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Yasuhiko Saito, Shieva Davarian, Atsuhiko Takahashi, Edward Schneider and Eileen M. Crimmins

sure was measured as part of a home interview; while both the survey of circulatory dis-
orders and the NHNS required measurement at a site away from home. The need to leave
home in order to be included in a study is one cause of underrepresentation of the oldest
and most frail; only 7.0% of the NHNS sample was 85 years or older and only 1.4% was
90 years or older, compared to 11.9% and 3.3% in the NUJLSOA. On the other hand,
younger people are more represented in the NHNS, 18.1% of the sample persons aged 68
and older is 68 and 69 years of age, whereas only 12.6 % of the NUJLSOA is in these two
ages. People who are sicker and frailer are also less represented in the NHNS. The pro-
portion of the sample aged 68 and older with a lot of difficulty in performing activities of
daily living is almost twice as high as (1.81 times) in the NUJLSOA. Because the NUJL-
SOA is an ongoing longitudinal study, sicker people are more likely to continue to partici-
pate than if they were being newly recruited to a study. In addition, measurement at
home, as is done in the NUJLSOA, could raise measured blood pressure because of a “re-
verse white coat” syndrome. Blood pressure measurement at home has been reported to
exceed measurement in clinics in Japan (Liu, Roman, Pini et al., 1999; Selenta, Hogan and

Linden, 2000; Wing, Brown and Beilin, 2002). Comparison of home versus clinic mea-
surement in one Japanese study among hypertensives indicated an increase of 12% in
those measured as uncontrolled at home (Obara, Ohkubo, Funahashi et al., 2005). Because
both the Japanese study and the U.S. study were conducted at home with similar instru-
ments and because both are weighted to represent the population aged 68 and older, they
should be comparable in measured hypertension; however, the differential timing of the
blood pressure measurement in the two studies could have potentially resulted in a relative
increase in Japanese blood pressure.
The lack of hypertension diagnosis and lack of hypertension control is unlikely to be
explained by a lack of contact with the medical system in either Japan or the U.S. Japan is
a country where the population has very high medical contacts. The average reported
number of physician visits in the year prior to survey for this Japanese sample was 20.9
and this does not vary much by hypertensive state. Even the undiagnosed and the uncon-
trolled hypertensives average 21 and 20 doctor visits in the past year, respectively. Older
Americans in the HRS reported many fewer doctor visits, e.g., who were over age 68 re-
ported an average of 5.5 visits in the year prior to survey, those with undiagnosed hyper-
tension having 3.5 visits and those with uncontrolled hypertension having 5.3 visits. There
are few people in both countries who reported not seeing a physician at all in the year prior
to survey. In Japan, no one reported not having had a doctor’s visit in the year prior to
survey, whereas this was true of only 7.1% of the Americans. However, this value was
higher among Americans with undiagnosed hypertension, 17.4%. Thus, it does not appear
that medical exposure is responsible for the lack of hypertension diagnosis or control in
Japan; instead it could be a factor in the lack of diagnosis in the U.S.
The high frequency of medical visits in Japan is in part due to the practice of providing
prescriptions for short time periods. In 2006, most drugs could only be prescribed for a
thirty-day period and selected drugs for only a fourteen-day period in Japan. Renewing a
prescription required another doctor visit. By contrast, prescriptions can be renewed for 3
months or even longer time periods in the U.S. and renewal can also be done by phone.
This practice of required physician visits could also result in patients in Japan being more
likely to be non-compliant with anti-hypertensive medication regimens.
An explanation for why more people might remain undiagnosed in Japan than the U.S.
is that some specialists in Japan do not routinely measure blood pressure as part of a doc-
tor visit. For instance, departments in hospitals for treatment of eyes, ears, and orthopedics,
do not routinely perform blood pressure measurement in Japan. A second potential expla-
nation for differences in hypertension control is the difference in the pattern of prescribed

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