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About the data

2.21

Definitions

The limited availability of data on health status is a

many developing countries most new infections

• Prevalence of smoking is the adjusted and age-

major constraint in assessing the health situation in

occur in young adults, with young women especially

standardized prevalence estimate of smoking among

developing countries. Surveillance data are lacking

vulnerable.

adults. The age range varies but in most countries is

for many major public health concerns. Estimates

Data on HIV are from the Joint United Nations

18 and older or 15 and older. • Incidence of tuber-

of prevalence and incidence are available for some

Programme on HIV/AIDS (UNAIDS) Global Report:

culosis is the number of new and relapse cases of

diseases but are often unreliable and incomplete.

UNAIDS Report Global AIDS Epidemic 2010. Changes

tuberculosis (all types) per 100,000 people. • Preva-

National health authorities differ widely in capacity

in procedures and assumptions for estimating the

lence of diabetes refers to the percentage of people

and willingness to collect or report information. To

data and better coordination with countries have

ages 20–79 who have type 1 or type 2 diabetes.

compensate for this and improve reliability and inter-

resulted in improved estimates of HIV and AIDS. For

• Prevalence of HIV is the percentage of people who

national comparability, the World Health Organiza-

example, improved software was used to model the

are infected with HIV. Total and youth rates are per-

tion (WHO) prepares estimates in accordance with

course of HIV epidemics and their impacts, making

centages of the relevant age group. Female rate is as

epidemiological models and statistical standards.

full use of information on HIV prevalence trends from

a percentage of the total population living with HIV.

Smoking is the most common form of tobacco use

surveillance data as well as survey data. The soft-

• Condom use is the percentage of the population

and the prevalence of smoking is therefore a good

ware explicitly includes the effect of antiretroviral

ages 15–24 who used a condom at last intercourse

measure of the tobacco epidemic (Corrao and others

therapy (ART) when calculating HIV incidence and

in the last 12 months.

2000). Tobacco use causes heart and other vascular

models reducted infectivity among people receiv-

diseases and cancers of the lung and other organs.

ing ART, which is having an increasing impact on

Given the long delay between starting to smoke and

HIV prevalence, with HIV-positive people living lon-

the onset of disease, the health impact of smoking

ger lives. The software also allows for changes in

in developing countries will increase rapidly only in

urbanization over time—important because preva-

the next few decades. Because the data present a

lence is higher in urban areas and because many

one-time estimate, with no information on intensity

countries have seen rapid urbanization over the past

or duration of smoking, and because the definition of

two decades.

adult varies, the data should be used with caution.

The estimates include plausible bounds, not shown

Tuberculosis is one of the main causes of adult

in the table, which reflect the certainty associated

deaths from a single infectious agent in develop-

with each of the estimates. The bounds are avail-

ing countries. In developed countries tuberculosis

able at http://data.worldbank.org or from the original

has reemerged largely as a result of cases among

source.

immigrants. Since tuberculosis incidence cannot

Data on condom use are from household surveys

be directly measured, estimates are obtained by

and refer to condom use at last intercourse. How-

eliciting expert opinion or are derived from mea-

ever, condoms are not as effective at preventing the

surements of prevalence or mortality. These esti-

transmission of HIV unless used consistently. Some

mates include uncertainty intervals, which are not

surveys have asked directly about consistent use,

shown in the table, which are available at http://

but the question is subject to recall and other biases.

data.worldbank.org or from the original source.

Caution should be used in interpreting the data.

Diabetes, an important cause of ill health and a

For indicators from household surveys, the year in

risk factor for other diseases in developed countries,

the table refers to the survey year. For more informa-

is spreading rapidly in developing countries. Highest

tion, consult the original sources.

among the elderly, prevalence rates are rising among younger and productive populations in developing

Data sources

countries. Economic development has led to the

Data on smoking are from the WHO’s Report on

spread of Western lifestyles and diet to develop-

the Global Tobacco Epidemic 2009: Implementing

ing countries, resulting in a substantial increase in

Smoke-Free Environments. Data on tuberculosis

diabetes. Without effective prevention and control

are from the WHO’s Global Tuberculosis Control

programs, diabetes will likely continue to increase.

Report 2010. Data on diabetes are from the Inter-

Data are estimated based on sample surveys.

national Diabetes Federation’s Diabetes Atlas,

Adult HIV prevalence rates reflect the rate of HIV

3rd edition. Data on prevalence of HIV are from

infection in each country’s population. Low national

UNAIDS’s Global Report: UNAIDS Report on the

prevalence rates can be misleading, however. They

Global AIDS Epidemic 2010. Data on condom use

often disguise epidemics that are initially concen-

are from Demographic and Health Surveys by

trated in certain localities or population groups and

Macro International.

threaten to spill over into the wider population. In

2011 World Development Indicators

117

people

Health risk factors and future challenges

World Development Indicators 2011 Part 1 of 2  

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