Medical visits, antihypertensive prescriptions and medication adherence among newly diagnosed hypertensive patients in Korea
Jeong et al. Environmental Health and Preventive Medicine
Medical visits, antihypertensive prescriptions and medication adherence among newly diagnosed hypertensive patients in Korea
Hyoseon Jeong 0
Hyeongsu Kim 0
Kunsei Lee 0
Jung Hyun Lee 0
Hye Mi Ahn 0
Soon Ae Shin 2
Vitna Kim 1
0 Department of Preventive Medicine, School of Medicine, Konkuk University , 1 Hwayang-dong, Gwangjin-gu, Seoul 05029 , South Korea
1 Department of Dental Hygiene, Suwon Women's University , Suwon , South Korea
2 Bigdata Steering Department, National Health Insurance Service , Wonju , South Korea
Objectives: The objective of this study was to assess the antihypertensive medication adherence in patients who were newly diagnosed with hypertension in Korea. Methods: Study subjects were diagnosed with hypertension for the first time by the General Health Screening in 2012 and were 65,919. As indices, visiting rate to medical institution, the antihypertensive prescription rate, medication possession ratio and the rate of appropriate medication adherence were used. The qualification data, the General Health Screening data and the health insurance claims data were used. Resutls: Visiting rate to medical institution within one-year was 42.3%. Gender, age, family history of hypertension, smoking status, drinking frequency, insurance type, BMI, hypertension status, blood glucose level and LDL-cholesterol level were significant variables for visiting a medical institution. Of the study subjects who visited a medical institution, the antihypertensive prescription rate was 89.1%. Medication possession ratio was 70.9% and the rate of appropriate medication adherence was 60.6%. Age, family history of hypertension, smoking status, BMI level, hypertension level, blood glucose level, status, and LDL-cholesterol level were significant variables for the antihypertensive prescription and gender, age, family history of hypertension, smoking status, BMI, hypertension status, and the time of the first visit to a medical institution were significant variables for appropriate medication adherence. Conclusions: This study showed that the antihypertensive medication adherence in patients who were newly diagnosed with hypertension was not relatively high in Korea. National Health Insurance Service should support an environment in which medical institutions and those diagnosed with hypertension can fulfill their roles.
Hypertension; Mass screening; Medication possession ratio; Medication adherence
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Introduction
Hypertension is a primary risk factor of myocardial
infarction and stroke [1], and 29.2% (28.8–29.7%) of the world’s
population is predicted to have hypertension by 2025 [2].
From 1990 to 2013, the number of fatal cases of
hypertensive heart disease increased by 74.1% worldwide [3]. In
addition, 7.6 million premature deaths (~13.5% of the
global total) and 92 million disability adjusted life years
(DALYs; 6.0% of the global total) were attributed to high
blood pressure [4]. In Korea, the death rate associated with
hypertension in 2013 was 10.0 per 100000 people [5], and
the prevalence rate of hypertension was estimated to be
approximately 25.5%, with a total associated medical
insurance expenditure of approximately 2.5 trillion won [6].
Despite the high social and economic burdens related to
hypertension, the management levels for hypertension had
an awareness rate of 65.9%, treatment rate of 60.7%, and
control rate of 42.5% in 2013 [7]. Approaches to increase
the awareness, treatment, or control rates for hypertension
are in high demand, and it has been suggested that one of
the most effective methods is to identify people with
hypertension and treat them as soon as possible.
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Likewise, hypertension has high prevalence rate and also
it causes a lot of medical expenses. If patients who suffer
from hypertension were not treated properly with
medication, it would develop complications which cause actual
dollars of costs [8]. Hypertensive patients could lower their
blood pressure through medical treatment and
improvement of their lifestyle. And continual pharmacological
treatment for hypertension decreases the hospitalization rate
and lowers the risk of complications, such as myocardial
infarction and stroke [9]. The government has a
responsibility to raise a medication adherence in order to prevent
hypertension-induced complications and reduce medical
expenditure. Therefore, it is extremely important to figure
out the medication adherence. There were several studies
that dealt with the rate of visiting a medical institution, the
antihypertensive prescription rate medication possession
ratio or medical adherence among hypertensive patients
[10–12], but they had some limitation like small sample size
or restricted study area except one study that covered all
hypertensive patients were aged 30 years or more and had
received at least one antihypertensive prescription in
Taiwan [13]. Furthermore there were no studies which
purport for measuring medication adherence in Korea.
The aim of this study were to assess the
antihypertensive medication adherence and related factors and to
evaluate the status of medical visit and antihypertensive
prescription, which are the pre-stage of medication
adherence, in order to accurately assess medication
adherence among those who were newly diagnosed with
hypertension by the General Health Screening (GHS) in
Korea 2012. The results could be used as evidence-based
data to establish new healthcare policies and strategies
for an efficient hypertension management.
Materials and methods
Study population
The inclusion criteria for study subjects were as follows:
1) people who participated in the conducts GHS by the
National Health Insurance Service (NHIS) in 2012; 2)
participant who had blood pressure with more than 140
in systolic and 90 in diastolic at the first-step screen test
and the second-step confirmatory test; 3) people who
were diagnosed with hypertension in the result of GHS
and were advised to have a pharmacological treatment
to manage hypertension in the recommendation of GHS.
The exclusion criteria were as follows: 1) participants
who visited medical institutions due to hypertension,
DM, dyslipidemia, myocardial infarction, stroke etc. as
their principal or secondary diagnosis within the
previous 3 years of the date of the second-step
confirmatory test; 2) participants with a history of diagnosis and/
or pharmacological treatment of hypertension, DM,
dyslipidemia, myocardial infarction, stroke etc. based on
the questionnaire of the first-step screening test; and 3)
participants under 30 years of age at the time of the
first-step screening test. The selection process of the
final study subjects was shown in Fig. 1. The subjects for
the first-step of GHS in 2002 were 15,673,188, of whom
11,419,350 (72.8%) completed the first-step screening test.
Of these, 821,973 participants underwent the second-step
confirmatory test of hypertension. Based on the results of
the second-step confirmatory tests, 109,659 participants
were diagnosed with hypertension and were advised to
have a pharmacological treatment. Of these, 43,740 were
excluded according to the exclusion criteria outlined
above. Thus, the final study subjects of the present study
were 65,919.
Study data and variables
The present study used the qualification data, GHS data
of 2012 and data of the insurance claims of medical
institutions from January 2009 to December 2014 that
were extracted from the NHIS administrative system.
The qualification data were used to determine gender
(male/female), age, and type of insurance policy; the
GHS data were used to determine family history of
hypertension, smoking status, alcohol drinking
frequency, obesity status, hypertension status, blood
glucose level, and blood low-density lipoprotein
(LDL)cholesterol level; and the insurance claim data were
used to determine the time of the first visit to a medical
institution and the number of days prescribed medication
for hypertension.
The study subjects were categorized into various
subgroups based on their demographic and clinical
characteristics for the purposes of comparison. They
were categorized based on age (every 10 years of
age), insurance policy (regional, employment-based,
and medical aid), smoking status (nonsmokers,
exsmokers, and smokers), and alcohol drinking
frequency (nondrinking, once to twice per week, and
more than three times per week). They were also
categorized by obesity status according to body mass
index (BMI) (normal: < 23 kg/m2, overweight: 23–
24 kg/m2, obese: 25–29 kg/m2, and extremely obese:
≥ 30 kg/m2), hypertension level using data from the
second-step screening (hypertension stage 1: 140–
159 mmHg systolic pressure or 90–99 mmHg
diastolic pressure, and hypertension stage 2: ≥ 160 mmHg
systolic pressure or ≥ 100 mmHg diastolic pressure),
and blood glucose level using data from the first-step
test (normal: < 126 mg/dL, mild: 126–139 mg/dL,
moderate: 140–199 mg/dL, and severe: ≥ 200 mg/dL).
Blood LDL-cholesterol levels (normal: < 130 mg/dL,
mild: 130–159 mg/dL, severe: ≥ 160 mg/dL).
The subjects were further divided into subgroups
according to the time of their first visit to a
Fig. 1 A selection process of the study subjects
medical institution from the date of the
secondstep confirmatory test (≤ 90 days, 91–180 days, and
181–365 days).
Measurement of major indices
Visiting rate to medical institution
A visit to a medical institution was used as an indicator
of medical use. In this study, the visiting rate to medical
institution was defined as the percentage of
hypertensive patients who visited a medical institution as a
principle or secondary diagnosis more than one time
within 1 year
Visiting rate to
medical institution¼
Number of hypertensive patients who
visited a medical institution within 1
year from the date after diagnosis
Final number of study subjects
Antihypertensive prescription rate
The antihypertensive prescription rate was calculated as
the percentage of subjects who received an
antihypertensive prescription among the subjects who visited a
medical institution.
Antihypertensive prescription rate ¼
Number of subjects receiving an
antihypertensive prescription
Number of study subjects who
visited a medical institution
Medication possession ratio (MPR)
The MPR was defined as the percentage of the sum of
days prescribed antihypertensive medication within 1 year
from the first prescribed day among the subjects who
visited a medical institution over the 365-day period [14, 15].
However, we operationally defined MPR as the percentage of
sum of the purchased days of antihypertensive medication
within 1 year from the first day of purchasing prescribed
medication in this study.
Medication possession ratio ¼
Sum of the purchased days of
antihypertensive medication within
the period of denominator ðone yearÞ 100
One year from the first day of
purchasing prescribed medication
ð365 daysÞ
When the MPR was greater than 100%, it was adjusted
to 100%.
Rate of appropriate medication adherence
Appropriate medication adherence (AMA) was defined as
the value of MPR greater than 80% [16, 17]. The rate of
AMA was calculated as the percentage of subjects who had
a MPR ≥ 80% among those who purchased an
antihypertensive medication based on the prescription by a physician.
Rate of appropriate
medication adherence¼
Number of subjects with
medication possession ratio ≥ 80%
Number of subjects who purchased
an antihypertensive medication
Data analysis
The chi-square test, t test, and analysis of variance were
used for comparisons within subgroups of the following
variables: the rate of visiting a medical institution, the
antihypertensive prescription rate, MPR and rate of AMA,
respectively. Next, multivariate logistic regression analysis
was performed to identify the variables significantly
related to visiting a medical institution, antihypertensive
prescription rate, and rate of AMA. The odds ratios (OR)
and 95% confidence intervals (CI) of the visiting rate were
calculated. Statistical analyses in the present study were
conducted using SAS software (version 9.1; SAS Institute
Inc., Cary, NC, USA). In all analyses, p < 0.05 was taken
to indicate statistical significance.
Visiting (%)
27,895 (42.3)
Family history of hypertension
Smoking status
Drinking frequency (per week)
Insurance type
Hypertension level
Blood glucose level
Blood LDL level
30–39 years
40–49 years
50–59 years
60–69 years
≥70 year
More than 3 times
Employment-based
Extremely obese
Hypertension stage 1
Hypertension stage 2
Data are expressed as the number (%)
P-value from chi-square test for binary outcomes comparing a difference between of nonvisiting and visiting
Results
Visiting rate to medical institution and its related factors
The rate of visiting a medical institution was 42.3%
(n = 27,895), 37.9% for males, and 56.3% for females
(p < 0.001). The rates of visiting a medical institution
according to various variables are shown in Table 1.
Based on the results of multivariate logistic
regression analysis, the variables significantly associated
with visiting a medical institution for hypertension
treatment were gender, age, family history of
hypertension, smoking status, drinking frequency,
insurance type, BMI, hypertension status, blood glucose
level and LDL-cholesterol level. The OR and 95% CI
for the rate of visiting a medical institution for
hypertension according to the variables evaluated are
shown in Table 2.
Antihypertensive prescription rate and its related factors
Of the subjects who visited a medical institution, the
antihypertensive prescription rate was 89.1% (n =
24,861). The antihypertensive prescription rates
according to the variables evaluated are shown in
Table 3. Based on the results of multivariate logistic
regression analysis, the variables significantly
associated with antihypertensive prescription rate were age,
family history of hypertension, smoking status, BMI
level, hypertension level, blood glucose level, status,
and LDL-cholesterol level. The OR and 95% CI for
the antihypertensive prescription rate according to
the variables evaluated are shown in Table 4.
MPR, rate of AMA, and its related factors
Of the subjects who received an antihypertensive
prescription, the subjects who purchased
antihypertensive medication were 24,449 (98.3%). Among them,
the MPR was 70.9%, the rate of AMA was 60.6%, and
the MPR and rate of AMA by the variables evaluated
are shown in Table 5. Based on the results of
multivariate logistic regression analysis, the variables
significantly associated with AMA were gender, age,
family history of hypertension, smoking status, BMI,
hypertension status, and the time of the first visit to
a medical institution. The OR and 95% CI for the rate of
AMA according to the variables evaluated are shown in
Table 6.
Discussion
This study was performed to assess the antihypertensive
medication adherence in patients who were newly
diagnosed with hypertension by the 2012 GHS
conducted by the NHIS on commencement of
pharmacological treatment and sustainability of antihypertensive
medication adherence using the followings indices: rate
of visiting a medical institution within 1 year after the
Table 2 Factors associated with visits to medical institutions
according to multiple logistic regression analysis
Family history of
hypertension
Smoking status
30–39 years
40–49 years
50–59 years
60–69 years
≥70 year
Insurance type
More than 3 times
Employment-based
Extremely obese
Hypertension level
Hypertension stage 1 1
Blood glucose level Normal
Hypertension stage 2 1.86
Blood LDL level
aOR odds ratio, bCI confidence interval
date of the second-step confirmatory test,
antihypertensive prescription rate within 1 year after the first visit,
MPR, and rate of AMA.
For effective management of hypertension, it is
imperative to receive an early diagnosis and to visit
a medical institution for pharmacological treatment
as well as nonpharmacological management by a
physician.
First, the rate of visiting a medical institution by the
study subjects diagnosed with hypertension was 42.3% in
Family history of
hypertension
Smoking status
Drinking frequency
(per week)
Insurance type
Hypertension level
Blood glucose level
Blood LDL level
30–39 years
40–49 years
50–59 years
60–69 years
≥70 year
More than 3 times
Employment-based
Extremely obese
Hypertension stage 1
Hypertension stage 2
Data are expressed as the number (%)
P-value from chi-square test for binary outcomes comparing a difference between of not receiving prescription and receiving prescription
this study. In addition, the rate of visiting a medical
institution was 20.9% for study subjects in their 30s.
These results could be interpreted as the early finding of
chronic disease such as hypertension by GHS did not
induce the early treatment effectively. These results were
related with the fact that the rates of awareness and
treatment for hypertension in the 30s in Korea were 19.1
and 12.4% [18]. In order to manage hypertension and
prevent its complications, first of all, there is a need to
alert those with risk factors for hypertension and those
diagnosed but who not visit a medical institution to
improve the awareness rate. In addition, the rate of visiting a
medical institution within 1 year of diagnosis was higher in
women than men, those of advance age, those with a family
history of hypertension, ex-smokers, those with a high
BMI, those with more severe hypertension, or those with
other chronic diseases, such as diabetes or hyperlipidemia.
Next, among subjects who visited a medical institution,
89.1% received the antihypertensive prescription by a
physician. The antihypertensive prescription rate was low
Table 4 Factors associated with antihypertensive prescription
according to multiple logistic regression analysis
Family history of
hypertension
Smoking status
Drinking frequency
(per week)
Insurance type
Hypertension level
Blood glucose level
Blood LDL level
30–39 years
40–49 years
50–59 years
60–69 years
≥70 year
More than 3 times
Employment-based
Extremely obese
Hypertension stage 1
Hypertension stage 2
aOR odds ratio, bCI confidence interval
among relatively healthy subjects, i.e., those in their 30s
with no family history of hypertension, and those with a
normal BMI. The guidelines of JNC-8 and European
Society of Hypertension address treatment according to
hypertension level and risk factors [19, 20]. Lifestyle
changes are primarily recommended for those in low- or
medium-risk groups. Based on these guidelines, physicians
often recommended lifestyle changes instead of
antihypertensive medication for subjects who were relatively healthy
and belong to the low-risk group.
Finally, among subjects who received the antihypertensive
prescription, 98.3% purchased antihypertensive medication.
Among them, the MPR was 70.9% and the rate of AMA
was 60.6%. Medication adherence of women (62.5%) was
better than that of men (58.4%), that of advanced age (≥70:
59.9%), that with a relevant family history, that with a high
BMI, that with high blood pressure, and that with a delayed
first visit to a medical institution. There were some studies
about medication adherence for hypertension. For example,
Rolnick et al. revealed that medication adherence was
better in men (70.5%) than in women (68.8%), those of
advanced age (≥70: 70.5%) in the U.S, [10]. Yang et al.
reported that medication adherence was 43.5% and better in
men (47.2%) than in women (40.3%), those of advanced age
(≥70: 55.6%), those with having a knowledge about
hypertension needs lifelong medical treatment (47.1%) in Beijing
[11]. And Inkster et al. found that medication adherence
was better in men (87%) than in women (85%), those of a
advanced age (≥70: 91%), those with high comorbidities (2
+: 91%) in the UK [12]. Lee et al. showed that
approximately 53% of the patients had high compliance with
antihypertensive medication in Taiwan [13]. Since each study
and disease has its own definitions of the evaluation
methods, medication adherence, and follow-up periods for
medication adherence, it is not easy to compare the results
directly among studies. Nevertheless, the MPR for
hypertension treatment in this study was higher than that of
Taiwan but lower than those of western countries.
Meanwhile, age and comorbidity were known as an important
factors related to expectations regarding treatment, and
attitude to taking medication [21, 22]. Similarly, the rates of
visiting a medical institution and of AMA were low among
younger subjects and some subgroups, such as subjects
who were overweight or had higher LDL-cholesterol levels,
had higher rates of AMA in this study. The rate of
medication adherence was also high when the satisfaction rate
regarding medication counseling was high [23], while
“forgetting to take the medication” was the principal reason
for decreased medication adherence [24]. According to a
previous systematic review study regarding the MPR and
the rate of AMA for chronic diseases [25], 12-month MPR
was 67% and the rate of AMA was 64% in hypertension,
MPR was 76% and the rate of AMA was 58% in diabetes,
and MPR was 74% and the rate of AMA was 51% in
dyslipidemia. To improve medication adherence, it is
necessary for a physician to promote and educate hypertension
patients themselves to recognize the importance of
medication treatment, and to provide appropriate counseling
services them to change the health behaviors like smoking,
physical activities etc.
This study had several limitations. First, as the data
from GHS and health insurance claims were used, this
study had the limitation of using secondary data.
Therefore, we could not examine the characteristics of the
Family history of
hypertension
Smoking status
Drinking frequency
(per week)
Insurance type
Hypertension level
Blood glucose level
Blood LDL level
Time of the first visit to a
medical institution (days)
40–49 years
50–59 years
More than 3 times
Employment-based
Extremely obese
Hypertension stage 1
Hypertension stage 2
1,259 (35.0)
4,415 (37.5)
2,336 (65.0)
7,358 (62.5)
Medication possession ratio's data are expressed as the mean (SD)
Appropriate medication adherence’s data are expressed as the number (%)
P-value from chi-square test for binary outcomes comparing a difference between of MPR ≥ 80% and MPR < 80%
study population, such as knowledge, attitude, or access
to medical institutions, etc. Second, this study dealt only
with a study population with primary or secondary
disease codes for hypertension. Therefore, it is likely that
some data were missing, because they were not claimed
as primary or secondary disease codes. However, the
chance of this was very low because the study
population was diagnosed with hypertension for the first time
through GHS in 2012. Third, medication adherence was
determined as the MPR based on the purchase of
antihypertension medication that was prescribed by a physician.
MPR cannot be used to verify the intake of the
Table 6 Factors associated with the appropriate medication
adherence according to multiple logistic regression analysis
Appropriate medication
adherence
ORa 95% CIb
Family history
of hypertension
Smoking status
Drinking frequency
(per week)
Insurance type
30–39 years
40–49 years
50–59 years
60–69 years
≥70 year
More than 3 times
Employment-based
Extremely obese
Blood pressure level Hypertension stage 1 1
Blood glucose level Normal
Hypertension stage 2 1.24
Blood LDL level
Time of the first
visit to a medical
institution (days)
medication compliance, we used the purchase of
antihypertension medication that is the next step after receiving
the antihypertensive prescription. Of the subjects who
received an antihypertensive prescription, the rate of the
purchase of antihypertensive medication was 98.3% in this
study. MPR and the rate of AMA based on the prescription
were 69.9 and 59.7% (not described in the result) but those
of based on the purchase were 70.9 and 60.6%. We could
find there was the difference values of MPR and the rate of
AMA between the data. In fact, patients who purchased
the medication take more positive behavior on treatment
than patients who were just prescribed medication.
This study showed that the antihypertensive medication
adherence in patients who were newly diagnosed with
hypertension was not relatively high in Korea. First of all,
those diagnosed with hypertension should visit a medical
institution to increase the MPR and rate of AMA. Medical
institutions that diagnose hypertension should notify and
educate hypertensive patients of their medical situation
and encourage them to participate actively in treatment.
Next, those diagnosed with hypertension should follow
the directions of their physicians and cooperate to manage
their hypertension. NHIS should make and support an
environment in which medical institutions and those
diagnosed with hypertension can fulfill their roles.
Acknowledgements
This work was supported by Konkuk University in 2014.
Authors’ contributions
HJ mainly wrote the manuscript; HK contributed to conception and design
of study, acquisition of data and interpretation of data. JHL, HMA and VK
conducted data clearing and data analysis. KL and SAS provided the
statistical support contributed to the interpretation of study results. All
authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Ethics approval and consent to participate
This article does not contain any studies with human participants performed
by any of the authors. This study was reviewed and approved by the
Institutional Review Board of Konkuk University Hospital (KUH1260021).
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
aOR odds ratio, bCI confidence interval
medications. However, the prescription is significant as
the first step in taking a medication, and there have been
reports that the MPR that use the prescription is a good
index for verifying medication adherence [26].
Furthermore, it is almost impossible to verify medication
compliance in studies based on massive databases. In order to
overcome the limitation of prescription that can not verify
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