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Medication adherence and its associated factors among Chinese community-dwelling older adults with hypertension
Heart & Lung xxx (2014) 1e6
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Medication adherence and its associated factors among Chinese community-dwelling older adults with hypertension Wenru Wang, PhD, RN a, *, Ying Lau, PhD, RN a, **, Aloysius Loo, BSc a, Aloysius Chow, BPsych a, David R. Thompson, PhD, RN, FAAN b, c, d a
Alice Lee Centre for Nursing Studies, Yong Loo Lin School of Medicine, National University of Singapore, Singapore Cardiovascular Research Centre, Australian Catholic University, Melbourne, Australia c Department of Psychiatry, University of Melbourne, Melbourne, Australia d Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 10 February 2014 Received in revised form 2 May 2014 Accepted 2 May 2014 Available online xxx
Objective: To investigate the factors that influence medication adherence in Chinese community-dwelling older adults with hypertension. Methods: A cross-sectional study was conducted with a convenience sample of 382 older adults with hypertension recruited from six health centers in Macao, China. Chinese versions of the Morisky 4-Item Self-Report Measure of Medication-Taking Behavior, Fear of Intimacy with Helping Professionals scale and Exercise of Self-care Agency scale were administered to participants. Results: Participants older than 65 years (b ¼ .118, p ¼ .017), with a low level of education (b ¼ .128, p ¼ .01), who had more than one other common disease (b ¼ .120, p ¼ .015), were on long-term medication (b ¼ .221, p < .001) and who reported higher self-care (b ¼ .188, p ¼ .001), had better medication adherence. Conclusions: Health care professionals should consider these factors when planning medication regimens for Chinese older adults with hypertension, to enhance medication adherence and improve patient outcomes. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Older adults Community-dwelling Chinese Hypertension Medication adherence
Introduction More than one-quarter of the adult population worldwide has hypertension, a major risk factor for other health problems such as coronary heart disease, stroke and kidney disease.1 Annually, millions of people die from hypertension-related diseases and the situation continues to worsen.1 In China, the estimated prevalence of hypertension is 22%.2 Although it has been reported that treatment of hypertension can reduce the risk of stroke by 30e43% and coronary heart disease by 22%, along with reducing the risk of a number of other chronic conditions,3,4 poor adherence to treatment has been observed among Chinese patients with hypertension, with nearly half of them not achieving optimum blood pressure control.5 It is therefore imperative to implement successful measures to control blood pressure in Chinese patients with hypertension so as to reduce morbidity and mortality rates.
* Corresponding author. Alice Lee Centre for Nursing Studies, National University of Singapore, Clinical Research Centre, Block MD 11, 10 Medical Drive, Singapore. Tel.: þ65 66011761; fax: þ65 67767135. ** Corresponding author. Tel.: þ65 60011603. E-mail addresses: [email protected] (W. Wang), [email protected] (Y. Lau). 0147-9563/$ e see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.hrtlng.2014.05.001
The two main strategies for blood pressure control are lifestyle modification and antihypertensive medication.6 Indeed, it has been well documented that antihypertensive medication can be used to effectively manage hypertension and, by extension, its associated problems.6e8 However, the effectiveness of antihypertensive medication hinges on patient medication adherence.6 Poor adherence to antihypertensive medication has been reported to predict higher blood pressure levels, when compared with patients who adhere to their medication routine.6 Despite mounting evidence demonstrating the problems that can be circumvented by effective blood pressure control, poor blood pressure control, largely due to poor antihypertensive medication adherence, remains a critical problem.9e12 Poor medication adherence has been attributed to the “one size fits all” approach that most interventions involve, which fail to consider sub-population patient-specific barriers.9 The identification of such barriers permits the stratification of patients into groups that can be targeted with appropriate, customizable interventions. Moreover, more attention can be placed on people who are less likely to adhere to medication. Since the prevalence of hypertension dramatically increases with age, older adults are more likely to develop cardiovascular disease or have organ damage.1 In addition, studies have reported
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an independent association between hypertension and cognitive impairment, which may result in the development of dementia.13,14 Medication adherence is thus critical to effectively control blood pressure so as to prevent hypertension-related diseases, cognitive impairment and dementia among this older population.14 Previous studies, using various measurement methods, have investigated antihypertensive medication adherence and identified a number of key indicators that are associated with medication adherence.7,9,15e18 Marital status appears to be a mediating factor for medication adherence,18 with married patients with hypertension tending to be more adherent to their medication. Gender also seems to be a factor in medication adherence.7,9 For example, medication non-adherence were linked to lower sexual functioning and higher body mass index in men; while for women, the factors linked to medication non-adherence were the presence of depressive symptoms and quality of relationship with doctors (e.g. low level of trust).7 However, these studies were largely carried out in developed countries in the West,7,9,15e18 where the social, economic and cultural context is significantly different from China. It has been reported that cultural factors might influence antihypertensive medication adherence, and these include health perceptions of hypertension and of Western medications, self-care behavior and health care support.5 A few studies have investigated antihypertensive medication adherence among Chinese patients, but not specifically among an older population.5 The prevalence of chronic conditions like hypertension is high and increasing as people live longer.1 For these people, they are likely to have been prescribed antihypertensive medication to control their blood pressure in order to prevent hypertensionrelated diseases and maintain their quality of life. However, there are instances where some older patients with hypertension do not take their prescribed antihypertensive medication.15 Older patients’ perceptions and attitudes toward their self-care ability have been recognized as barriers to medication adherence19 and a recent study has suggested that older adults’ attitudes about engaging in a helping relationship with health care professionals has a significant impact on their self-care ability and medication adherence. Those with less fear of intimacy with health care professionals had significantly better perceived self-care ability and satisfactory medication adherence.20 Yet, this has not been documented for older patients with hypertension. A better understanding of the factors which contribute to poor antihypertensive medication adherence will help health care professionals develop ways to effectively enhance medication adherence in older patients with hypertension. The World Health Organization (WHO) has recommended that multi-dimensional factors related to medication adherence, such as socioeconomic, health care team and system, and condition-, therapy-, and patientrelated factors, be addressed.21 The current study aims to examine several of these, specifically demographic, health care team (i.e. fear of intimacy with health care professionals), disease-, therapy-, and patient-related (i.e. self-care agency) factors associated with antihypertensive medication adherence in Chinese communitydwelling older adults. Methods Sample and setting The study used a cross-sectional descriptive correlational design and was conducted with a convenience sample of 382 older adults with hypertension visiting one of six health centers across Macao in the People’s Republic of China from January to June 2012. Selfadministered questionnaires were used to collect data from each participant when they visited the health centre for a medical
consultation or health education. Inclusion criteria included those who: (1) had a clinical diagnosis of hypertension, referred to as an average systolic blood pressure (SBP) 140 mm Hg, and/or an average diastolic blood pressure (DBP) 90 mm Hg1; (2) were taking at least one antihypertensive drug; (3) were older than 55 years of age; (4) were able to read and write Chinese; and (5) had no known diagnosis of current or past mental disorder based on the DSM-IV-TR (e.g. anxiety, depression, schizophrenia, bipolar disorder, dementia). The sample size was determined by the number of participants required to maintain statistical power for the statistical tests used in data analysis. For multiple linear regression analysis, we anticipated eight variables which were age, gender, marital status, education level, number of common chronic diseases, long-term antihypertensive medication use, self-care agency, and fear of intimacy with helping professionals that would affect the medication adherence of older patients with hypertension. To achieve a medium effect size, 80% power at .05 significance level (2-sided), a minimum of 108 participants was needed.22 To increase the generalizability of the results and the power of this study, a total of 382 participants were finally recruited in the current study during the data collection period.
Research instruments Morisky 4-Item Self-Report Measure of Medication-Taking Behavior (MMAS-4) Medication-taking adherence was assessed using the MMAS-4, a self-report measure which addresses barriers to medicationtaking,23 widely used in various populations, including older adults.24e26 The MMAS-4 has demonstrated good reliability with Cronbach’s alpha ranging from .69 to .90.24,25,27 The MMAS-4 has been translated into Chinese and the Chinese version uses a 5-point Likert scale from 1 (always) to 5 (never), the higher score implying better medication adherence.28 The Chinese version has good internal consistency, with a Cronbach’s alpha of .73.28 Exercise of Self-Care Agency (ESCA) The Chinese version of the ESCA29 was translated from the original English version,30 developed to measure a person’s ability to engage in his/her self-care activities. Like the English version, the Chinese consists of 43 items grouped into four dimensions: active versus passive response to situations, motivation, knowledge base and sense of self-worth. A 5-point rating scale (i.e. from 0 to 4) is used in this scale, with higher scores indicating higher perceived self-care agency. The Chinese version has been reported to have acceptable reliability and validity, with Cronbach’s alpha ranging from .68 to .92 for the subscales and a test-retest reliability coefficient of .91 for the total scale.29 Fear of intimacy with helping professionals scale (FIS-HP) The FIS-HP30 consists of 18 items which make up three subscales: fear of sharing, openness to intimate sharing and information sharing. Each of the 18 items is scored on a 5-point Likert scale, ranging from 1 (“not at all characteristic of me”) to 5 (“extremely characteristic of me”). Higher scores represent a more negative attitude toward seeking help from a “human service professional.”31 A Chinese version translated from the English version is available and has been used to measure the attitude of fear of intimacy with health care professionals for older Chinese population.21 Both the English and Chinese versions of the FIS-HP have been reported to be valid and reliable measures with satisfactory reliability coefficients, with a Cronbach’s alpha of .78 for the English and .88 for the Chinese versions.31
W. Wang et al. / Heart & Lung xxx (2014) 1e6
Demographic and medical history data Participants’ demographic and medical history data, including age, gender, marital status, education level, comorbidity with other common chronic diseases, long-term (3 months) antihypertensive medication use (including type and route of medication) taken were obtained from a self-reported questionnaire survey. Data collection procedure All older patients who attended health centers during the data collection period were screened according to inclusion and exclusion criteria. The eligible participants were then identified and approached by a well-trained research assistant (RA) at health centers. Upon subjects expressing an intention to participate in the study, the RA introduced the aim, procedure and potential threats and benefits of the study to each potential participant. Once they agreed, the RA obtained a written informed consent from them and then interviewed them using the questionnaires at a meeting room in the health centre. It took approximate 20 min for data collection process for each participant.
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Table 1 Sample characteristics among hypertension old adults (n ¼ 382). Variables >65 55e65 Sex Male Female Marital status Married Single Divorced Widowed Education level None Primary Secondary Tertiary Comorbidity with common chronic Diabetes disease Heart disease Hyperlipidemia Stroke Numbers of common chronic disease One Two Three Long-term (3months) Yes antihypertensive medication use No
Age
Frequency Percentage 205 177 185 197 294 16 10 62 54 175 127 26 107 61 66 3 194 143 45 367 15
53.7 46.3 48.4 51.6 77.0 4.2 2.6 16.2 14.1 45.8 33.2 6.8 28.0 16.0 17.3 .8 50.8 37.4 11.7 96.1 3.9
Ethical consideration Ethical approval was obtained from the Health Bureau of Macao and permission to conduct the study was granted by the health centers. The participants were assured that their refusal to participate in the study would not result in any penalties or differences in their further treatment or care in any way. Their personal information such as name and identification number was not recorded to maintain their privacy and anonymity. They were also informed that all data would be kept strictly confidential and secured. Data were securely locked and access to the data was only granted to the investigators of this study. Data analysis IBM SPSS 22.0 was used for data analysis. Descriptive statistics, including mean, standard deviation (SD), frequency, were used to describe the demographic and medical characteristics of the participants as well as the variables of the Chinese versions of the MMAS-4, ESCA and FIS-HP. Independent sample t-test and ANOVA were used to compare the scale means of the Chinese version of the MMAS-4, ESCA and FIS-HP by demographic and medical variables. Pearson correlation test was used to examine the association between the three study variables, i.e. Chinese versions of the MMAS-4, ESCA and FIS-HP. Multiple linear regression analysis was conducted to determine predictors of medication adherence. All demographic and medical history as well as fear of intimacy with helping professionals and self-care agency, which showed significant association with medication adherence in the model, were entered as independent variables. Results Of 436 Chinese older adults with hypertension invited to participate in the study, 382 (82.5%) completed the questionnaires. The main reasons given for refusal to participate were lack of time, fatigue and reluctance to disclose information. Table 1 summarizes the demographic and medical characteristics of the study participants. Just over half of the participants were older than 65 years of age (53.1%) and were female (51.6%). Most of them were married (77.0%) and just under half had attained primary education (45.8%) and a third secondary education (33.2%). Approximately two-thirds (62.1%) had another chronic disease such as diabetes (28.0%), hyperlipidemia (17.3%) and heart disease
(16.0%). Most (96.11%) had long-term (3months) antihypertensive medication use. Table 2 compares the mean scores of the Chinese versions of the MMAS-4, ESCA and FIS-HP by age group, gender, marital status, education level, number of common chronic diseases and long-term (3 months) antihypertensive medication use of the participants in this study. There were significant differences in the MMAS-4 scores (p < .05) based on the age, marital status, number of other common chronic diseases and long-term (3 months) hypertensive medication use based on independent t-tests and one-way ANOVA. The senior (>65 years) older adults with hypertension and those with long-term (3 months) antihypertensive medication use reported significantly higher MMAS-4 scores than their younger and shortterm medication use counterpart. Participants who were single and who had only one type of other common chronic disease reported the lowest MMAS-4 scores (F ¼ 5.48, p ¼ .005). The Bonferroni post-hoc test was performed and statistical significant difference was revealed between married and single groups (p ¼ .032), and between one type of other common chronic disease and two types (p ¼ .025) or three or more types of other common chronic disease (p ¼ .021). The ESCA mean scores were also significantly different among the participants with different numbers of common chronic diseases (F ¼ 3.74, p ¼ .001) with those who had more than three types of other common chronic diseases reporting the lowest scores. In addition, FIS-HP mean scores was found to be significant difference (t ¼ 2.13, p ¼ .034) between age group with the younger older adults (55e65 years) reporting significantly higher scores than their older counterparts (i.e.>65 years). Table 3 shows the correlation matrix for the MMAS-4, ESCA and FIS-HP. The ESCA showed a low, but positively significant correlation with the MMAS-4 (r ¼ .298, p < .001), whereas the FIS-HP showed a significantly negative correlation with the MMAS-4 (r ¼ .264, p < .001) and C-ESCA (r ¼ .455, p < .001). A multiple linear regression analysis was used to identify the predictors of medication adherence (MMAS-4). Eight variables (age, gender, marital status, education level, number of common chronic diseases, long-term antihypertensive medication use, FIS-HP and ESCA) were selected as the independent variables based on the literature review or showed significant association with the MMAS4 in the bivariate and correlation statistical analysis. The model was statistically significant (F ¼ 8.35, df ¼ 8, p < .001) with the following five predictors of medication adherence, arranged in order of their
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Table 2 Comparison of mean scores of Chinese versions of the MMAS-4, ESCA and FIS-HP by age, gender, marital status, educational levels, numbers of common chronic diseases and long-term hypertensive mediation use. MMAS-4
ESCA
Age >65 (n ¼ 205) 17.5 2.6 132.9 55e65, 64 (n ¼ 177) 16.4 3.2 134.8 3.48 1.01 ta p value .001d .316 Sex Male (n ¼ 185) 17.0 2.8 134.0 Female (n ¼ 197) 17.0 3.1 133.8 a t .14 .08 p value .892 .939 Marital status Married (n ¼ 294) 17.0 2.8 134.6 Single (n ¼ 16) 14.9 3.4 130.9 Divorced (n ¼ 10) 17.0 3.3 125.9 Widowed (n ¼ 62) 17.5 3.0 132.7 b F 3.31 .91 p value .020c .434 Education level None (n ¼ 54) 17.4 2.8 129.6 Primary (n ¼ 175) 17.1 2.8 132.9 Secondary (n ¼ 127) 16.7 3.0 137.2 Tertiary (n ¼ 26) 16.2 3.3 133.3 b F 1.66 2.31 p value .176 .088 Number of common chronic diseases One (n ¼ 194) 16.5 3.0 134.7 Two (n ¼ 143) 17.3 2.7 135.1 Three (n ¼ 45) 17.8 2.8 126.6 Fb 5.48 3.74 d p value .000 .001d Long term (3months) hypertensive medication use Yes (n ¼ 367) 17.1 2.9 133.6 No (n ¼ 15) 13.8 3.0 140.6 ta 4.39 1.37 p value .000d .172
FIS-HP 19.4 19.2
22.0 14.2 25.2 15.2 2.13 .034c
19.8 18.8
22.5 14.1 24.4 15.3 1.28 .199
18.8 18.2 26.6 20.4
23.9 23.9 25.2 21.2 .64 .587
14.9 16.2 12.7 14.4
20.0 19.6 17.3 23.4
26.9 22.7 22.3 27.6 2.05 .106
17.9 13.6 15.2 11.5
19.3 18.0 21.9
22.9 14.7 24.9 15.2 21.4 13.7 1.24 .147
19.3 18.8
23.6 14.8 21.7 15.2 .47 .636
MMAS-4: Morisky 4-Item Self-Report Measure of Medication-Taking Behavior, ESCA: Exercise of Self-Care Agency, FIS-HP: Fear of Intimacy with Helping Professionals. a Independent-sample t-test. b One-way ANOVA. c Significant at the level of p < .05. d Significance at the level of p < .01.
influence on medication adherence, accounting for 26.6% of the variance: medication use (b ¼ .221, p < .001), higher ESCA scores (b ¼ .188, p ¼ .001), low education (b ¼ .128, p ¼ .01), more than one other common disease (b ¼ .120, p ¼ .015), and older than 65 years of age (b ¼ .118, p ¼ .017) (Table 4).
Discussion With an increasingly aging population, and hypertension becoming a common public health problem,1 ensuring adherence to antihypertensive medication use is a priority. A number of
Table 3 Pearson correlations among Chinese versions of the MMAS-4, ESCA and FIS-HP.
FIS-HP ESCA MMAS-4
FIS-HP
ESCA
1 .455a .264a
1 .298a
MMAS-4
1
MMAS-4: Morisky 4-Item Self-Report Measure of Medication-Taking Behavior, ESCA: Exercise of Self-Care Agency, FIS-HP: Fear of Intimacy with Helping Professionals. a Significance at the level of p < .01.
studies have been conducted to investigate the factors associated with antihypertensive drug adherence,15e18 but few focusing specifically on Chinese populations.32,33 The results of this study serve to alert health care professionals to improve medication adherence in this population. The association between age and antihypertensive mediation adherence remains a subject of debate e both negative and positive relationships have been reported in the literature. In this study, age was a predictor of antihypertensive medication adherence with senior older adults reporting better medication adherence than their younger older counterparts. This finding is consistent with other studies.12,27,33e35 It has been proposed that it could be the concomitant presence of more comorbidities in older adults, leading to their perception of themselves being sick and helpless, that causes them to ensure they take their medication.36 It is also argued that senior older adults (i.e. >65 years old) may receive more attention from their family members and this entails more constant reminders to take their medication. However, there are studies that report an inverse relationship between age and medication adherence, implying that age could be dependent on other factors such as family support. It is likely that older adults, with a higher tendency to be absent-minded, exacerbated by poor family support, may lead to their poor antihypertensive medication adherence.27 It would be interesting to investigate the levels of family support among younger old adults and senior old adults to confirm this hypothesis. In this study, education level was found to be a predictor of antihypertensive medication adherence with a low education level being associated with better adherence. This is in contrast with other studies.17,34 Another study conducted on a Chinese population reported no association between education level and medication adherence.32 In China, doctors are regarded as experts and are rarely challenged by patients, especially those with a low education level. These patients follow strictly the medication regimen prescribed: any queries or challenges are highly unlikely as they may be perceived to have result in interpersonal conflict and disharmony.37 Hence, we suggest that a low education level could result in patients having unquestioning obedience and trust in the competence and authority of their physician and, therefore, strict medication adherence. Factors such as the number of common chronic diseases and duration of antihypertensive medication use were found to be predictors of antihypertensive medication adherence. Patients with more chronic diseases and have been on long term antihypertensive medication are more likely to adhere to their medicationtaking schedule. Accordingly, a recent diagnosis of hypertension and a longer duration of antihypertensive medication usage together with comorbidities such as depression have reported to be associated with better medication adherence.5,17,36 In addition, it has been found that non-adherence stems from a reported general dislike for medication albeit patients still comply to their medication regimen to reduce adverse effects from their medical condition.38 These factors, presented together or independently, will influence patients’ attitudes, including perception, acceptance and habit.31 Hypertension is largely asymptomatic and patients may have the misconception that the side effects of antihypertensive medication outweigh its benefits.27 On the other hand, patients with other co-morbidities may experience more obvious benefits brought about by medication and thus be more receptive toward antihypertensive medication. In this study, long-term antihypertensive medication use was the most significant factor influencing adherence. This could be due to participants implicitly and habitually accepting that this maintains physical functioning.34 To our knowledge, this is the first study that incorporates the FIS-HP and the ESCA, the former recently shown to be associated
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Table 4 Factors associated with the Chinese version of the MMAS-4 among hypertensive participants: results of multiple linear regression analyzes. Independent variables
MMAS-4 B
Agec Genderd Marital statuse Education levelf Numbers of common chronic diseaseg Long term (3months) antihypertensive medication useh ESCA FIS-HP
.694 .082 .312 .765 .700 3.323 .694 .082
SE
.289 .290 .349 .295 .287 .735 .289 .290
Beta
.118 .014 .045 .128 .120 .221 .118 .014
t
2.399 .282 .894 2.592 2.438 4.522 2.399 .282
p value
.017a .778 .372 .010b .015a .000b .001b .145
95% confidence interval Lower bound
Upper bound
.125 .488 .999 .185 .135 1.878 .012 .037
1.262 .652 374 1.346 1.264 4.769 .045 .005
MMAS-4: Morisky 4-Item Self-Report Measure of Medication-Taking Behavior, ESCA: Exercise of Self-Care Agency, FIS-HP: Fear of Intimacy with Helping Professionals. a Significant at the level of p < .05. b Significance at the level of p < .01. c 0 ¼ Age 55e65; 1 ¼ Age >65. d 0 ¼ Female, 1 ¼ Male. e 0 ¼ Married, 1 ¼ Single/divorced/widowed. f 0 ¼ Educational level: secondary/tertiary, 1 ¼ educational level: none/primary. g 0 ¼ Numbers of common chronic disease 1, 1 ¼ Numbers of common chronic disease >1. h 0 ¼ No, 1 ¼ Yes.
with medication adherence.21 The findings indicate that exercise of self-care agency is the second most important predictor of antihypertensive medication adherence, with greater perceived self-care translating to better medication adherence. In Chinese culture, being respected by the families and other people around them is essential for the happiness and health of most Chinese elders. Chinese elders believe that they must be able to take care of themselves to obtain respect from others.39 Another point to consider is the evolving structure of the Chinese family. The traditional family structure comprised many members who collectively looked after the elderly and the sick. But with a shrinking family size, this may mean that individualized self-care may become more important to be exercised in the near future. This may usefully inform health care professionals of ways to improve the care of such patients in the future. We propose that with better perceived self-care, patients feel they are in control of their condition and they have the perception that adhering to antihypertensive medication will improve their condition. It is noteworthy that other variations of the FIS-HP may exist in the case of one study that investigated ‘comfort in asking questions of doctor’ as a factor.34 Consistent with other studies,7,20 better attitudes toward seeking help from helping professionals, although not a predictor, was found in this study to be associated with better antihypertensive medication adherence. However, the results of the present study also showed that senior older adults have better attitudes toward seeking help from helping professionals, which did not report any association between age and the FIS-HP in our earlier study,20 though it should be noted that that study investigated FIS-HP in older adults above the age of 65.20 We propose the better attitudes seen in senior older adults may be explained by a cultural attitude where self-dependence is more desirable than depending on helping professional, especially when they have strong family support.32 In spite of this, younger older adults (i.e. age between 55 and 65 years) may have the ability to be independent while the senior older adults may be weaker and have to depend on helping professionals. Since age is associated with FIS-HP (associated with antihypertensive medication adherence) and age is a direct predictor of antihypertensive medication adherence, it is therefore important for helping professionals to place emphasis on the younger older adults. Limitations and Conclusion Although this study provides useful information on predictive factors associated with antihypertensive medication adherence
among Chinese-dwelling older adults with hypertension, the identified five factors accounted for only about 27% of the variance. There might be other variables (e.g. severity of hypertension, quality of health services, and social support) contributing to medication adherence that is not explained by the predictors identified in this study. The sample size for several groups (e.g. marital status, longterm medication use) was clearly unequal and may have resulted in a statistical bias. However this unequal sample size is a realistic reflection of the socio-demographic characteristics of older patients with hypertension. In addition, the generalizability of our results may be restricted due to the participants being recruited from only one city in China. Furthermore, this study suffered from not recording the longitudinal impact of putative associations of the study variables at different time points as this study was a crosssectional design. Hence, future studies should recruit participants from other cities in China in a longitudinal design. The known effectiveness of interventions for enhancing medication adherence among patients with chronic disease remains surprisingly weak.40 Poor knowledge of the factors associated with non-adherence may contribute to the lack of effective interventions. Our study provides some insight into factors associated with antihypertensive medication adherence for Chinese community-dwelling older adults with hypertension. Health care professionals should consider these factors when planning a medication regimen for Chinese older adults with hypertension in order to enhance medication adherence and improve patient outcomes. Acknowledgments The authors acknowledge the help of the participants in the study, the nurses in the health centers who supported it and Assistant Professor Kin Sin Chan for guidance with the statistical analysis. Disclosure statement: No potential conflicts of interest were disclosed. References 1. Aronow WS, Fleg JL, Pepine CJ, et al. ACCF/AHA 2011 expert consensus document on hypertension in the elderly: a report of the American Academy of Neurology, American geriatric Society, American Society for Preventive Cardiology, American Society of hypertension, American Society of Nephrology, association of Black Cardiologists, and European Society of hypertension. J Am Coll Cardiol. 2011;57:2073e2114.
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2. Ma YQ, Mei WH, Yin P, Yang XH, Rastegar SK, Yan JD. Prevalence of hypertension in Chinese cities: a meta-analysis of published studies. PLoS One. 2013;8(3):e58302. 3. Law MR, Morris JK, Wald NJ. Use of blood pressure lowering drugs in the prevention of cardiovascualr disease: meta-analysis of 147 randomised trials in the context of expectations from prospective epidemiological studies. BMJ. 2009;338:b1665. 4. Lemstra M, Alsabbagh MW. Proportion and risk indicators of nonadherence to antihypertensive therapy: a meta-analysis. Patient Prefer Adherence. 2014;8: 211e218. 5. Lee GKY, Wang HHX, Liu KQL, Cheung Y, Morisky DE, Wong MC. Determinants of medication adherence to antihypertensive medications among a Chinese population using Morisky Medication Adherence Scale. PLoS One. 2013;8(4): e62775. 6. Shaw R, Bosworth HB. Baseline medication adherence and blood pressure in a 24-month longitudinal hypertension study. J Clin Nurs. 2012;21:1401e1406. 7. Black HR, Elliott WJ, Neaton JD, et al. Baseline characteristics and early blood pressure control in the CONVINCE trial. Hypertension. 2001;37(1):12e18. 8. Cushman WC, Ford CE, Cutler JA, et al. Success and predictors of blood pressure control in diverse North American settings: the antihypertensive and lipidlowering treatment to prevent heart attack trial (ALLHAT). J Clin Hypertens. 2002;4(6):393e404. 9. Holt E, Joyce C, Dornelles A, et al. Sex differences in barriers to antihypertensive medication adherence: findings from the cohort study of medication adherence among older adults. J Am Geriatr Soc. 2013;61(4):558e564. 10. Ogden LG, He J, Lydick E, Whelton PK. Long-term absolute benefit of lowering blood pressure in hypertensive patients according to the JNC VI risk stratification. Hypertension. 2000;35(2):539e543. 11. Inkster ME, Donnan PT, MacDonald TM, Sullivan FM, Fahey T. Adherence to antihypertensive medication and association with patient and practice factors. J Hum Hypertens. 2006;20(4):295e297. 12. Burnier M. Medication adherence and persistence as the cornerstone of effective antihypertensive therapy. Am J Hypertens. 2006;19(11):1190e1196. 13. Staessen JA, Richart T, Birkenhäger WH. Less atherosclerosis and lower blood pressure for a meaningful life perspective with more brain. Hypertension. 2007;49(3):389e400. 14. Nagai M, Hoshide S, Kario K. Hypertension and dementia. Am J Hypertens. 2010;23(2):116e124. 15. Degli Esposti L. Adherence to antihypertensive medications and health outcomes among newly treated hypertensive patients. Clinicoecon Outcomes Res. 2011;3:47e54. 16. Friedman O, McAlister FA, Yun L, Campbell NR, Tu K. Antihypertensive drug persistence and compliance among newly treated elderly hypertension in Ontario. Am J Med. 2010;23(2):173e181. 17. Morris AB, Li J, Kroenke K, Bruner-England TE, Young JM, Murray MD. Factors associated with drug adherence and blood pressure control in patients with hypertension. Pharmacotherapy. 2006;26(4):483e492. 18. Trivedi RB, Ayotte B, Edelman D, Bosworth HB. The association of emotional well-being and marital status with treatment adherence among patients with hypertension. J Behav Med. 2008;31(6):489e497. 19. Osterberg L, Blaschke T. Drug therapy: adherence to medication. N Engl J Med. 2005;353(5):487e497.
20. Lau Y, Chow A, Chan S, Wang W. Fear of intimacy with helping professionals and its impact on elderly Chinese. Geriatr Gerontol Int. 2014;14(2):474e480. 21. Sabate E. Adherence to Long-term Therapies: Evidence for Action. Geneva: World Health Organization; 2003. 22. Cohen JW. Statistical Power Analysis for the Behavioural Science. 2nd ed. Hillsdale, NI: Lawrence Erlbaum Associates; 1988. 23. Morisky DE, Green LW, Levine DM. Concurrent and predictive validity of a selfreported measure of medication adherence and long-term predictive validity of blood pressure control. Med Care. 1986;24:67e74. 24. Krapek K, King K, Warren SS, et al. Medication adherence and associated hemoglobin A1c in type 2 diabetes. Ann Pharmacother. 2004;38(9):1357e1362. 25. Mann DM. Resistant disease or resistant patient: problems with adherence to cardiovascular medications in the elderly. Geriatrics. 2009;64(9):10e15. 26. Voils CI, Steffens DC, Flint EP, Bosworth HB. Social support and locus of control as predictors of adherence to antidepressant medication in an elderly population. Am J Geriatr Psychiatry. 2005;13(2):157e165. 27. Krousel-Wood M, Thomas S, Muntner P, Morisky D. Medication adherence: a key factor in achieving blood pressure control and good clinical outcomes in hypertensive patients. Curr Opin Cardiol. 2004;19(4):357e362. 28. Tzeng JI, Chang H, Chang C, Lin CC. Assessing analgesic regimen adherence with the Morisky Medication Adherence Measure for Taiwanese patients with cancer pain. J Pain Symptom Manage. 2008;36(2):157e166. 29. Wang HH, Laffrey SC. Preliminary development and testing of instruments to measure self-care agency and social support of women in Taiwan. Kaohsiung J Med Sci. 2000;16(9):459e467. 30. Kearney BY, Fleischer BJ. Development of an instrument to measure exercise of self-care agency. Res Nurs Health. 1979;2(1):25e34. 31. Ingersoll S, Poulin J, Deng R, Shan X, Witt H, Swain M. Fear of intimacy with helping professionals scale: reliability and validity of English and Mandarin versions. J Evid Based Soc Work. 2012;9(4):317e332. 32. Lam P, Lum C, Leung M. Drug non-adherence and associated risk factors among Chinese geriatric patients in Hong Kong. Hong Kong Med J. 2007;13(4):284. 33. Wong MC, Jiang JY, Griffiths SM. Factors associated with antihypertensive drug compliance in 83,884 Chinese patients: a cohort study. J Epidemiol Community Health. 2010;64(10):895e901. 34. Hyre AD, Krousel-Wood MA, Muntner P, Kawasaki L, DeSalvo KB. Prevalence and predictors of poor antihypertensive medication adherence in an urban health clinic setting. J Clin Hypertens. 2007;9(3):179e186. 35. Degli Esposti E, Sturani A, Di Martino M, et al. Long-term persistence with antihypertensive drugs in new patients. J Hum Hypertens. 2002;16(6):439e444. 36. Billups SJ, Malone DC, Carter BL. The relationship between drug therapy noncompliance and patient characteristics, health-related quality of life, and health care costs. Pharmacotherapy. 2000;20(8):941e949. 37. Wang W, Thompson DR, Chair SY, Twinn SF. Chinese couple’s experiences during convalescence from a first heart attack: a focus group study. J Adv Nurs. 2008;61(3):307e315. 38. Svensson S, Kjellgren KI, Ahlner J, Säljö R. Reasons for adherence with antihypertensive medication. Int J Cardiol. 2000;76:157e163. 39. Chen Y. Chinese values, health and nursing. J Adv Nurs. 2001;36(2):270e273. 40. Haynes RB, Yao X, Degani A, Kripalani S, Garg A, McDonald HP. Interventions for enhancing medication adherence. Cochrane Database Syst Rev; 2005: CD000011.
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Medication adherence and its associated factors among Chinese community-dwelling older adults with hypertension Wenru Wang, PhD, RN a, *, Ying Lau, PhD, RN a, **, Aloysius Loo, BSc a, Aloysius Chow, BPsych a, David R. Thompson, PhD, RN, FAAN b, c, d a
Alice Lee Centre for Nursing Studies, Yong Loo Lin School of Medicine, National University of Singapore, Singapore Cardiovascular Research Centre, Australian Catholic University, Melbourne, Australia c Department of Psychiatry, University of Melbourne, Melbourne, Australia d Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 10 February 2014 Received in revised form 2 May 2014 Accepted 2 May 2014 Available online xxx
Objective: To investigate the factors that influence medication adherence in Chinese community-dwelling older adults with hypertension. Methods: A cross-sectional study was conducted with a convenience sample of 382 older adults with hypertension recruited from six health centers in Macao, China. Chinese versions of the Morisky 4-Item Self-Report Measure of Medication-Taking Behavior, Fear of Intimacy with Helping Professionals scale and Exercise of Self-care Agency scale were administered to participants. Results: Participants older than 65 years (b ¼ .118, p ¼ .017), with a low level of education (b ¼ .128, p ¼ .01), who had more than one other common disease (b ¼ .120, p ¼ .015), were on long-term medication (b ¼ .221, p < .001) and who reported higher self-care (b ¼ .188, p ¼ .001), had better medication adherence. Conclusions: Health care professionals should consider these factors when planning medication regimens for Chinese older adults with hypertension, to enhance medication adherence and improve patient outcomes. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Older adults Community-dwelling Chinese Hypertension Medication adherence
Introduction More than one-quarter of the adult population worldwide has hypertension, a major risk factor for other health problems such as coronary heart disease, stroke and kidney disease.1 Annually, millions of people die from hypertension-related diseases and the situation continues to worsen.1 In China, the estimated prevalence of hypertension is 22%.2 Although it has been reported that treatment of hypertension can reduce the risk of stroke by 30e43% and coronary heart disease by 22%, along with reducing the risk of a number of other chronic conditions,3,4 poor adherence to treatment has been observed among Chinese patients with hypertension, with nearly half of them not achieving optimum blood pressure control.5 It is therefore imperative to implement successful measures to control blood pressure in Chinese patients with hypertension so as to reduce morbidity and mortality rates.
* Corresponding author. Alice Lee Centre for Nursing Studies, National University of Singapore, Clinical Research Centre, Block MD 11, 10 Medical Drive, Singapore. Tel.: þ65 66011761; fax: þ65 67767135. ** Corresponding author. Tel.: þ65 60011603. E-mail addresses: [email protected] (W. Wang), [email protected] (Y. Lau). 0147-9563/$ e see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.hrtlng.2014.05.001
The two main strategies for blood pressure control are lifestyle modification and antihypertensive medication.6 Indeed, it has been well documented that antihypertensive medication can be used to effectively manage hypertension and, by extension, its associated problems.6e8 However, the effectiveness of antihypertensive medication hinges on patient medication adherence.6 Poor adherence to antihypertensive medication has been reported to predict higher blood pressure levels, when compared with patients who adhere to their medication routine.6 Despite mounting evidence demonstrating the problems that can be circumvented by effective blood pressure control, poor blood pressure control, largely due to poor antihypertensive medication adherence, remains a critical problem.9e12 Poor medication adherence has been attributed to the “one size fits all” approach that most interventions involve, which fail to consider sub-population patient-specific barriers.9 The identification of such barriers permits the stratification of patients into groups that can be targeted with appropriate, customizable interventions. Moreover, more attention can be placed on people who are less likely to adhere to medication. Since the prevalence of hypertension dramatically increases with age, older adults are more likely to develop cardiovascular disease or have organ damage.1 In addition, studies have reported
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an independent association between hypertension and cognitive impairment, which may result in the development of dementia.13,14 Medication adherence is thus critical to effectively control blood pressure so as to prevent hypertension-related diseases, cognitive impairment and dementia among this older population.14 Previous studies, using various measurement methods, have investigated antihypertensive medication adherence and identified a number of key indicators that are associated with medication adherence.7,9,15e18 Marital status appears to be a mediating factor for medication adherence,18 with married patients with hypertension tending to be more adherent to their medication. Gender also seems to be a factor in medication adherence.7,9 For example, medication non-adherence were linked to lower sexual functioning and higher body mass index in men; while for women, the factors linked to medication non-adherence were the presence of depressive symptoms and quality of relationship with doctors (e.g. low level of trust).7 However, these studies were largely carried out in developed countries in the West,7,9,15e18 where the social, economic and cultural context is significantly different from China. It has been reported that cultural factors might influence antihypertensive medication adherence, and these include health perceptions of hypertension and of Western medications, self-care behavior and health care support.5 A few studies have investigated antihypertensive medication adherence among Chinese patients, but not specifically among an older population.5 The prevalence of chronic conditions like hypertension is high and increasing as people live longer.1 For these people, they are likely to have been prescribed antihypertensive medication to control their blood pressure in order to prevent hypertensionrelated diseases and maintain their quality of life. However, there are instances where some older patients with hypertension do not take their prescribed antihypertensive medication.15 Older patients’ perceptions and attitudes toward their self-care ability have been recognized as barriers to medication adherence19 and a recent study has suggested that older adults’ attitudes about engaging in a helping relationship with health care professionals has a significant impact on their self-care ability and medication adherence. Those with less fear of intimacy with health care professionals had significantly better perceived self-care ability and satisfactory medication adherence.20 Yet, this has not been documented for older patients with hypertension. A better understanding of the factors which contribute to poor antihypertensive medication adherence will help health care professionals develop ways to effectively enhance medication adherence in older patients with hypertension. The World Health Organization (WHO) has recommended that multi-dimensional factors related to medication adherence, such as socioeconomic, health care team and system, and condition-, therapy-, and patientrelated factors, be addressed.21 The current study aims to examine several of these, specifically demographic, health care team (i.e. fear of intimacy with health care professionals), disease-, therapy-, and patient-related (i.e. self-care agency) factors associated with antihypertensive medication adherence in Chinese communitydwelling older adults. Methods Sample and setting The study used a cross-sectional descriptive correlational design and was conducted with a convenience sample of 382 older adults with hypertension visiting one of six health centers across Macao in the People’s Republic of China from January to June 2012. Selfadministered questionnaires were used to collect data from each participant when they visited the health centre for a medical
consultation or health education. Inclusion criteria included those who: (1) had a clinical diagnosis of hypertension, referred to as an average systolic blood pressure (SBP) 140 mm Hg, and/or an average diastolic blood pressure (DBP) 90 mm Hg1; (2) were taking at least one antihypertensive drug; (3) were older than 55 years of age; (4) were able to read and write Chinese; and (5) had no known diagnosis of current or past mental disorder based on the DSM-IV-TR (e.g. anxiety, depression, schizophrenia, bipolar disorder, dementia). The sample size was determined by the number of participants required to maintain statistical power for the statistical tests used in data analysis. For multiple linear regression analysis, we anticipated eight variables which were age, gender, marital status, education level, number of common chronic diseases, long-term antihypertensive medication use, self-care agency, and fear of intimacy with helping professionals that would affect the medication adherence of older patients with hypertension. To achieve a medium effect size, 80% power at .05 significance level (2-sided), a minimum of 108 participants was needed.22 To increase the generalizability of the results and the power of this study, a total of 382 participants were finally recruited in the current study during the data collection period.
Research instruments Morisky 4-Item Self-Report Measure of Medication-Taking Behavior (MMAS-4) Medication-taking adherence was assessed using the MMAS-4, a self-report measure which addresses barriers to medicationtaking,23 widely used in various populations, including older adults.24e26 The MMAS-4 has demonstrated good reliability with Cronbach’s alpha ranging from .69 to .90.24,25,27 The MMAS-4 has been translated into Chinese and the Chinese version uses a 5-point Likert scale from 1 (always) to 5 (never), the higher score implying better medication adherence.28 The Chinese version has good internal consistency, with a Cronbach’s alpha of .73.28 Exercise of Self-Care Agency (ESCA) The Chinese version of the ESCA29 was translated from the original English version,30 developed to measure a person’s ability to engage in his/her self-care activities. Like the English version, the Chinese consists of 43 items grouped into four dimensions: active versus passive response to situations, motivation, knowledge base and sense of self-worth. A 5-point rating scale (i.e. from 0 to 4) is used in this scale, with higher scores indicating higher perceived self-care agency. The Chinese version has been reported to have acceptable reliability and validity, with Cronbach’s alpha ranging from .68 to .92 for the subscales and a test-retest reliability coefficient of .91 for the total scale.29 Fear of intimacy with helping professionals scale (FIS-HP) The FIS-HP30 consists of 18 items which make up three subscales: fear of sharing, openness to intimate sharing and information sharing. Each of the 18 items is scored on a 5-point Likert scale, ranging from 1 (“not at all characteristic of me”) to 5 (“extremely characteristic of me”). Higher scores represent a more negative attitude toward seeking help from a “human service professional.”31 A Chinese version translated from the English version is available and has been used to measure the attitude of fear of intimacy with health care professionals for older Chinese population.21 Both the English and Chinese versions of the FIS-HP have been reported to be valid and reliable measures with satisfactory reliability coefficients, with a Cronbach’s alpha of .78 for the English and .88 for the Chinese versions.31
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Demographic and medical history data Participants’ demographic and medical history data, including age, gender, marital status, education level, comorbidity with other common chronic diseases, long-term (3 months) antihypertensive medication use (including type and route of medication) taken were obtained from a self-reported questionnaire survey. Data collection procedure All older patients who attended health centers during the data collection period were screened according to inclusion and exclusion criteria. The eligible participants were then identified and approached by a well-trained research assistant (RA) at health centers. Upon subjects expressing an intention to participate in the study, the RA introduced the aim, procedure and potential threats and benefits of the study to each potential participant. Once they agreed, the RA obtained a written informed consent from them and then interviewed them using the questionnaires at a meeting room in the health centre. It took approximate 20 min for data collection process for each participant.
3
Table 1 Sample characteristics among hypertension old adults (n ¼ 382). Variables >65 55e65 Sex Male Female Marital status Married Single Divorced Widowed Education level None Primary Secondary Tertiary Comorbidity with common chronic Diabetes disease Heart disease Hyperlipidemia Stroke Numbers of common chronic disease One Two Three Long-term (3months) Yes antihypertensive medication use No
Age
Frequency Percentage 205 177 185 197 294 16 10 62 54 175 127 26 107 61 66 3 194 143 45 367 15
53.7 46.3 48.4 51.6 77.0 4.2 2.6 16.2 14.1 45.8 33.2 6.8 28.0 16.0 17.3 .8 50.8 37.4 11.7 96.1 3.9
Ethical consideration Ethical approval was obtained from the Health Bureau of Macao and permission to conduct the study was granted by the health centers. The participants were assured that their refusal to participate in the study would not result in any penalties or differences in their further treatment or care in any way. Their personal information such as name and identification number was not recorded to maintain their privacy and anonymity. They were also informed that all data would be kept strictly confidential and secured. Data were securely locked and access to the data was only granted to the investigators of this study. Data analysis IBM SPSS 22.0 was used for data analysis. Descriptive statistics, including mean, standard deviation (SD), frequency, were used to describe the demographic and medical characteristics of the participants as well as the variables of the Chinese versions of the MMAS-4, ESCA and FIS-HP. Independent sample t-test and ANOVA were used to compare the scale means of the Chinese version of the MMAS-4, ESCA and FIS-HP by demographic and medical variables. Pearson correlation test was used to examine the association between the three study variables, i.e. Chinese versions of the MMAS-4, ESCA and FIS-HP. Multiple linear regression analysis was conducted to determine predictors of medication adherence. All demographic and medical history as well as fear of intimacy with helping professionals and self-care agency, which showed significant association with medication adherence in the model, were entered as independent variables. Results Of 436 Chinese older adults with hypertension invited to participate in the study, 382 (82.5%) completed the questionnaires. The main reasons given for refusal to participate were lack of time, fatigue and reluctance to disclose information. Table 1 summarizes the demographic and medical characteristics of the study participants. Just over half of the participants were older than 65 years of age (53.1%) and were female (51.6%). Most of them were married (77.0%) and just under half had attained primary education (45.8%) and a third secondary education (33.2%). Approximately two-thirds (62.1%) had another chronic disease such as diabetes (28.0%), hyperlipidemia (17.3%) and heart disease
(16.0%). Most (96.11%) had long-term (3months) antihypertensive medication use. Table 2 compares the mean scores of the Chinese versions of the MMAS-4, ESCA and FIS-HP by age group, gender, marital status, education level, number of common chronic diseases and long-term (3 months) antihypertensive medication use of the participants in this study. There were significant differences in the MMAS-4 scores (p < .05) based on the age, marital status, number of other common chronic diseases and long-term (3 months) hypertensive medication use based on independent t-tests and one-way ANOVA. The senior (>65 years) older adults with hypertension and those with long-term (3 months) antihypertensive medication use reported significantly higher MMAS-4 scores than their younger and shortterm medication use counterpart. Participants who were single and who had only one type of other common chronic disease reported the lowest MMAS-4 scores (F ¼ 5.48, p ¼ .005). The Bonferroni post-hoc test was performed and statistical significant difference was revealed between married and single groups (p ¼ .032), and between one type of other common chronic disease and two types (p ¼ .025) or three or more types of other common chronic disease (p ¼ .021). The ESCA mean scores were also significantly different among the participants with different numbers of common chronic diseases (F ¼ 3.74, p ¼ .001) with those who had more than three types of other common chronic diseases reporting the lowest scores. In addition, FIS-HP mean scores was found to be significant difference (t ¼ 2.13, p ¼ .034) between age group with the younger older adults (55e65 years) reporting significantly higher scores than their older counterparts (i.e.>65 years). Table 3 shows the correlation matrix for the MMAS-4, ESCA and FIS-HP. The ESCA showed a low, but positively significant correlation with the MMAS-4 (r ¼ .298, p < .001), whereas the FIS-HP showed a significantly negative correlation with the MMAS-4 (r ¼ .264, p < .001) and C-ESCA (r ¼ .455, p < .001). A multiple linear regression analysis was used to identify the predictors of medication adherence (MMAS-4). Eight variables (age, gender, marital status, education level, number of common chronic diseases, long-term antihypertensive medication use, FIS-HP and ESCA) were selected as the independent variables based on the literature review or showed significant association with the MMAS4 in the bivariate and correlation statistical analysis. The model was statistically significant (F ¼ 8.35, df ¼ 8, p < .001) with the following five predictors of medication adherence, arranged in order of their
4
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Table 2 Comparison of mean scores of Chinese versions of the MMAS-4, ESCA and FIS-HP by age, gender, marital status, educational levels, numbers of common chronic diseases and long-term hypertensive mediation use. MMAS-4
ESCA
Age >65 (n ¼ 205) 17.5 2.6 132.9 55e65, 64 (n ¼ 177) 16.4 3.2 134.8 3.48 1.01 ta p value .001d .316 Sex Male (n ¼ 185) 17.0 2.8 134.0 Female (n ¼ 197) 17.0 3.1 133.8 a t .14 .08 p value .892 .939 Marital status Married (n ¼ 294) 17.0 2.8 134.6 Single (n ¼ 16) 14.9 3.4 130.9 Divorced (n ¼ 10) 17.0 3.3 125.9 Widowed (n ¼ 62) 17.5 3.0 132.7 b F 3.31 .91 p value .020c .434 Education level None (n ¼ 54) 17.4 2.8 129.6 Primary (n ¼ 175) 17.1 2.8 132.9 Secondary (n ¼ 127) 16.7 3.0 137.2 Tertiary (n ¼ 26) 16.2 3.3 133.3 b F 1.66 2.31 p value .176 .088 Number of common chronic diseases One (n ¼ 194) 16.5 3.0 134.7 Two (n ¼ 143) 17.3 2.7 135.1 Three (n ¼ 45) 17.8 2.8 126.6 Fb 5.48 3.74 d p value .000 .001d Long term (3months) hypertensive medication use Yes (n ¼ 367) 17.1 2.9 133.6 No (n ¼ 15) 13.8 3.0 140.6 ta 4.39 1.37 p value .000d .172
FIS-HP 19.4 19.2
22.0 14.2 25.2 15.2 2.13 .034c
19.8 18.8
22.5 14.1 24.4 15.3 1.28 .199
18.8 18.2 26.6 20.4
23.9 23.9 25.2 21.2 .64 .587
14.9 16.2 12.7 14.4
20.0 19.6 17.3 23.4
26.9 22.7 22.3 27.6 2.05 .106
17.9 13.6 15.2 11.5
19.3 18.0 21.9
22.9 14.7 24.9 15.2 21.4 13.7 1.24 .147
19.3 18.8
23.6 14.8 21.7 15.2 .47 .636
MMAS-4: Morisky 4-Item Self-Report Measure of Medication-Taking Behavior, ESCA: Exercise of Self-Care Agency, FIS-HP: Fear of Intimacy with Helping Professionals. a Independent-sample t-test. b One-way ANOVA. c Significant at the level of p < .05. d Significance at the level of p < .01.
influence on medication adherence, accounting for 26.6% of the variance: medication use (b ¼ .221, p < .001), higher ESCA scores (b ¼ .188, p ¼ .001), low education (b ¼ .128, p ¼ .01), more than one other common disease (b ¼ .120, p ¼ .015), and older than 65 years of age (b ¼ .118, p ¼ .017) (Table 4).
Discussion With an increasingly aging population, and hypertension becoming a common public health problem,1 ensuring adherence to antihypertensive medication use is a priority. A number of
Table 3 Pearson correlations among Chinese versions of the MMAS-4, ESCA and FIS-HP.
FIS-HP ESCA MMAS-4
FIS-HP
ESCA
1 .455a .264a
1 .298a
MMAS-4
1
MMAS-4: Morisky 4-Item Self-Report Measure of Medication-Taking Behavior, ESCA: Exercise of Self-Care Agency, FIS-HP: Fear of Intimacy with Helping Professionals. a Significance at the level of p < .01.
studies have been conducted to investigate the factors associated with antihypertensive drug adherence,15e18 but few focusing specifically on Chinese populations.32,33 The results of this study serve to alert health care professionals to improve medication adherence in this population. The association between age and antihypertensive mediation adherence remains a subject of debate e both negative and positive relationships have been reported in the literature. In this study, age was a predictor of antihypertensive medication adherence with senior older adults reporting better medication adherence than their younger older counterparts. This finding is consistent with other studies.12,27,33e35 It has been proposed that it could be the concomitant presence of more comorbidities in older adults, leading to their perception of themselves being sick and helpless, that causes them to ensure they take their medication.36 It is also argued that senior older adults (i.e. >65 years old) may receive more attention from their family members and this entails more constant reminders to take their medication. However, there are studies that report an inverse relationship between age and medication adherence, implying that age could be dependent on other factors such as family support. It is likely that older adults, with a higher tendency to be absent-minded, exacerbated by poor family support, may lead to their poor antihypertensive medication adherence.27 It would be interesting to investigate the levels of family support among younger old adults and senior old adults to confirm this hypothesis. In this study, education level was found to be a predictor of antihypertensive medication adherence with a low education level being associated with better adherence. This is in contrast with other studies.17,34 Another study conducted on a Chinese population reported no association between education level and medication adherence.32 In China, doctors are regarded as experts and are rarely challenged by patients, especially those with a low education level. These patients follow strictly the medication regimen prescribed: any queries or challenges are highly unlikely as they may be perceived to have result in interpersonal conflict and disharmony.37 Hence, we suggest that a low education level could result in patients having unquestioning obedience and trust in the competence and authority of their physician and, therefore, strict medication adherence. Factors such as the number of common chronic diseases and duration of antihypertensive medication use were found to be predictors of antihypertensive medication adherence. Patients with more chronic diseases and have been on long term antihypertensive medication are more likely to adhere to their medicationtaking schedule. Accordingly, a recent diagnosis of hypertension and a longer duration of antihypertensive medication usage together with comorbidities such as depression have reported to be associated with better medication adherence.5,17,36 In addition, it has been found that non-adherence stems from a reported general dislike for medication albeit patients still comply to their medication regimen to reduce adverse effects from their medical condition.38 These factors, presented together or independently, will influence patients’ attitudes, including perception, acceptance and habit.31 Hypertension is largely asymptomatic and patients may have the misconception that the side effects of antihypertensive medication outweigh its benefits.27 On the other hand, patients with other co-morbidities may experience more obvious benefits brought about by medication and thus be more receptive toward antihypertensive medication. In this study, long-term antihypertensive medication use was the most significant factor influencing adherence. This could be due to participants implicitly and habitually accepting that this maintains physical functioning.34 To our knowledge, this is the first study that incorporates the FIS-HP and the ESCA, the former recently shown to be associated
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5
Table 4 Factors associated with the Chinese version of the MMAS-4 among hypertensive participants: results of multiple linear regression analyzes. Independent variables
MMAS-4 B
Agec Genderd Marital statuse Education levelf Numbers of common chronic diseaseg Long term (3months) antihypertensive medication useh ESCA FIS-HP
.694 .082 .312 .765 .700 3.323 .694 .082
SE
.289 .290 .349 .295 .287 .735 .289 .290
Beta
.118 .014 .045 .128 .120 .221 .118 .014
t
2.399 .282 .894 2.592 2.438 4.522 2.399 .282
p value
.017a .778 .372 .010b .015a .000b .001b .145
95% confidence interval Lower bound
Upper bound
.125 .488 .999 .185 .135 1.878 .012 .037
1.262 .652 374 1.346 1.264 4.769 .045 .005
MMAS-4: Morisky 4-Item Self-Report Measure of Medication-Taking Behavior, ESCA: Exercise of Self-Care Agency, FIS-HP: Fear of Intimacy with Helping Professionals. a Significant at the level of p < .05. b Significance at the level of p < .01. c 0 ¼ Age 55e65; 1 ¼ Age >65. d 0 ¼ Female, 1 ¼ Male. e 0 ¼ Married, 1 ¼ Single/divorced/widowed. f 0 ¼ Educational level: secondary/tertiary, 1 ¼ educational level: none/primary. g 0 ¼ Numbers of common chronic disease 1, 1 ¼ Numbers of common chronic disease >1. h 0 ¼ No, 1 ¼ Yes.
with medication adherence.21 The findings indicate that exercise of self-care agency is the second most important predictor of antihypertensive medication adherence, with greater perceived self-care translating to better medication adherence. In Chinese culture, being respected by the families and other people around them is essential for the happiness and health of most Chinese elders. Chinese elders believe that they must be able to take care of themselves to obtain respect from others.39 Another point to consider is the evolving structure of the Chinese family. The traditional family structure comprised many members who collectively looked after the elderly and the sick. But with a shrinking family size, this may mean that individualized self-care may become more important to be exercised in the near future. This may usefully inform health care professionals of ways to improve the care of such patients in the future. We propose that with better perceived self-care, patients feel they are in control of their condition and they have the perception that adhering to antihypertensive medication will improve their condition. It is noteworthy that other variations of the FIS-HP may exist in the case of one study that investigated ‘comfort in asking questions of doctor’ as a factor.34 Consistent with other studies,7,20 better attitudes toward seeking help from helping professionals, although not a predictor, was found in this study to be associated with better antihypertensive medication adherence. However, the results of the present study also showed that senior older adults have better attitudes toward seeking help from helping professionals, which did not report any association between age and the FIS-HP in our earlier study,20 though it should be noted that that study investigated FIS-HP in older adults above the age of 65.20 We propose the better attitudes seen in senior older adults may be explained by a cultural attitude where self-dependence is more desirable than depending on helping professional, especially when they have strong family support.32 In spite of this, younger older adults (i.e. age between 55 and 65 years) may have the ability to be independent while the senior older adults may be weaker and have to depend on helping professionals. Since age is associated with FIS-HP (associated with antihypertensive medication adherence) and age is a direct predictor of antihypertensive medication adherence, it is therefore important for helping professionals to place emphasis on the younger older adults. Limitations and Conclusion Although this study provides useful information on predictive factors associated with antihypertensive medication adherence
among Chinese-dwelling older adults with hypertension, the identified five factors accounted for only about 27% of the variance. There might be other variables (e.g. severity of hypertension, quality of health services, and social support) contributing to medication adherence that is not explained by the predictors identified in this study. The sample size for several groups (e.g. marital status, longterm medication use) was clearly unequal and may have resulted in a statistical bias. However this unequal sample size is a realistic reflection of the socio-demographic characteristics of older patients with hypertension. In addition, the generalizability of our results may be restricted due to the participants being recruited from only one city in China. Furthermore, this study suffered from not recording the longitudinal impact of putative associations of the study variables at different time points as this study was a crosssectional design. Hence, future studies should recruit participants from other cities in China in a longitudinal design. The known effectiveness of interventions for enhancing medication adherence among patients with chronic disease remains surprisingly weak.40 Poor knowledge of the factors associated with non-adherence may contribute to the lack of effective interventions. Our study provides some insight into factors associated with antihypertensive medication adherence for Chinese community-dwelling older adults with hypertension. Health care professionals should consider these factors when planning a medication regimen for Chinese older adults with hypertension in order to enhance medication adherence and improve patient outcomes. Acknowledgments The authors acknowledge the help of the participants in the study, the nurses in the health centers who supported it and Assistant Professor Kin Sin Chan for guidance with the statistical analysis. Disclosure statement: No potential conflicts of interest were disclosed. References 1. Aronow WS, Fleg JL, Pepine CJ, et al. ACCF/AHA 2011 expert consensus document on hypertension in the elderly: a report of the American Academy of Neurology, American geriatric Society, American Society for Preventive Cardiology, American Society of hypertension, American Society of Nephrology, association of Black Cardiologists, and European Society of hypertension. J Am Coll Cardiol. 2011;57:2073e2114.
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