3:10 AM
Unknown
RESEARCH DESIGN AND METHODS
— Diabetes prevalence
data for adults (20 years of age) were
derived from studies meeting the following
criteria: a defined, population-based
sample and diagnosis of diabetes based on
optimal WHO criteria (a venous plasma
glucose concentration of 11.1 mmol/l
2 h after a 75-g glucose tolerance test).
The exceptions to the latter criterion were
the study in China, for which a test meal
was used (4), and the study in Tanzania
(5), in which fasting glucose alone gave a
higher prevalence of diabetes than a previous
study that used the optimal WHO
criteria.
Prevalence estimates for type 1 diabetes
for people 20 years of age for individual
countries were estimated from
available incidence data using methods
described in the International Diabetes
Federation (IDF) Diabetes Atlas 2000 (6).
Population-based data are not available
for type 2 diabetes in people20 years of
age, and this group has been excluded
from these estimates.
Age- and sex-specific estimates for diabetes
prevalence were extrapolated to
other countries using a combination of
criteria including geographical proximity,
ethnic, and socioeconomic similarities
applied by the authors with the advice
of the WHO regional officer and other
experts.
Table 1 shows the studies used
and the countries to which data were
extrapolated.
Surveys were generally performed on
middle-aged populations, and data are
more limited at younger and older ages.
Data on diabetes prevalence are usually
presented in broad age bands, which suggest
a biologically implausible step-like
increase in diabetes prevalence with increasing
age.
DISMOD II software (available
from http://www3.who.int/whosis)
was used to produce smoothed, agespecific
estimates of diabetes prevalence
from the available data from each study.
Further details on DISMOD II have been
published elsewhere (7). In summary,
age- and sex-specific diabetes prevalence
(derived from the studies listed in Table
1), remission (assumed to be zero), and
estimates of relative risk of mortality
among people with diabetes (see below)
were entered into models.
The model output
provides estimates of prevalence, incidence,
and mortality that are consistent
with one another (7).
Estimates of relative risk of all-cause
mortality among people with diabetes, by
age and sex, were derived from the limited
number of cohort studies that provide
this information (8–10). Estimated
relative risks for all-cause mortality
ranged between 1 (for the oldest agegroup,
80 years of age) and 4.1 (for
20–39 years of age) for men and between
1 (for 80 years of age) and 6.7 (for
20–39 years of age) for women.
Further
information on the estimation of agespecific
relative risks is available in the
draft Global Burden of Disease 2000 documentation
(11).
Mortality data were derived
from developed countries (U.K.,
Sweden, and U.S.). As no information was
available for developing countries, the
same relative risks were assumed to apply.
Data are required to test the validity
of this assumption. Survival is unlikely to
be better in developing countries than developed
countries, and any bias in the approach
we have taken would lead to
conservative estimates of incidence of diabetes
in developing countries but would
not affect estimates of prevalence.
Estimates
of incidence and mortality are
not presented in this report but are
available from the authors and from the
draft Global Burden of Disease 2000
documentation (11).
The prevalence estimates were applied
to population estimates for individual
countries for 2000 and 2030, which
were produced by the United Nations
Population Division (12).
Conventional,
albeit simplistic, definitions of developed
countries (Europe including former socialist
economies, North America, Japan,
Australia, and New Zealand) and less developed
countries (all other countries)
were used. In keeping with previous estimates,
prevalence of diabetes was assumed
to be similar in urban and rural
areas of developed countries (2).
For developing
countries, urbanization was
used as a proxy measure of the increased
risk of diabetes associated with altered
diet, obesity, decreased physical activity,
and other factors such as stress, which are
assumed to differ between urban and rural
populations. For most developing
countries, the prevalence of diabetes in
http://the-survey.blogspot.com/2011/09/health-survey-global-prevalence-of.html http://the-survey.blogspot.com/2011/09/health-survey-global-prevalence-of_9471.html
Posted in: 
0 comments:
Post a Comment