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7
Data Collection and Validation in Resource-
Poor Settings
Much of the input to the workshop emphasized the point that patterns of
morbidity and mortality are shifting both in terms of cause and in terms of age
distribution. The workshop paper by Byass, de Savigny, and Lopez notes that changing
therapeutic options tend to increase prevalence as compared with incidence for some key
diseases; perhaps the most obvious example of this phenomenon in sub-Saharan Africa
can be found in the use of antiretroviral therapy against HIV/AIDS, which keep AIDS
patients alive for longer periods of time, thus increasing rates of prevalence. Changing
patterns of risk factors--such as the prevalence of mosquito breeding sites in the case of
infectious diseases, or factors such as tobacco and alcohol consumption in the case of
noncommunicable diseases--constitute a further critical factor in the changing patterns of
mortality and morbidity (Dalal et al., 2011; Danaei et al., 2011). All of these factors are
changing rapidly against a background of sparse and sometimes dubious detailed
information about what is actually happening, which makes it even more vital to
proactively consider changes in health data systems in sub-Saharan Africa in order to
increase the visibility of the continent's long-term trends and needs in population health
(Byass, 2009).
Nevertheless, it is unrealistic to suppose that over the next 10 to 20 years all the
countries of sub-Saharan Africa will develop national health information systems that
have sufficiently high coverage and achieve global standards of timeliness, completeness,
and quality. Thus it is necessary to consider a transitional approach to improving the
supply of health information in the short term in ways that are relevant to the essential
policy actions that sub-Saharan African countries will need to take as the epidemiological
transition unfolds.
In his presentation for the session on data collection and validation, Peter Byass
identified several key questions that countries and international agencies should consider:
What mix of national and local-area data sources are needed for monitoring
epidemiological transition, and with what sampling approaches?
How can continuous longitudinal, repeated cross-sectional, and one-time
survey data be effectively integrated within a national information system to
reveal epidemiological transitions?
What are the economic and human resource implications for upgrading
national health information systems in order to measure epidemiological
transitions?
What are the ethical and political issues related to long-term improvements in
national health information systems?
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Byass, de Savigny, and Lopez also described a typology of data sources that can
potentially contribute to national health information (see Table 7-1).
TABLE 7-1 Typology of Data Sources That Potentially Contribute to National Health
Information
Level Model Sample Approach Examples
National National census All Complete cross- Most countries
section
Ongoing All Complete Industrialised
registration longitudinal countries
Sentinel districts 1-2% of Longitudinal China
population sample
Cluster surveys Cluster sample Repeatable DHS surveys,
size cross-section WHO-SAGE
Fixed panel Cohort sample Longitudinal Millennium
surveys size cohort Cohort Study
At health All or sample of Self-selected Annual health
facilities facilities group reports
Provincial Complete All Complete In registered
population longitudinal countries
Cluster surveys Cluster sample Cross-section Vaccine
size coverage
At health All or sample of Self-selected Annual health
facilities facilities group reports
Local area Individual Defined area Complete in INDEPTH
surveillance population defined area centers
One-time Survey sample Cross-sectional
surveys size
Specific Context- Specific issues
research dependent of interest
SOURCE: Byass, de Savigny, and Lopez (2011).
This session also included a discussion of how lessons learned to date from HIV
surveillance efforts might be applied. Thomas Rehle described the key features of
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second-generation HIV surveillance, which include (1) combining survey methods for
greater explanatory power; (2) developing strategic partnership between surveillance and
program evaluation; (3) a shift in emphasis toward measuring incidence rather than
focusing mainly on prevalence; and (4) recognition of biological (HIV, AIDS, sexually
transmitted infections) and behavioral surveillance as integral components adapted to the
stage and type of the epidemic. These features imply a surveillance that is more focused
on subpopulations at high risk of infection and that has an emphasis on trends over time.
Rehle further described the new South African National Health and Nutrition
Examination Survey (SANHANES). It combines questionnaires with physical
examinations and biomarker testing, combines longitudinal and cross-sectional design
elements, and is designed to make it possible for health and nutritional status to be
explored in much greater detail than was previously possible.
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