Demographic Surveillance Systems (DSS)
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Surveillance involves actively following populations to detect births and deaths.
There are four main approaches:
- Demographic Surveillance Systems (DSS )
- Prospective studies
- SAVVY
- Sample Vital Registration Systems
Demographic Surveillance Systems (DSS) began in the 1960s as a means of tracking longitudinal demographic changes to populations in developing countries. Unlike prospective (cohort) studies, DSS are able to monitor entire populations and are usually larger and longer term. Field sites collect data on births, deaths (including causes) and migration which provide an important resource for evaluating health care interventions. They also offer a starting point for new studies. The INDEPTH Network (“An International Network for the Continuous Demographic Evaluation of Populations and Their Health in Developing Countries”), is an international network of 31 DSS field sites in 17 countries spanning Africa and Asia.
Identification of death:
Enumerators make initial census/count of population. Subsequently, an adult family member reports household deaths since the last update round (ranging from every two weeks to annual rounds). Enumerators probe on all births (pregnancies), deaths, and migrations.
Ascertainment of maternal/pregnancy related status
- Adult responds to Pregnancy-related questions; or
- Appropriate respondent gives cause of death (from health facility, death certificate, or Verbal Autopsy); or
- Birth-Death Linkage is used to identify pregnancy related deaths
Advantages:
- useful for monitoring and evaluation of public health interventions
- more complete enumeration of vital events than available from Civil Registration in most countries with weak infrastructure
- provide comparable data over time for analysis of trends
- researchers associated with the DSS are on-site for data analysis
Limitations:
- data from DSS field sites may not be generalisable to regional or national populations
- costly and research intensive
- covers relatively small populations
- women who leave the surveillance area to deliver and subsequently die outside the area may be missed, as might women who migrate into the surveillance area to deliver
Measurement requirements:
- if verbal autopsy questions are used they must be coded and classified as maternal deaths
- data on births are needed to calculate the maternal mortality ratio (MMR)
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INDEPTH Resource Kit for Demographic Surveillance Systems (Beta Version 0.9) |
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Baiden, F; Hodgson, A; Binka FN (2006) Demographic surveillance sites and emerging challenges in international health. Bulletin of the World Health Organization, 84(3): 163-4. |
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Ngom, P; Binka FN; Phillips, JF; Pence, B; Macleod, B (2001) Demographic surveillance and health equity in sub-Saharan Africa. Health Policy and Planning, 16(4): 337-44. |
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Tatem, A.J; Snow, R.W.; Hay, S.I. (2006) Mapping the environmental coverage of the INDEPTH demographic surveillance system network in rural Africa. Tropical Medicine & International Health, 11(8):1318-26. |
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INDEPTH Network: An International Network for the Continuous Demographic Evaluation of Populations and Their Health in Developing Countries: http://www.indepth-network.org |
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INDEPTH Network (2002) Population and health in developing countries: Volume1: Population, health and survival at INDEPTH sites. Ottawa: International Development Research Centre. |