып табылады.

Эд/'стер/'. Зерттеу дизайны - айцас зерттеу. Пилоттыц зерттеу Yшiн Нур-султан цаласыныц №8 цалалыцемханасында 48пациентiiрiктелдi. Зерттеуге цатысушылар артериялыцгипертензия диагнозымен терапевт цабылдауына жазылган пациенттер болды. Жалпы, 48 пациент цатысуга кел/'ст/' жэне ез бетiнше сауалнамаларды толтырды. Сауалнама элеуметт/'к-демографиялыц сипаттамалар, eмiр салты, тамацтану, антигипертензияга царсы препараттарга бейiмдiлiк, артериялыц гипертензияга ауырлыц пен бе^мд^т цабылдау, артериялыц гипертензияны емдеуд/'ц кедергiлерi мен артыцшылыцтарын цабылдау туралы мэселелерд/' цамтитын бес бeлiмнен турды. Сипаттама, ею eлшемдi жэне кеп eлшемдi логистикалыц регрессиялыц талдау Stata 12-де жYргiзiлдi.

Нэтижелерi. Зерттелетiн халыцтыц арасында бей/'мдт/'кт/'ц тeмен таралуы 43,75% цурады. Гипертензияны диагнозын цойылганыныц аз узацтыгы (Р=0,088) жэне емдеу цабылдаудыц аз узацтыгы (0,005),

сондай-а; б'рнеше антигипертензиялы; препараттарды ;абылдау (Р=0,011) жэне олардын дэр'н'! ;абылдаудын жогары жилгi (Р=0,046) темен бешмдткпен байланысты болды. Мiнез-кyлыктык; денсаулы; моделiнiн деректерi бойынша аурудын ауырлыгын темен ;абылдау (0,043), антигипертензиялык емдеудi са;тау Yшiн езн-ез тиiмдiлiктiн темендiгi (0,105) жэне ем алу Yшiн жогары ;абылданатын кедерглер (Р=0,006), сондай-а; антигипертензиялык емдеуге бей/'мдт/'кпен байланысты болды.

Цорытынды: Осы пилотты; зерттеуд/'н нэтижелерi Yлкен нау;ас санымен зерттеудi одан эрi талап етедi. Мiнез-к;^лык;тык; денсаулы; моделiне сэйкес аныцталган факторлар антигипертензивтi емдеуге бейiмдiлiктi жа;сартуга багытталган багдарламаларды одан эр1' э^рлеу жэне багалау Yшiн бастап;ы деректер бола алады.

Клттi свздер: беШмдтк, гипертония, ;ау1'п-;атер факторлары, антигипертензивтi ем.

Факторы несоблюдения антигипертензивного лечения среди пациентов в городе

Нур-Султан: пилотное исследование

Салхаева Б.Д.

Главный специалист отдела партнерского сотрудничества и развития человеческого капитала Центра менеджмента, Республиканский центр развития здравоохранения, Нур-Султан, Казахстан

Резюме

Цель. Целью данного исследования является оценка уровня приверженности к лечению артериальной гипертензии и выявление сопутствующих факторов среди пациентов города Нур-Султан.

Методы. Дизайн исследования - перекрестное исследование. Для пилотного исследования были отобраны 48 пациентов Городской поликлиники №8 города Нур-Султан. Участниками исследования были пациенты, записанные на прием к терапевту с диагнозом артериальная гипертензия. В целом, 48 пациентов согласились принять участие и самостоятельно заполнили анкеты. Опрос состоял из пяти разделов, включающих вопросы о социально-демографических характеристиках, образе жизни, питании, приверженности к антигипертензивным препаратам, восприятии тяжести и предрасположенности к артериальной гипертензии, восприятии барьеров и преимуществ лечения артериальной гипертензии. Описательный, двумерный и многомерный логистический регрессионный анализ были проведены в Stata 12.

Результаты. Распространенность низкой приверженности среди исследуемого населения составила 43,75%. Меньшая длительность гипертензии (Р=0,088) и меньшая длительность лечения (0,005), а также прием нескольких антигипертензивных препаратов (Р=0,011) и более высокая частота их приема лекарства (Р=0,046) были связаны с плохой приверженностью. По данным поведенческой модели здоровья, низкое восприятие тяжести заболевания (0,043), низкая самоэффективность для соблюдения антигипертензивного лечения (0,105) и высокие воспринимаемые барьеры для получения лечения (Р=0,006) также были связаны с плохой приверженностью к антигипертензивному лечению.

Выводы. Результаты данного пилотного исследования требуют дальнейшего изучения в исследовании с большим размером выборки. Факторы, выявленные в соответствии с поведенческой моделью здоровья, могут служить исходными данными для дальнейшей разработки и оценки программ, направленных на улучшение приверженности к антигипертензивному лечению.

Ключевые слова: приверженность, гипертония, факторы риска, антигипертензивная терапия.

Corresponding author: Botagoz Salkhayeva, Chief specialist of partnerships and human capital development department of

the Center of Management, Republican Center for Health Development, Nur-Sultan, Kazakhstan

Postal code: 010000

Address: Nur-Sultan, 13 Imanov str.

Phone: + 7 775 819 80 75

E-mail: bsalkhaeva@nu.edu.kz

J Health Dev 2019; 3(32): 69-77 UDC 616.1; 614; 614.2; 614:33 Recieved: 15.08.2019 Accepted: 21.09.2019

This work is licensed under a Creative Commons Attribution 4.0 International License

Introduction

The burden of noncommunicable diseases (NCD) raises large concern and become major public health challenge. The hypertension is a major cause of cardiovascular diseases (CVD) morbidity and mortality rate. Hence, the adherence to antihypertensive pharmacotherapies is a basis of preventing the risks of hypertension and improving population's quality of life.

Nowadays the NCD is the issue of not only developed and rich countries, but it has global pattern and causes growing threat for public health. Hypertension is one of the most significant treatable causes of morbidity and mortality. Currently, the number of deaths due to the consequences of high blood pressure was estimated to be 7.5 million worldwide [1]. According to statistical collection of the Ministry of Health [2] of the Republic of Kazakhstan, the hypertension rate among Kazakhstani people was estimated to be 13391.6 per 100 000 people. In addition, the mortality rate related to the elevated blood pressure ranks on the first place among all deaths [3]. The course of the disease can pass without symptoms during some periods of time, and individuals with high blood pressure may fail to seek the treatment or follow the medical prescriptions, thus leading to the greater risk of complications such as stroke, cardiovascular and renal diseases [4]. This makes adherence to antihypertensive therapy crucial to achieve controlled blood pressure among the population.

Poor adherence to antihypertensive drug therapy is a widespread issue worldwide, accounting for 36.6% to 63.5% [5], with particularly high levels of poor adherence presented in Asian (43.5%) and African countries (63.5%). Very few studies of poor adherence were conducted in Kazakhstan, mainly concentrating on factors such as the presence of heart diseases and comorbidities [6], while behavioral factors influencing to the poor management of antihypertensive therapy were not fully investigated. Recent study in East Kazakhstan show complete non-compliance of 26.9% and partial compliance of 32% to the antihypertensive drug, resulting overall in 58.9% of population failing to manage the prescribed regimen of drug intake. This study investigated the sociodemographic status and clinical characteristics of the patients such as the presence of comorbidities and complications from heart and circulatory system diseases. However, no barriers to the antihypertension treatment adherence were investigated, while according to worldwide experience the barriers largely reflect patient's level of knowledge, control and attitude to medications, making these factors critical for reducing poor adherence.

Barriers to the optimal management of the prescribed medications mostly include dosing frequency, the number of the prescribed

medications, lifestyle factors and satisfaction with medications [7]. Other studies emphasized the importance of the patient's perceptions about the severity, susceptibility, benefits and barriers of hypertension and its treatment, and evaluated their behaviors related to antihypertensive therapy based on the Health Belief Model (HBM) [8].

Poor adherence to hypertension pharmacotherapy is a major cause of mortality due to increased risk of complications. Solely in Kazakhstan, mortality rate related to high blood pressure has a leading position among deaths from other causes and it also ranks on the second place in premature mortality caused by the hypertension within European countries [3]. Numerous researches have demonstrated the significance of antihypertensive therapy on the reduction of mortality and morbidity. However, the determinants of poor adherence to antihypertensive medications have been deeply investigated mostly in western countries [9,10], while in Asian countries there is a lack of such studies.

Study of patients' health beliefs is crucial for systematic assessment of its influence on hypertension management. The Health Belief Model (HBM) is aimed to explain the significance of behavioral constructs related to certain health problems and their interactions with each other, which can be useful in designing effective health behavior interventions. This theoretical framework states that in order to drive behavior people should have intention generated from motivation, while motivation is a result of expectation and magnitude in our case to the treatment consequences. In general, HBM construct include six components including: (1) perceived susceptibility, (2) perceived severity, (3) perceived benefits, (4) perceived barriers, (5) cues to action, and (6) self-efficacy. Few studies have investigated the behavioral determinants of poor adherence with antihypertensive treatment. According to Iranian study, patients with low perceived susceptibility, severity, benefit had poor adherence to antihypertensive treatment [11]. In Chinese population, perceived susceptibility, barriers, cue to action and self-efficacy were associated with hypertension management [12].

In terms of Kazakhstan, there are almost no investigations about nonadherence with validated measures of its prevalence, and no studies on the behavioral patterns that influence the nonadherence. Therefore, the aims of our study were: (1) to identify the prevalence of nonadherence to hypertension treatment among patients with hypertension in Nur-Sultan city; and (2) to examine the association of nonadherence to hypertension treatment with patient's socio-demographic characteristics, self-perceived health status, health lifestyle factors, and perceived susceptibility, severity, benefits and

barriers of hypertension and its treatment using the Health Belief Model (HBM).

Thus, this study's finding will provide

Methods Study population

This pilot study had cross sectional study design and was conducted in the City Policlinic #8 in Nur-Sultan. The study participants were patients enrolled to the therapeutics appointment with diagnosis of hypertension. Overall, 48 patients consented to participate and filled out the survey questionnaires. The Questionnaire consisted of five

Study variables

The outcome variable in this study was the measure of drug adherence as assessed by Hill-Bone compliance scale. Hill-Bone compliance test a validated scale that specifically focuses on hypertensive patients. A Korean study showed a good internal consistency of this scale with Cronbach's alpha =0.80 [15]. The original version of the scale contains 14 questions which are divided to the three domains; and 1) medication taking; 2) appointment keeping; and 3) reduced sodium intake. For our study purposes, we have modified this scale by removing the domain on reduced sodium intake, because the questions from this section were included in the other section of our questionnaire, aimed to assess the dietary habits of participants in more detail. In addition, we omitted 1 more question from the scale on appointment keeping, because it is not relevant to our local primary healthcare system and patients faced difficulties with understanding this question during the pre-test of the questionnaire. Thus, our translated and adopted version of the Hill-Bone scale in Russian and Kazakh languages was comprised of 10 questions, with four-point Likert type response scale, such as "None of the time = 1", "Some of the time = 2", "Most of the time = 3" and "All the time = 4". The cut-off score of the Hill-Bone compliance scale was 16, based on the estimated mean among study participants. Hence, people who scored more than 16 were considered to have poor adherence to antihypertensive drugs, while participants who scored less than or equal to

physicians and health care organizations with valuable information that possibly will generate useful measures to improve clinical outcomes of NCDs related to elevated blood pressure.

sections, including questions on socio-demographic characteristics, health lifestyle and dietary habits, Hill Bone compliance test [13], a scale measuring adherence to antihypertension treatment, and questions based on HBM [14]. The Table 1 illustrates the eligibility criteria for this study.

16, had good adherence to hypertension treatment.

The independent variables for this study included age, gender, marital status, ethnicity, education level, the occupation status, the average monthly income, the perceived health status, smoking status, the time starting the antihypertensive drug intake, the presence of comorbidities, the number of medicines prescribed and the frequency of drug intake, dietary habits, and HBM constructs.

Dietary habits were measured by the scale including 9 questions, cut-off score was 6. Hence, participants who scored more or equal to 6, were considered to have healthy dietary habits.

The five HBM constructs included perceived susceptibility (2 questions) and severity (2 questions) of hypertension, perceived benefits (2 questions), barriers (4 questions) and self-efficacy (3 questions) related to hypertension treatment and management. A Likert-type response scale for these questions ranged from "Totally agree" to "Totally disagree". These scales were dichotomized for the analysis, by combining "Totally agree" and "Agree" in one category ("agree=1), and "Disagree" and "Totally disagree" - in another ("disagree=0). For all HBM components, except to self-efficacy and perceived barriers, the score of "2" was coded as "high perception", while scores "1" or "0" were coded as "low perception" (with one reversed scored item for perceived susceptibility). For the perceived self-efficacy a score of "3" was coded as "high self-

Table 1 - Inclusion and exclusion criteria

Inclusion criteria:

- patients diagnosed with hypertension for at least one year

- the prescription of drug therapy

- availability of informed consent of the patient to participate in the study

Exclusion criteria:

- age younger than 25 years and over 80 years;

- the presence of acute conditions such as myocardial infarction (MI), stroke, acute renal failure (ARF)

- the presence of a mental pathology that prevents a complete examination;

efficacy" and scores less than 3 were coded as "low self-efficacy". For perceived barriers, a score more than or equal to 3 was coded as "high perceived

Ethical considerations

The study was approved by the Nazarbayev University School of Medicine Research Ethics Committee (NUSOM REC). Potential participants were recruited among patients enrolled to the therapeutics appointment. Interviewer approached consecutive participants in a queue to doctor

Statistical analysis

The Stata version 12.0 was used for statistical analysis. Descriptive analysis was performed, with percentages for categorical variables and means with standard deviations (SD) for continuous variables. Chi-squared test was used bivariate analysis of the

Results

Socio-demographic characteristics

The mean age of subjects was 61 years with the range from 39 to 80 years. More than a half of

Bivariate analysis

The mean score of Hill bone compliance test was 16.44, ranging from 10 to 40. 43.75% of patients obtained scores higher than 16 and were classified as "poorly adherent" patients. The total number of patients with good adherence was 27 (56.25%).

According to the Table 3, some patient characteristics were significantly different in these two groups of patients with good and poor adherence. Patients with poor adherence to hypertension treatment were more likely to have less duration of

barriers", and score less than 3 was coded as "low perceived barriers".

appointment, described the study purpose and procedures, and took the oral consent. The oral consent was chosen because it mostly favors the interests of participants by collecting data anonymously and not forcing them to reveal any of the personal identifiable information.

associations between independent variables and poor adherence to antihypertensive drug. Logistic regression was performed for multivariate analysis. The statistical significance level was set at p-value < 0.1.

the sample were female, and the majority were of Kazakh ethnicity (Table 2).

hypertension (p=0.088) and treatment (p=0.005); to have 2 or more drugs per day (p=0.011), and more frequent intake of medications per day (p=0.046); to have less healthy dietary habits (p=0.001), and low perceived severity (p=0.043), high perceived barriers (-=0.006), and low self-efficacy in regard to ability to comply with antihypertension medications, regular doctor appointments and recommendations on salt reduction, compared to patients with good adherence (p=0.105).

Table 2 - Socio-demographic characteristics of the study subjects (n=48)

Demographics n (%)

Age

Mean age (SD) 61 (9.66)

- >55 years old 11 (22.92)

- 56-70 years old 28 (58.33)

- >70 years old 9 (18.75)

Gender

- Male 15(31.25)

- Female 43(68.75)

Marital status

- Married 37(77.08)

- Not married (widowed, divorced) 11(22.91)

Ethnicity

- Kazakh 39 (81.25)

- Others 9 (18.75)

Education level

- High school 4 (8.33)

- College 18(37.5)

- Bachelor degree 25(52.09)

- Post graduate 1 (2.08)

Income level

- >100 000 tg 18 (37.50)

- <100 000 tg 30 (62.50)

Table 3 - Patients' characteristics by adherence to antihypertension medication

Variables Good adherence (n=27) n (%) Poor adherence (n=21) n (%) p - value

Sex

- Male 9 (33.33) 6 (28.57)

- Female 18 (66.67) 15 (71.43) 0.724

Health status

- Poor 3 (11.11) 4 (19.05)

- Satisfactory 14 (51.85) 10 (47.62)

- Good 10 (37.04) 7 (33.33) 0.741

Hypertension diagnosis (years)

- 1-5 7 (25.93) 12 (57.14)

- 6-10 12 (44.44) 5 (23.81)

- 11-15 8 (29.63) 4 (19.05) 0.088*

Other chronic diseases

- No 23 (85.19) 18 (85.71)

- Yes 4 (14.81) 3 (14.29) 0.959

The length of treatment

-<5 years 8 (29.63) 16 (76.19)

-6-15 years 14 (51.85) 3 (14.29)

->16 years 5 (18.52) 2 (9.52) 0.005*

Quantity of medications

- 1 5 (18.52) 12 (57.14)

- 2 15 (55.56) 4 (19.05)

- 3 7 (25.93) 5 (23.81) 0.011*

Frequency of medications

- Once a day 9 (33.33) 15 (71.43)

- Twice a day 16 (59.26) 6 (28.57)

- Three times or more 2 (7.41) 0 0 0.046*

Income (tenge)

- Low 18 (66.67) 12 (57.14)

- High 9 (33.33) 9 (42.86) 0.499

Employment

- Yes 9 (33.33) 10 (47.62)

- No 18 (66.67) 11 (52.38) 0.315

Ethnicity

- Kazakh 20 (74.07) 19 (90.48)

- Other 7 (25.93) 2 (9.52) 0.149

Education

- High school 15 (44.44) 7 (33.33)

- Bachelor degree 12 (55.56) 14 (66.67) 0.125

Age

- >55 5 (18.52) 6 (28.57)

- 55-70 15 (55.56) 13 (61.90)

- >70 7 (25.93) 2 (9.52) 0.317

Diet Score

- High 4 (14.81) 13 (61.90)

- Low 23 (85.19) 8 (38.10) 0.001*

Smoking

- No 25 (92.59) 18 (85.1)

- Yes 2 (7.41) 3 (14.29) 0.439

Marital Status

- Married 20 (74.07) 17 (19.05)

- Not married 7 (25.93) 4 (80.95) 0.574

Perceived susceptibility

- High 12 (44.44) 5 (23.81)

- Low 15 (55.56) 16 (76.19) 0.289

Perceived Severity

- High 27 (100) 18 (85.71)

- Low 0 3 (14.29) 0.043*

Perceived Benefits

- High 8 (29.63) 7 (33.33)

- Low 19 (70.37) 14 (66.67) 0.401

Perceived Barriers

- High 2 (7.40) 8 (14.29)

- Low 25 (92.6) 13 (85.71) 0.006*

Self-Efficacy

- High 23 (85.18) 13 (61.9)

- Low 4 (14.82) 8 (38.1) 0.105*

Multivariate analysis

Table 4 - Results of the multivariate analysis

Variables Adjusted OR CI 95% P-value

Perceived Barriers

- High ref

- Low 0.14 (0.015;1.29) 0.083

Self-efficacy

- High ref

- Low 2.71 (0.27; 27.27) 0.395

Duration of Hypertension

- < 5 years ref

- 5-15 years 5.24 (0.75; 36.70) 0.095

- >15 years 4.53 (0.38; 53.77) 0.231

Medications Quantity

- 1 ref

- 2 7.45 (0.79; 70.28) 0.079

- 3 or more 1.14 (0.12; 10.13) 0.903

Discussion

The purpose of this study was to determine the level of nonadherence to hypertension treatment in patients attending the city polyclinic, and to find out the factors associated with poor adherence using self-administered questionnaire. Less than half of the sample was nonadherent to antihypertensive treatment in our study (43.75%), which is consistent with the range that was indicated for Asian countries [5], but is higher, compared to the prevalence of complete non-adherence as reported by the study that has been conducted in East Kazakhstan (26.9%) [6]. The difference in the non-adherence level with Kazakhstani study could be explained by the differences in methods used for assessing the adherence rates. In our study we used the scale that has been validated in several countries such as Korea, Persia, Malaya and etc., while the study by Mussina and Tuleutayeva [6] was based on self-reported single-item questions, not tested for validity and reliability properties. On the other hand, there could be other factors influencing to the differences observed in adherence level, such as differences in the population characteristics, quality of medical services, population awareness and perceptions about hypertension and its treatment, health behaviors and social support [16].

A plenty of studies were carried out to determine the factors associated with poor adherence to antihypertensive medications and treatment. Majority of the studies have reported that the age, sex, the presence of comorbidities with hypertension, the number of antihypertensive drugs and socioeconomic status were mostly associated with antihypertensive mediations adherence [5,14]. Similar results were reported by the East Kazakhstani study where the age, sex and comorbidities or disability were associated with poor adherence to hypertension treatment [6]. In our study, we did not find statistically significant association of the

poor adherence with any of the socio-demographic factors. However, the association between sociodemographic factors and poor adherence is complex, and may differ due to the population type and cultural variations. Moreover, given the small sample size of our pilot study these results need to be further explored and refined.

However, other factors in our study, including the disease duration, the length of antihypertensive treatment, the quantity of medications prescribed, and the frequency of the medications' intake were compatible with findings from previous studies conducted in the Asian and Western countries [16].

In addition, interesting results were found in our study regarding dietary habits of the participants that illustrated strong association with poor adherence to antihypertensive treatment. Particularly, the more healthy dietary habits were reported to be practiced by patient, the higher was his adherence to antihypertensive treatment as well. However, the association of poor adherence to antihypertensive treatment with dietary habits was not extensively investigated by previous researches, mostly focusing on the salt intake only.

Health behavior plays crucial role in evaluating the reasons of poor adherence to antihypertensive agents. Results of this study demonstrated that most of HBM components had significant associations with poor adherence to antihypertension treatment. Particular, the strongest predictor of poor adherence were high perceived barriers towards the treatment, making the results consistent with the majority of previous studies in this field [11]. Other two constructs that showed relationship with poor adherence were low perceived severity of the disease and low self-efficacy to comply with hypertension treatment. In contrast to perceived barriers, the association of poor adherence with perceived severity of the hypertension had a borderline significance in our

study and has rarely been reported by previous studies [17]. The perceived high self-efficacy, in other words, positive beliefs regarding the future possibilities in treatment, was found to contribute for the good adherence.

Strengths and limitations

This is a first study that measures adherence level to hypertension treatment using a validated scale on medications adherence among Kazakhstani patients. In addition, the assessment of adherence to hypertension treatment using Health Belief Model constructs have not been previously investigated in studies from Kazakhstan and most Asian countries. Finally, the dietary habits other than reduction of salt intake recommended to hypertension patients were not explored in other studies from Asian countries, thus making it unique for our study. The findings of this study can be used for the improvement of

existing policies by focusing on identified issues. The effective strategies may possibly include the development of educational programs based on HBM model findings.

The study had several limitations as well. First of all, the small sample size of this pilot study could influence the power of the study to detect statistically significant results, and in further studies it is recommended to increase it to valuable numbers. Second, the research was carried out in only one polyclinic, making the results not completely generalizable for all other polyclinics in the city. The geographical area of study probably should be extended including both urban and rural regions. Thirds, because of the self-report survey the participants could have recall bias during the completion of questionnaire.

Conclusion

In conclusion, some factors associated with adherence to hypertension treatment using the Hill-Bone compliance test were unique for Kazakhstan and other Asian countries. In addition, since there are few studies on the determinants of poor adherence among Kazakhstani population, it is important to investigate Hill-Bone compliance test as a tool of adherence measurement for the applicability and psychometric properties within country. By considering the factors associated

with antihypertensive drug adherence the further evaluation of public health programs can be launched using HBM model.

Conflict of interests

The research does not contain any commercial or financial relations that could be estimated as a potential conflict of interest.

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