Evaluating Demographic Surveillance

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Evaluating Demographic Surveillance

• Adult Mortality

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Contents

• Demographic Surveillance
• INDEPTH Network
• Mortality measures from DS
• Advantages/Disadvantages of DS
• Remedies for disadvantages ?
• Contributions of DS to knowledge of mortality in
  DW
• Example Gwembe
• Example Agincourt

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Demographic Surveillance

• Set of field and computing operations
• Longitudinal, prospective monitoring
• Monitor various entities that are resident in a
  well-defined geographic area
• People
• Households
• Residential locations
• ...
• At minimum describe vital events and migration
• Most DS sites also monitor a wide variety of
  other things
• SES, medical trials, etc.

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INDEPTH Network

• An International Network of Field Sites with
  Continuous Demographic Evaluation of Populations
  and Their Health in Developing Countries
• www.indepth-network.org
• Brings together DS sites under one umbrella
• Encourages best practices
• Conducts multi-site analysis of existing data
• Working on developing multi-site investigations
• Primary product so far, monograph on mortality
• INDEPTH Network. 2002. Population, Health and
  Survival at INDEPTH Sites, vol. 1, Population and
  Health in Developing Countries. Ottawa, Canada
  International Development Research Centre.

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Mortality Measures from DS

• Age-specific mortality rates, hazards of death
• Infant, child, neonatal, perinatal and maternal
  mortality rates
• Cause of death through verbal autopsies
• Wide variety of explanatory variables available
• SES measures
• Time (historical period)
• Household relationships
• Environmental factors
• Food security

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Advantages of DS

• Describe populations not described by other data
  particularly in sub-Saharan Africa
• Individual-based, prospective, fully linked data
  that describe a whole population at several
  levels
• Longitudinal record history of populations, some
  for reasonably long periods 40 years

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Disadvantages of DS

• Representativity
• The most often cited fatal problem
• True, but not a fatal problem especially since
  most DS sites are not designed as mortality
  monitoring systems, rather as population
  laboratories in which to test prevention and
  treatment initiatives
• Cost
• High but modest in comparison to a fully
  functioning vital registration system, it if were
  to exist in areas where DS sites are located
• Accessibility
• This is the potentially fatal problem

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Issues with Accessibility

• Why is it so hard to access DS data?
• Possessiveness on the part of DS sites
• Small projects with very limited funds
• Severely overworked scientists and administrators
• Not enough time to analyze their data in full
• Leads to possessiveness and suspicion that
  outside users will rip off the data without
  giving site adequate credit
• Complicated temporal structure of relational
  databases that typically manage DS data
• DS databases are complex
• Insufficient manpower and skills to extract data
  from DS DB

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Potential Remedies (1)

• Representativity
• Combine DSS with sample vital registration (SVR)
  to produce hybrid system that retains the
  benefits of both
• SVR is representative of a large geo-political
  area but very shallow in terms of data it
  collects
• Thoughtfully positioned DS sites within larger
  SVR area can deepen the description of portions
  of the SVR area
• Cost
• Also addressed through combination with SVR
  spreads the cost of the DSS over a much larger
  area and provides more insightful backstop for
  the SVR system

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Potential Remedies (2)

• Permission to use DS data
• Possessiveness of sites not likely to change
  without significant reorganization of conduct and
  funding of DS
• More human resources needed to allow DS sites to
  adequately analyze their own data in timely
  fashion
• Funders need to address issues of data access,
  data sharing etc.
• Logical access
• DS databases need to be redesigned with a
  thoughtful, standardized data warehouse
• Population scientists need more training in
  modern data management techniques
• INDEPTH is currently addressing both of these DB
  issues

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Contributions of DS to Knowledge of Adult Mx

• Substantial and rapidly increasing volume of
  literature describing various aspects of
  mortality at DS sites
• Over the past 3 years 10 articles/year on
  mortality from 20 DS sites that have been
  operating over that time
• INDEPTH monograph on mortality
• Detailed description of DS and contributing DS
  sites
• 19 sites contributed, all except Matlab from
  Africa
• 6.4 million person years of exposure
• Sex-specific life tables from each site
• Basic descriptions of levels of mortality at each
  site
• Identified seven commonly observed age patterns
  of mortality

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Crude Death Rates and Expectation of Life at
Birth
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Example Gwembe

• Collected by anthropologists as genealogies
• Gwembe District, Southern Zambia
• Period 1957-1995
• DOB, DOD, DOU, DOS, spouse parent-child links
• Dates with YEAR precision

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Trend in e0
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Percent Change in Male Mortality
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Percent Change in Female Mortality
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Example Agincourt

• Agincourt Health and Population Research Unit
• School of Public Health, University of the
  Witwatersrand, South Africa
• Demographic Surveillance System (DSS) with annual
  updates
• Period1992 ? present (4,756 deaths, 730,277 PYs)
• Vital statistics, link to mother and much more
• 21 Villages, Northeast South Africa
• 2003 study population of 72,000 in 11,550
  householdsDates with DAY precision

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Trend in 45q15 at Agincourt