Health beliefs and medication adherence in patients with hypertension: A systematic review of quantitative studies

Health beliefs and medication adherence in patients with hypertension: A systematic review of quantitative studies

Accepted Manuscript Title: Health Beliefs and Medication Adherence in Patients with Hypertension: A Systematic Review of Quantitative Studies Authors:...

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Accepted Manuscript Title: Health Beliefs and Medication Adherence in Patients with Hypertension: A Systematic Review of Quantitative Studies Authors: Huda Al-Noumani, Jia-Rong Wu, Debra Barksdale, Gwen Sherwood, Esra AlKhasawneh, George Knafl PII: DOI: Reference:

S0738-3991(19)30069-2 https://doi.org/10.1016/j.pec.2019.02.022 PEC 6205

To appear in:

Patient Education and Counseling

Received date: Revised date: Accepted date:

2 July 2018 20 February 2019 22 February 2019

Please cite this article as: Al-Noumani H, Jia-Rong W, Barksdale D, Sherwood G, AlKhasawneh E, Knafl G, Health Beliefs and Medication Adherence in Patients with Hypertension: A Systematic Review of Quantitative Studies, Patient Education and Counseling (2019), https://doi.org/10.1016/j.pec.2019.02.022 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

1 Title page

Title:

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Health Beliefs and Medication Adherence in Patients with Hypertension: A Systematic Review of Quantitative Studies Author names and affiliations:

1. Huda Al-Noumani, PhD, College of Nursing, Sultan Qaboos University, Muscat, Oman. 2. Jia-Rong Wu, PhD, School of Nursing, University of North Carolina at Chapel Hill,

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North Carolina, USA.

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3. Debra Barksdale, PhD, School of Nursing, Virginia Commonwealth University, Virginia,

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USA.

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4. Gwen Sherwood, PhD, School of Nursing, University of North Carolina at Chapel Hill, North Carolina, USA.

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5. Esra AlKhasawneh, PhD, College of Nursing, Sultan Qaboos University, Muscat, Oman.

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6. George Knafl, PhD, School of Nursing, University of North Carolina at Chapel Hill,

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North Carolina, USA.

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Corresponding author: Huda Al-Noumani

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[email protected] Tel: +968 92116739 Permanent address: Sultan Qaboos University College of Nursing, P.O.Box 66, P.C. 123, Alkhoud, Muscat, Oman.

2 Conflict of interest: None declared.

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Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Highlights

Adherence to antihypertensive medications is higher with higher self-efficacy 




Adherence to antihypertensive medications is higher with less perceived 
 barriers.



Medication adherence is higher with stronger beliefs about medication necessity.




Individual patients' beliefs about hypertension and medications should be explored 


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Objective

Abstract

This review synthesizes findings of quantitative studies examining the relationship between

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health beliefs and medication adherence in hypertension. Methods

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This review included published studies in PubMed, CINHAL, EMBASE, and PsycINFO databases. Studies were included if they examined beliefs of patients with hypertension. Quality of the studies was evaluated using the Quality Assessment Tool for Systematic Review of Observational Studies.

3 Results Of the 1,558 articles searched, 30 articles were included in the analysis. Most beliefs examined by studies of this review in relation to medication adherence were beliefs related to hypertension

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severity and susceptibility to its consequences, medication effectiveness or necessity, and barriers to medication adherence. Higher medication adherence was significantly related to fewer perceived barriers to adherence (e.g, side-effects) was fairly consistent across studies. Higher

self-efficacy was related to higher medication adherence. Patients' beliefs and their relationship

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to medication adherence appear to vary unpredictably across and within countries.

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Conclusion

Clinicians should assess beliefs for individual patients. When individual beliefs appear likely to

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undermine adherence, it may be useful to undertake educational interventions to try to modify

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them.

Practical implications

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Clinicians should explore individual patients' beliefs about hypertension and blood pressure medications, discuss their implications for medication adherence, and try to modify

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counterproductive beliefs.

Keyword: Antihypertensive medication, Beliefs, Hypertension, Medication adherence, Systematic review.

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1. Introduction

Hypertension (HTN) is a prevalent health concern around the globe that affects about 40% of the

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world’s population aged 25 years and older [1]. Effective HTN management, using

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antihypertensive medications, is vital and leads to substantial improvements in patients’ health

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outcomes (e.g., blood pressure (BP) control, complications risk reduction) and in cost reduction [2–4]. Despite the guidelines regulating HTN management, control of BP remains a challenge.

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Proper adherence to antihypertensive medications is only 50% or less, which contributes to poor control of BP [5].

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Medication adherence is linked to several factors [6,7] that require understanding before implementation of strategies to improve adherence to antihypertensive medications [8–10]. Patients’ beliefs about health, illness, and treatment are significant predictors of medication adherence in patients with various chronic illnesses including HTN [11–16]. In treating HTN,

5 understanding patient’s beliefs in relation to medication adherence is fundamental because HTN is silent and asymptomatic in nature. Thus, patients might have misperceptions about HTN, its severity, and the significance of its management [5,17,18] that could influence their adherence to

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medication. After a thorough search of related literature, we found two reviews focused on barriers to

antihypertensive medication adherence, but they included very limited studies concerning beliefs as possible barriers [19,20]. Another review focused on examining patients’ beliefs on HTN and medication adherence [18]; however, this was a review of qualitative studies and excluded

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findings from quantitative studies. Over the past decades, several quantitative studies have found

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that various beliefs held by patients influence medication adherence [21–26]; nevertheless, we

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identified no reviews summarizing and synthesizing these studies’ findings.

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1.1.Aim

This systematic review of quantitative studies aimed to identify different HTN-related health

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beliefs and to examine their relationship to medication adherence. The examination of the

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relationship between different patients’ beliefs and adherence to antihypertensive medications

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among patients with HTN will guide the development of effective and customized strategies to enhance medication adherence by incorporating patients’ specific beliefs into patient-centered

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treatment plans.

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2. Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was used to guide the review [27]. The search, in collaboration with a librarian, included articles published from 1980 to end of November 2018, retrieved from PubMed, CINHAL, EMBASE, and PsycINFO databases. To retrieve appropriate articles, the following Medical Subject

6 Headings (Mesh) and text-words were used in PubMed: adherence [tw] OR compliance [tw]) AND (attitude*[tw] OR belief*[tw] OR perception*[tw] OR perceiv*[tw] OR psychosocial [tw]) AND ("Antihypertensive Agents"[Mesh] OR "Antihypertensive Agents" [Pharmacological

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Action] OR antihypertensive agent*[tw] OR medication*[tw]) AND (hypertension [tw] OR hypertensive [tw]. The same search strategy was used with other databases as well, with Mesh

and text-words appropriately modified to fit each database. The search was restricted to English, peer-reviewed, and full text research articles. There were no limitations on geographical location, year of publication, or type of patients’ beliefs because this review aimed to identify all possible

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beliefs and to include all possible studies matching the purpose of this review. All authors

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reviewed the search strategy.

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2.1. Eligibility Criteria

Studies were included in the review if they (a) were quantitative; (b) included participants with

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HTN taking at least one antihypertensive medication who were ≥18 years (because a majority of

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literature on HTN and medication adherence included participants with a minimum age of 18

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years); (c) addressed patients’ beliefs; and (d) measured antihypertensive medication adherence as an outcome variable. Studies were excluded if they (a) were qualitative, as a review of

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qualitative studies was already conducted [18]; (b) focused only on providers’ beliefs; or (c) included subjects with concomitant morbidities in addition to HTN or had medications other than

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antihypertensive medications because having concomitant morbidities will influence patients’ perceived burdens and the severity of a disease and its management [28] and the focus of this review was to identify HTN-related beliefs in specific. 2.2. Review Process

7 All retrieved articles were organized and screened using a Microsoft Excel spread sheet and Refworks reference management software. After removing duplicates, articles’ titles and abstracts were assessed for eligibility. Then, the full-text articles were screened and data of the

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eligible articles were extracted into a table. Extraction of the data was based on the following categories: authors, theory, sample size and population, mean age and gender, types of beliefs, adherence measure, and findings. Quality of the studies was evaluated using the Quality

Assessment Tool for Systematic Review of Observational Studies (QATSO) checklist [29],

which was slightly modified to fit the review (Table 1). The QATSO consists of items to assess

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external validity, bias and confounding, and measures’ validity/reliability. Total quality score is

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the total score divided by total number of items multiplied by 100. We referred to studies as bad

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(0-33%), Satisfactory (34-66%), and good (67-100%) quality (Appendix 1). Relevant articles

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were not excluded based on quality evaluation because the purpose of the review was to identify as many beliefs as possible. Articles screening, review, and quality evaluation was done by the

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first author (HA) and verified by the second author (JRW).

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3. Results

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3.1. Selection of the Studies

The electronic search yielded 1,558 articles (Figure 1). After removing duplicates (n= 383),

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1,175 articles remained. Of these, 924 articles were excluded after title and abstract screened applying inclusion and exclusion criteria. The remaining 251 full text articles were further

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screened for eligibility. Of these, 221 articles were excluded because these articles: (a) included subjects who had other comorbidities in addition to HTN (n= 92); (b) did not address patients’ beliefs (n=27); (c) did not measure medication adherence or measured adherence to other therapeutic behaviors (e.g., diet and exercises) (n=53); (d) measured adherence of medications

8 other than antihypertensive (n=8); (e) did not measure adherence as an outcome variable (n=8); or (f) were qualitative studies (n=7). The remaining 30 studies were included in the systematic review.

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Methodological quality evaluation of the studies revealed that 77% (n=23) of the reviewed studies scored from satisfactory to good (Table 1). Although 87% (n=26) of the studies reported validity and reliability of the adherence measures, majority of them used only self-reporting

measures (n=24), and the remaining used either objective measure only, or both. However, selfreport measures, such as Morisky Medication Adherence Scale (MMAS), have been correlated

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with other objective measures such as pharmacy refills and the Medical Events Monitoring

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which could limit the studies’ external validity.

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System (MEMS) [30–32]. Moreover, majority of studies used non-probability sampling (n=18),

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3.2. Study Characteristics

The 30 studies reviewed appeared from 1980−2018 (Table 2). The studies’ sample sizes ranged

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from 45 to 1,367 participants with a total of 8,414 participants. The samples represented people

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from the following countries: Canada (n=1), Brazil (n=2), South Africa (n=1), Northern Ireland

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(n=1), Malaysia (n=1), the Netherlands (n=1), Taiwan (n=1), India (n=1), Peru (n=1), Iran (n=2), the United Kingdom (n=1), Australia (n=1), Nigeria (n=1), Oman (n=1), China (n=1), Cameroon

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(n=1) and the United States (n=12). Studies from the United States included the following ethnicities: White American, Black/African American, Native American, Hispanic, Chinese

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American, and Caucasian. The mean age of participants included in the studies ranged from 42−75 years old. Twenty-eight studies, (93%), had cross-sectional designs, and only two studies had a longitudinal design [33,34]. Of the 30 included studies, 11 included a randomized sample

9 [31,33–42]. The majority of the studies used one measure to assess medication adherence, one study used three measures (i.e., medication event monitoring system, Morisky medication adherence scale (MMAS), and the medication adherence report scale) [43], and another study

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used four measures of medications adherence (i.e., pill counts, serum uric acid, urinary chlorthalidone, and self-reports) [33]. Self-report measures were used by 28 studies; of these, the MMAS was used in 13 studies. Forty percent of studies (n= 12) used a theoretical model: the

health beliefs model (n= 7) [36,40,44–48], self-efficacy and the theory of planned behavior (n= 1) [49], self-regulation model (n= 1) [50], medication adherence model (n= 1) [51],

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commonsense self-regulation model (n= 1) [43], and ecological system theory (n= 1) [52].

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3.3. Themes on Relationship Between Beliefs and Medication Adherence

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Findings of this review were categorized based on belief types: (a) beliefs about hypertension; (b)

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beliefs about antihypertensive medications; and (c) other patient-related beliefs (Table 3) and how these beliefs related to antihypertensive medication adherence (Table 4).

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1.3.1. Beliefs About Hypertension and Medication Adherence Twelve studies (40%) examined beliefs about the severity of HTN and susceptibility to HTN

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complications in relation to antihypertensive medication adherence. Beliefs about severity of

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HTN, which are patients’ perceptions about the seriousness of HTN were reported in ten studies; five studies found that stronger beliefs about HTN severity was significantly related to higher medication adherence [33,40,47,48,53] whereas five studies reported no relationship [36,38,44– 46].

10 Patients’ beliefs regarding their susceptibility to HTN complications were reported in eight studies and revealed mixed findings. Two studies reported that as patient believe that they are at higher risk of complications, they significantly demonstrated higher medication adherence

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[40,54]. One study found that as that as patient believe that they are at higher risk of complications, they significantly demonstrated lower medication adherence [50], and five studies reported no relationship [36,38,44,45,47]. 1.3.2. Beliefs About Medications and Medication Adherence

Twenty studies (67%) reported perceived barriers to taking antihypertensive medications and

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beliefs about medications effectiveness/benefits, safety, and necessity. Perceived barriers to

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taking medications were reported by 16 studies; of these, 12 studies found that stronger beliefs in

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barriers to taking medications such as medications’ side effects, high cost, bad taste, and harmful

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effects, were significantly associated with lower medication adherence [36,38–40,44,48,55–60]. However, four studies reported no relationship between beliefs concerning side effects of

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adherence [37].

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medication and medication adherence [46,47,51] or between medication cost and medication

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Additionally, of 11 studies examining beliefs about effectiveness, necessity, and safety of medications, seven examined the relationship between medications’ effectiveness/benefits and

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medication adherence; of these, two studies reported that stronger beliefs about the effectiveness of antihypertensive medications were associated with higher medication adherence [40,60] and

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five studies found no relationship [33,35,36,38,47]. Of the five studies examining beliefs about medications’ necessity and safety, only two showed that higher adherence is related to higher perceived medication necessity [46] and safety [33]. 1.3.3. Other Beliefs and Medication Adherence

11 Fifteen studies examined other beliefs in relation to antihypertensive medication adherence. These studies reported that higher adherence was related to (a) higher self-efficacy, patients’ beliefs about their own capabilities to perform a certain behavior (n=7) [34,40,46,48–50,61]; (b)

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higher internal locus of control, (i.e., the degree to which people believe that their health status is influenced by their own behavior (n=1) [39], (c) higher subjective norms (i.e., beliefs that taking medications is important because significant others believe it is important (n=1) [49]; (d)

perceived good general health (n=1) [62]; (e) perceived good relationship with health care

providers (n=2) [38,42]; (f) perceived good relationship with spouses (i.e., marital function)

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(n=1) [63]; (g) perceived good control over HTN (n=1) [38]; and (h) perceived strong family

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support (n=1) [41]. However, medication adherence was lower with more perceived stress (n=1)

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[62] and in another study, with control over HTN (n=1) [64]. Other studies reported no

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relationship between adherence and perceived stress (n=1) [52], perceived general concerns about health (n=1) [38], and Self-efficacy (n=1) [47].

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1.1. Discussion

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2. Discussion and Conclusion

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This review identified 30 quantitative studies examining the relationships between different patients’ beliefs and medication adherence among patients with HTN. The review identified that

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beliefs about medications, beliefs about HTN, and self-efficacy are the commonly reported and studied beliefs in relation to antihypertensive medication adherence. This review also showed

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that Health Belief Model is the most commonly used theoretical framework to guide studies' design, questions, measures, and discussion. Majority of the studies examining beliefs about medications (12 out of 16) found a negative association between barriers to taking medications and medication adherence; these findings are

12 similar to those of other reviews conducted among patients with HTN and other chronic diseases [16,18,19,65]. Additionally, our findings are consistent with those of studies included in the meta-analysis by Horne and colleagues [14], who found that medication adherence was

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significantly higher in patients with fewer concerns regarding medications’ side effects and safety. Findings from this review and others underline the importance of assessing patients’

perceived barriers to medication adherence (e.g., side effects) to identify the best strategies for

educating patients regarding medications and enhancing medication adherence. Of these 12, only one study have considered type of antihypertensive medications used by patients [55]; however

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this study reported no association between type of medication and adherence. Type of

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medication in relation to adherence could be considered by future researchers examining barriers

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and concerns related to antihypertensive medication because barriers to adherence could vary

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across medication type.

Majority of studies (73%) in our review reported no relationship between beliefs about

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medication necessity, effectiveness, and safety and medication adherence; this finding is

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inconsistent with Horne and colleagues’ [14] who reported that medication adherence was higher

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among those who believe that medications are effective, necessary, and safe. The inconsistency in findings could be explained by: (a) variation in measures of beliefs about medications as

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studies of this review include different types of beliefs measures such as (BMQ, Health beliefs model questionnaire, Brief Medication questionnaire, the adherence factor questionnaire, other

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self-report questionnaires) (Table 2), while Horne’s review included studies that only used the Beliefs About Medicine Questionnaire (BMQ); (b) differences in symptoms experienced by patients, as their review included more than 22 different chronic conditions (e.g., cancer, diabetes, HIV, asthma, and depression) that have more evident and severe symptoms than HTN,

13 which could influence patients’ beliefs about disease and medication adherence differently; and (c) difference in total sample size included because Horne’s review included a total sample size of 25,072 compared to 8,414 in the current review; therefore, Horne’s review could had more

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power to detect a relationship between some beliefs and medication adherence. Seven studies in this review reported that stronger beliefs about severity of HTN and their

susceptibility to its complications is related to higher medication adherence, which is consistent with the findings of other reviews examining barriers to medication adherence among patients with HTN [19], patients with chronic conditions [16], and elderly patients [6]. Moreover, six

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other studies of our review reported no association and one found a negative relationship. These

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mixed findings could be related to the influence of culture on how people view illness causality,

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severity, and susceptibility to complications, especially because HTN is silent in nature. In our

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review, studies that examined these beliefs represented people from different countries with different cultural backgrounds (e.g., Canada, Brazil, South Africa, Northern Ireland, Malaysia,

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the Netherlands, Taiwan, India, Peru, Iran, the United Kingdom, Australia, Nigeria, Oman,

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Cameroon, China, and the United States) that might perceive HTN differently. For instance,

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adherence to antihypertensive medications was lower among Hmong Americans who attributed HTN to bad deeds [56] and Chinese who attributed HTN to cultural causality (e.g., imbalance

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between internal and external environment [50]. Accordingly, researchers need to explore and examine how patients' culture could influence their beliefs regarding HTN causality and severity,

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which as a result influence their adherence behavior. Exploring these beliefs will support healthcare providers to understand individual beliefs and design proper educational program related to HTN and its management to improve medication adherence. Another reason for the mixed findings could be attributed to variation in measures of beliefs used; although studies

14 measuring these beliefs used self-report measures, these measures vary in-term of items, validity, and reliability. In this review, higher self-efficacy was significantly related to higher medication adherence, as

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reported in seven studies from Northern Ireland, Australia, Taiwan, Oman, China, the United States and Iran [34,40,46,48–50,61]. Our review is consistent with findings from current

literature among patients with hypertension in addition to other chronic illness (e.g., diabetes, arthritis, and cancer) [16,65,66]. Within the context of HTN, higher self-efficacy is also

associated with higher adherence to other self-care behaviors related to diet, exercise, weight,

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and smoking [67–69]. Several studies showed improved medication adherence and self-care

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activities when self-efficacy was incorporated as a key element in interventions such as mobile

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text message, health education, counseling, and motivational interviewing [70–73]. This

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indicates that self-efficacy is a critical element in behavioral changes and plays a significant role in medication adherence irrespective of different diseases or populations, signifying the necessity

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medications [74–76].

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to empower self-efficacy across different populations to enhance adherence to antihypertensive

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Overall, studies included in this review showed that findings vary in addressing the relationship between different beliefs and medication adherence. While some studies found a positive or a

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negative relationship, others reported no relationship. This variation in findings could be explained by heterogeneity in (a) cultural backgrounds of populations from 17 countries that

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might hold different beliefs related to disease causality and treatment; (b) sample size, which ranged from 45 to 1,367 participants; (c) age, which represented a mean age ranging from 42 −75 years old; and (d) defining and measuring medication adherence because adherence was defined differently as numbers of pills taken per month using a patient report [60], as a total

15 score ≥ 75% on a self-report questionnaire [44], or as a total score of 4 using MMAS-4 [40]. Therefore, variations in findings suggest that beliefs might vary across age groups, populations, and cultures indicating the need to understand different beliefs and how these beliefs could

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influence medication adherence differently. Therefore researchers and clinicians need to consider these variations in beliefs to design successful interventions sensitive to age and culture to improve adherence.

Although this review excluded qualitative studies, however, our findings were consistent with a another systematic review of qualitative study by Marshall (2012), which recommended that

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clinicians and researchers need to understand patients individual perspective on HTN and its

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management to improve medication adherence [18]. Therefore, it is worth noting that despite

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inconsistencies in findings across cultures, patients' knowledge about HTN and medications and

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their perspectives on importance of HTN management should be evaluated by clinicians for any individual patient; this will allow clinicians to link patients' specific beliefs with their

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perspectives and to plan more accurate educational intervention to improve medication

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adherence.

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These findings should take into consideration the following limitations of the studies reviewed. First, the majority of the studies used cross-sectional design with non-probability sampling,

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which limits causal relationships and generalizability of the findings to populations with HTN. Additionally, a majority of studies used self-report measures of medication adherence, which

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could introduce recall bias and overestimation of medication adherence. These studies also used different cut-off points for medication adherence versus non-adherence. Therefore, future studies should focus on measuring adherence using more objective measures and a longitudinal design to assess long-term adherence behaviors and changes over time. This review is subject to several

16 limitations inherent in systematic review. This review is at risk for selection and reporting bias due to the possibility of missing some relevant studies, as this review was limited to English fulltext studies retrieved from four electronic databases. Therefore, non-English studies, books,

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dissertations, and studies obtained manually or through reference lists were not included. Additionally, Qualitative studies have not been included, which could reveal additional findings related to beliefs and medication adherence. Furthermore, this review was limited to patients

with HTN who did not have any concomitant comorbidity or complications from HTN, which

should be considered when dealing with patients having other comorbidities in addition to

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HTN. However, findings of this review emphasize that even with uncomplicated HTN, patients’

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beliefs play a role in medication adherence. Compared to those with significant findings, some

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studies with no association might not been published in the peer-reviewed journals included in

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the databases’ searches, leading to a publication bias. Finally, studies of poor quality were included in reporting this review’s findings.

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1.2. Conclusion

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This review sought to systematically synthesize findings of quantitative studies examining the

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relationship between individual health beliefs held by patients with HTN and antihypertensive medication adherence. The findings of this review emphasize the importance of assessing

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individual beliefs, particularly perceived barriers and self-efficacy, to incorporate them while designing strategies to improve medication adherence. Our recommendations support the

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conclusion of Atreja who reviewed the proven strategies to improve adherence " SIMPLE", which categorized strategies into six categories, of which, improving knowledge, modifying beliefs, and patient and family communication are integral to improving adherence [77].

17 1.3. Practice Implications Clinically, healthcare providers should be aware of and assess beliefs about HTN and medications while caring for patients with HTN across different cultures and age groups. Unlike

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some demographic factors (e.g., age, race, gender) that influence medication adherence among patients with HTN [16], patients’ health beliefs could be potentially modified to enhance

adherence. This necessitates early identification and incorporation of beliefs in designing

effective educational interventions to foster medication adherence to minimize barriers to taking

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medications and maximize positive beliefs about medications benefits.

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22 Priego, C.D. Guerra, M.J.O. Jiménez, M.R. Martínez, R.M. Gómez, E.C. Martin, A.A. Limpo, M.J.A. García, A.M.P. Trujillo, I. de Andrés Cara, A.L. Dugo, M.A. ovales, C.A. Taberné, E.M. Salas, A.M. Luque, A.J.V. Martín, R.B. Cielos, M.P. Díaz, I.O. Caro, C.J.P. de Torres, J.G. Lama, A.M. Cuesta, Effectiveness of motivational interviewing to improve therapeutic adherence in patients over 65 years old with chronic diseases: A cluster randomized clinical trial in primary care, Patient Educ. Couns. (2015). doi:10.1016/j.pec.2015.03.008. C. Pradier, L. Bentz, B. Spire, C. Tourette-Turgis, M. Morin, M. Souville, M. Rebillon, F. JeanGabriel, A. Pesce, P. Dellamonica, Efficacy of an educational and counseling intervention on adherence to highly active antiretroviral therapy: French prospective controlled study, HIV Clin. Trials. (2015).

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A

CC

EP

TE

D

M

A

N

U

SC RI PT

[73]

A

N

U

SC RI PT

23

TE

D

PubMed (n= 667) Embase (n= 745) CINAHL (n= 112) PsycINFO (n= 34)

M

Figure 1: Flow diagram of selection process for study inclusion

383 duplicate

CC

EP

1,558 articles identified through database searching

A

1,175 articles titles and abstracts screened

924 articles excluded

221 full text articles excluded: 251 full text articles assessed for eligibility

 6 were books, not research articles, dissertation.  8 were not in English.  92 addressed other comorbidities  53 did not measure medication adherence, but measure adherence to other therapeutic behaviors..  27 did not address patients’ beliefs or perception  8 measures adherence of other

D

TE

EP

CC

A

SC RI PT

U

N

A

M

24

N U SC RI PT

25

Sampling Method

Adherence Measure validity and Reliability

Adidja, et al.[35]

Probability

No

Yes

self-report

Yes

50%

Satisfactory

Al-Noumani, et al. [46]

Non-probability

No

Yes

self-report

Yes

33%

Bad

Alison,et al. [78]

Non-probability

No

Yes

Objective

Yes

60 %

Satisfactory

Bane et al., [49]

Non-probability

No

Yes

Objective

Yes

60 %

Satisfactory

Chen et al [50]

Control of Confounding factors

Total Percentage*

Quality Score**

Yes

Yes

self-report

Yes

80 %

Good

Non-probability

No

Yes

Objective

Yes

60 %

Satisfactory

No

No

self-report

NA

0%

Bad

Non-probability

CC E

Daniell & Veiga [58]

Adherence Measure (Objective, self-report,)

Probability

PT

Brown & Segal [36]

ED

Authors / Pub Year

M

Response Rate mentioned

A

Table 1: Quality Assessment of the studies included in the review

Probability

No

Yes

self-report

Yes

60 %

Satisfactory

Dijkstra et al [54]

Non-probability

No

No

self-report

Yes

20 %

Bad

Fernandez-Arias et al [57]

Non-probability

No

Yes

self-report

Yes

40 %

Satisfactory

Gilbert et al [61]

Non-probability

Yes

Yes

Objective

NA

75 %

Good

Hall et al [52]

Non-probability

No

Yes

self-report

Yes

40 %

Satisfactory

A

Dennis et al [37]

N U SC RI PT

Non-probability

Yes

Yes

self-report

Yes

60 %

Satisfactory

Haynes et al, [33]

Probability

Yes

Yes

Objective

No

80 %

Good

Hershey et al, [38]

Probability

Yes

No

self-report

Yes

60 %

Satisfactory

Hong et al [39]

Probability

No

Yes

self-report

Yes

60 %

Satisfactory

Non-probability

No

Yes

self-report

NA

25 %

Bad

Probability

No

Yes

self-report

Yes

60 %

Satisfactory

Kamran et al, [40]

ED

Hsu et at [51]

M

Hassan et al, [44]

A

26

Non-probability

No

Yes

self-report

NA

25 %

Bad

Larki et al., [47]

Non-probability

No

Yes

self-report

Yes

33%

Bad

Probability

Yes

Yes

self-report

Yes

80 %

Good

Probability

No

Yes

Objective

NA

75 %

Good

Patel & Taylor [64]

Non-probability

Yes

Yes

self-report

No

40 %

Satisfactory

Peltzer [60]

Non-probability

No

Yes

self-report

No

20 %

Bad

Non-probability

No

Yes

self-report

Yes

40 %

Satisfactory

Probability

Yes

Yes

self-report

Yes

67%

Good

Non-probability

No

Yes

self-report

Yes

40 %

Satisfactory

Morisky et al, [62]

A

CC E

Olowookere et al, [41]

PT

Khan et al., [59]

Richardson et al, [55] Schoenthale et al.,[34]

Trevino et al, [63]

N U SC RI PT

27

Ungari & Fabbro [42]

Probability

No

Yes

self-report

No

40 %

Satisfactory

Wong et al, [56]

Non-probability

Yes

No

self-report

Yes

40 %

Satisfactory

Yang et al., [48]

Probability

No

Yes

self-report

Yes

50%

Satisfactory

A

CC E

PT

ED

M

A

Note: NA = Not Applicable. *Scoring: Total score (0/1) divided by total number of items multiplied by 100 **Bad = 0 - 33%; Satisfactory = 34 - 66%; Good = 67 – 100%

Authors/Year

Adidja, et al., [35]

Theory Used None

Design

Crosssectional

Sample size (n) Population n = 183 Cameroon

HBM

Crosssectional

n= 45

M=52

Bane et al, [49]

Self-efficacy

ED

Commonsense self-regulation model

Crosssectional

CC E

PT

Alison Phillips, et al. [78]

Crosssectional

A

Theory of planned behavior

Brown & Segal [36]

HBM

Crosssectional

Beliefs Type

Measure of Beliefs

Medication Adherence Measure

1.

Efficacy of medication

1. 1-item self-report question

1.

Morisky Medication Adherence Scale *

1. 2.

Severity of disease Effectiveness of medication Concerns of medication Medication adherence self-efficacy

1.

Beliefs about Medicine Questionnaire 2. Brief Illness Perception Questionnaire 3. Revised Medication Adherence SelfEfficacy Scale

1.

Morisky Medication Adherence Scale *

1.

Necessity of medications

1.

Illness perception questionnaire 2. Beliefs about Medicine Questionnaire

1.

Perception of self1. efficacy 2. Perception of subjective norms

1. Self-efficacy scale 3. 2. Theory of Planned 4. Behavior questionnaire

1. Self-report 2. Patient medication report*

Perception of susceptibility Perception of severity Benefits of medication Cost of medication Side-effects of medication

1. Health belief model questionnaire

1. Self-report*

65% (F)

64% (F)

M

Oman

Mean Age Gender (Female) M=60

A

Al-Noumani, et al., [46]

N U SC RI PT

Table 2: Characteristics of the studies

28

3. 4.

n = 71

M=68

White, AfricaAmerican, Asian, Native American, Hispanic

63% (F)

n = 139

M= 52

1.

Northern Ireland

50% (F),

2.

n = 300

M= 60

1.

AfricanAmerican/White Americans

56% (F)

2. 3. 4. 5.

Medication Event Monitoring System* 2. Morisky Medication Adherence Scale * 3. Medication Adherence Report Scale *

Self-Regulation model

Crosssectional

n = 277

M=66

Taiwanese

None

Crosssectional

n = 69

None

Gilbert et al, [61]

None

A

FernandezArias et al, [57]

Hall et al, [52]

Cross sectional

Ecological System Theory

n = 608

ED

None

CC E

Dijkstra et al, [54]

None

Crosssectional

PT

Dennis et al, [37]

Crosssectional

Crosssectional

Crosssectional

Illness perception Self-efficacy (Treatment and personal control)

67% (F)

1. 2. 3.

Side effects of medication Cost of medication Doctor-patient communication

M=58

1.

Medication barriers Cost

1.

HTN severity

Medication harm Medication Concern Medication Necessity

1. Beliefs about Medicine Questionnaire

1. Morisky Medication Adherence Scale (8items)*

1. 2.

40% (F)

M=64

M

Brazilian

1. 2.

A

Daniell & Veiga, [58]

N U SC RI PT

Chen et al, [50]

1.

29

1.

1.

Illness perception questionnaire

Self-report about environmental and personal factors

Brief Medication Questionnaire

Urban Indian

49% (F)

n = 176

M= 62

Netherlands

52% (F)

n = 115

M=62

Peru

67% (F)

1. 2. 3.

n = 110

M= 59

1.

Self-efficacy

1.

Australian

55% (F)

n = 45

28-60

1.

Perceived stress

1. Perceived Stress scale

Hispanic

56% (F)

1.

2.

1-item self-report question

5-point scale selfreport

1.

1.

The Medication Adherence Inventory*

Instrument to Evaluate Attitudes Regarding Taking Medications

Brief Medication Questionnaire *

1. Self-report (1-item)

Prescription re-fill* Self-report of consumption

1. Morisky Medication Adherence Scale (8items)*

HBM

Crosssectional

n = 240

N U SC RI PT

Hassan et al, [44]

M= 55

Malaysian

1. 2.

50% (F)

3.

None

Longitudin al/ 6 months follow-up

n = 134

M= 42

Canadian

100% (M)

1. 2. 3.

Severity of HTN Susceptibility to HTN consequences Barriers (complex regimen, cost)

1. 35-items self-report questionnaire

1. Self-report*

Medication safety Medication benefits HTN seriousness

1.

1. 2.

Self-report measure

Crosssectional

M

None

n = 132

ED

Hershey et al, [38]

None

CC E

Hong et al, [39]

PT

92% Black and white Americans

A

Hsu et al, [51]

Medication Adherence Model

Crosssectional

Crosssectional

M= 52 61% (F)

1. 2. 3. 4. 5. 6. 7.

n = 588

M= 63

White/African American

2% (F)

n = 94

M= 75

Chinese American

63% (F)

1.

2.

1.

2. 3.

Susceptibility Severity of HTN Benefits of medications Concerns about health Control over HTN Dependence on the provider Barriers

Barriers (side-effects, complex regimen, forgetting) Internal locus of control

Necessity and effectiveness of medication Side-effects medication Safety

1.

1. 2.

1.

4.

Pill count* Serum Uric acid and potassium determination* Urinary chlorthalidone and hydrochlorothiazide* Self-report

1.

Self-report

3.

A

Haynes et al, [33]

30

Self-report measure

Nine-items Measure Health locus of control Scale

The Adherence factor questionnaire

1. Self-report (Morisky 4items)*

1. 2.

Hill-Bone Compliance* The Adherence Factor Questionnaire*

HBM

Crosssectional

N U SC RI PT

Kamran et al., [40]

n = 671

>30

Iran

None

Crosssectional

CC E

Olowookere et al, [41]

None

A

Patel & Taylor, [64]

None

None

M

Crosssectional

>18

Crosssectional

Crosssectional

Crosssectional

Health belief model questionnaire

Side-effects

1. 1-item question

1. Morisky Medication Adherence Scale (4items)*

1.

39-items questionnaire

1.

Hypertension selfcare activity level effects (H-Scale)*

3. 4. 5.

Severity of HTN Susceptibility to HTN consequences Benefits of medications Barriers Self-efficacy

1. 2. 3.

Health status Social support Stress

1.

Attitude toward Hypertension Social support scale 4-items stress scale

1.

Self-report (Morisky 4-items, & 8- items)* Blood pressure

Perceived social support family scale

1. Bill count*

62% (F)

N= 152

M= 57

Iran

72% (F)

ED

Morisky et al., [62]

HBM

PT

Larki, et al., [47]

1.

75% (F)

n = 200 UK

1.

3. 4. 5.

Severity of HTN Susceptibility to HTN consequences Benefits of medications Barriers Self-efficacy

A

Khan et al., [59]

1. 2.

31

n = 1367

M= 62

American

59% (F)

n = 420

M= 61

Nigerian

51% (F)

n = 102

M=59

80% white

60% (F)

1. 2.

1.

Family Support

1.

Control over HTN

2. 3. 1.

1.

4-items scale

1. Morisky Medication Adherence Scale (4items)*

2.

1. Self-report (Morisky 4items)*

HBM

Crosssectional

n = 100

N U SC RI PT

Peltzer, [60]

M=61 67% (F)

South African

2. 3.

Benefits of medication Side effects & cost of medication Severity of HTN Susceptibility to HTN consequences

1.

Health belief model scale

1. Self-report on adherence*

1.

Barriers

1.

Net barriers score

1. 2.

Self-report* Provider interview

1.

Self-efficacy

1.

Behavior specific scale

1.

Morisky Medication Adherence Scale *

1.

Marital adjustment and function

1.

32-item dyadic adjustment scale

1. Self- report

1.

Trust in doctors

1.

Self-report questions

1.

Morisky Medication Adherence Scale (4items)*

1. 2.

HTN preventable Side-effects

1.

Self-report questions

1.

self-report

1. 2. 3.

Self-efficacy Severity of hypertension Barriers to medications

1.

Self-report questionnaire

1.

Morisky Medication Adherence Scale *

4. 5.

None

Crosssectional

n = 197 American

None

Longitudin al study

N= 593

M

Schoenthaler et al., [34]

M= 54

A

Wong et al., [56]

Yang et al., [48]

Crosssectional

PT

None

CC E

Ungari & Fabbro, [42]

None

ED

Black/African American Trevino et al., [63]

None

HBM

Crosssectional

Crosssectional

Crosssectional

68% (F)

A

Richardson et al, [55]

32

M=58 63% (F)

n = 109

M= 50

American

58% (F)

n = 109

> 20 yrs

Brazilian

84% (F)

n = 323

M=58.

Hmong American

60% (F)

n = 745

M=56.

Chinese

54% (F)

Note: HBM = Health Belief Model; M = Mean age; F = Female * Reliability and validity reported

A ED

PT

CC E A

M

N U SC RI PT 33

34

A

CC

EP

TE

D

M

A

N

Subjective norms

Individual believes on benefits of taking medication or action Individual believes on undesirable/harmful effects of medication Individual believes on curability of illness by medication Individual believes on his/her ability to successfully manage illness Individual believes spiritual practice guide medication taking and relief illness and sideeffects Individual believes on the importance to take medication because significant others believe on its importance.

U

Benefits Side effects Treatment control Self-efficacy Spirituality

Definition Perception about susceptibility to HTN complications Perception about seriousness of HTN Perception about effectiveness of antihypertensive medications to control BP Individual believes on illness-related discomfort Individual believes on importance of medication to manage illness

SC RI PT

Table 3: Beliefs Definitions Belief Susceptibility Severity Illness control Illness burden Necessity

N U SC RI PT

Table 4: Findings of studies in the review

35

1. Beliefs about hypertension Positive association

Higher perceived seriousness of HTN is related to higher medication adherence.

No association

Perceived seriousness of HTN is not related to medication adherence.

Positive association

Higher perceived susceptibility to HTN/ complications is related to higher medication adherence.

No association

Perceived susceptibility to HTN/ complications is not related to medication adherence.

A

CC E

PT

Susceptibility

ED

M

A

Severity

Haynes [33] * Kamran [40] *** Larki [47]* Wong [56] *** Yang [48] ** Al-Noumani [46] Brown [36] Hassan [44] Hershey [38] Peltzer [60] Dijkstra [54]* Kamran [40]**

Barriers: Side-effects Taste Cost Harm

Brown [36] Hassan [44] Hershey [38] Larki [47] Peltzer [60] Chen [50]*

Negative association

Higher perceived susceptibility to HTN/ complications is related to lower medication adherence.

2. Beliefs about Anti-hypertensive Medications Brown [36]* Daniell [58]# Fernandez-Arias [57]** Hassan [44]** Hershey [38]* Hong [39]*** Kamran [40]*** Khan [59]# Richardson [55]* Peltzer [60]*** Wong [56]* Yang [48] ***

Negative association

More perceived barriers to taking medications are related to lower medication adherence.

Benefits/Effectiveness

PT

Necessity

ED

M

A

Adidja [35] Brown [36] Haynes [33] Hershey [38] Larki [47] Alison [78] Fernandez-Arias [57] Hsu [51]

N U SC RI PT

Al-Noumani [46] Dennis [37] Hsu [51] Larki [47] Kamran [40]** Peltzer [60]**

No association

CC E A

Internal locus of control

Perceived barriers to taking medications are not related to medication adherence.

Positive association

Higher perceived effectiveness of antihypertensive medications is related to higher medication adherence.

No association

Perceived medication effectiveness is not related to medication adherence.

No association

Perceived medication Necessity is not related to medication adherence.

Al-Noumani [46]*

Positive association

Higher perceived necessity of antihypertensive medications is related to higher medication adherence.

Haynes [33]*

Positive association

Higher perceived safety of medication is related to higher medication adherence.

Hsu [51]

No association

Perceived medication safety is not related to medication adherence.

Safety

Self-efficacy

36

3. Other Beliefs Al-Noumani [46]* Bane [49]*** Chen [50]** Gilbert [61]# Kamran [40]*** Schoenthaler [34]*** Yang [48]*** Larki [47]

Positive association

Hong [39]*

Positive association

Higher self-efficacy is related to higher medication adherence.

No association

Perceived self-efficacy is not related to medication adherence. Higher Internal locus of control is related to higher

N U SC RI PT

37

medication adherence.

Patient- provider communication

Hershey [38]* Ungari [42]*

Positive association

Higher self-efficacy is related to higher medication adherence.

Control over HTN

Hershey [38]*

Positive association

Higher perceived control over HTN is related to higher medication adherence.

Negative association

Higher perceived control over HTN is related to Lower medication adherence.

Negative association

Higher perceived stress is related to lower medication adherence.

No association

Perceived stress is not related to medication adherence.

Trevino [63]**

Positive association

Perception of good marital relationship is related to higher medication adherence.

Olowookere [41]***

Positive Association

Bane [49]**

Positive association

Stronger perception of family support is related to higher medication adherence Subjective norms are related to higher medication adherence.

General health status

Morisky [62]*

Positive association

Perception of good general health status is related to higher medication adherence.

Concern about health

Hershey [38]

No association

Perceived concern about health is not related to medication adherence.

M

Morisky [62]*

A

Patel [64]**

Stress

Marital Adjustment

PT

Family support

ED

Hall [52]

CC E

Subjective Norms

A

Note: * p-value ≤ .05

** p-value ≤ .01

*** p-value ≤ .001

# used only descriptive statistics

38 Appendix 1. Methodological Quality Assessment Tool Assessment Questions 1 Was the sampling method representative of the population intended to the study? A. Non-probability sampling (including: purposive, quota, convenience and snowball sampling)


2

0

B. Yes

1

Was the measurement tool used valid and reliable?


0

U

A. No

A. By Questionnaire (Self-reported)

C. Both

0

1

Did the investigator(s) control for confounding factors (e.g. stratification/ matching/ restriction/ adjustment) when analyzing the associations (if the study contains purely descriptive results, no association and prediction tests were conducted in the test, please select “Not applicable”)? A. No B. Yes

TE

D

5

1

1

M

B. By Clinical records or lab tests

A

Was the measurement of adherence objective?

N

B. Yes 4

1

Was a response rate mentioned within the study? (Respond no if response rate is below 60) A. No

3

0

SC RI PT

B. Probability sampling (including: simple random, systematic, stratified g, cluster, two-stage and multi-stage sampling)

Score

0 1 NA

EP

C. Not Applicable

Scoring: Total score divided by total number of items multiplied by 100

CC

Methodological Appraisal Score

A

Bad 0 – 33%

Satisfactory 34 - 66%

Good 67 – 100%