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Diagnosis and control of hypertension in the elderly populations of Japan and the United States

experienced hypertension were then asked if they used medication for the condition.
Overall hypertension is indicated by either having measured hypertension or using medi-
cation. Table 1 presents descriptive measures on the sample and for the hypertension
measures.
By utilizing measured hypertension and diagnosed hypertension, we are able to divide
the total population into four hypertension categories: healthy, undiagnosed hypertension,
controlled hypertension, and uncontrolled hypertension. Healthy was defined as not having
measured hypertension and reporting that one has never been diagnosed with or expe-
rienced hypertension. Undiagnosed hypertension was defined as having measured hyper-
tension but reporting that one has never been diagnosed with or experienced hypertension.
Uncontrolled hypertension was defined as having measured hypertension and reporting
hypertension. Controlled hypertension was defined as having been diagnosed with or ex-
periencing hypertension and having measured systolic blood pressure of less than 140
mmHg and diastolic blood pressure of less than 90 mmHg.

2.3 Statistical Methods
All analyses were weighted and conducted on Statistical Analysis System (SAS) 9·2 (SAS
Institute Inc. Cary, NC). To account for missing data on measured blood pressure, an ad-
justed weight was created for NUJLSOA by multiplying the normalized weight of the
sample which accounted for the lack of survey response and differential selection by age
by the inverse of the predicted probability that each participant would have a blood pres-
sure measurement. The predicted probability was based on age, sex, and level of education.
It was used in all analyses. For the HRS, sample weights which accounted for survey
non-response, nonresponse to the blood pressure measurement, and initial proability of
selection were provided by the survey and were used for all analyses.

3. Results
3.1 Descriptive Results

Table 1 indicates that Japanese over age 68 are almost twice as likely as their American
counterparts to be measured as hypertensive (74.3% versus 39.5%). By contrast, Japanese
persons are significantly less likely to report that they have been diagnosed with hyperten-
sion (37.9% in Japan vs 64.1% in the U.S.). Older Japanese are also much less likely to
use antihypertensive medication than their American counterparts (36.0% vs 59.7%). The
overall prevalence of hypertension, which includes either measured hypertension or use of
medication, is also significantly higher in Japan than in the U.S. (82.0% vs 74.1%).
We then integrated self-reports and measured levels to examine the prevalence of diag-
nosis and control. We find that there are much higher rates of undiagnosed hypertension in
Japan (44.3%) than in the U.S. (11.9%) for this older age group (Table 2). In addition, the

Table 1. Measured, self-reported hypertension, use of hypertensives, overall hypertension by country
Japan United States
Percent of total sample Percent of total sample
Measured Hypertension 74.3 (72.5–76.1) 39.5 (37.8–41.1)
Self-Reported Hypertension 37.9 (35.3–40.0) 64.1 (62.5–65.7)
Use of Antihypertensives 36.0 (34.0–38.0) 59.7 (58.1–61.4)
Overall Hypertension 82.0 (80.4–83.6) 74.1 (72.6–75.5)
n 2309 3517

International Journal of Population Studies | 2015, Volume 1, Issue 1 22