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Ifakara Centre Demographic Surveillance System (IC-DSS)

Introduction

The Ifakara Centre Demographic Surveillance System (IC-DSS) is a new unit within IHRDC. The unit operates a demographic surveillance system in a defined geographical area of 25 villages in Kilombero and Ulanga Districts, ensuring that all residents of the area are registered and that all births, deaths and in and out migrations are recorded on a regular basis (see map).

IC-DSS provides accurate information on population, fertility and mortality in a rural Tanzanian population of approximately 65,000 people. This information is used by health planners to optimise the use of scarce resources for health care. The system also provides a framework for research studies: for example, studies of average household income, or of resistance to existing antimalarial drugs.

IC-DSS started in 1996 as part of the KINET project, where it provided a framework for the evaluation of a malaria control program. Within the DSS, the effects of socially-marketed insecticide-treated nets on maternal and child health and survival were studied. Results from these studies have helped to secure funding for nets and insecticide for 2000-2002.

  Goals of the Unit

1.    To document all births, deaths, and migrations into and out of the IC-DSS area
2.    To summarise this information and share it with the communities themselves and their leaders
3.    To work towards systematic use of such information for better health in Kilombero and Ulanga Districts, Morogoro Region, and at national    level
4.    To provide a framework for population-based health research which is relevant to local health priorities and needs
5.    To facilitate relevant population-based health research for collaborators within and external to IHRDC
6.    To ensure feedback of  research results to families in the IC-DSS area

  Map: Kilombero and Ulanga Districts, showing the DSS area (shaded)

Methods

A baseline census was carried out from September to December 1996, during which all households and residents were registered into the DSS system. Since January 1997, every registered household has been visited every four months by an interviewer. During the interview an adult household member is asked about demographic events such as pregnancies, births, deaths, in and out migrations within the household. All information is recorded in the “household record book” or HRB and on forms which record each type of event. HRBs are bound into bundles of approximately 50 households which are close to each other. Interviewers report their work on a weekly basis to a supervisor, who brings the completed work to a weekly field meeting in Ifakara. All household visits and events are recorded in a database system. Any inconsistencies which cannot be resolved from the forms are sent back to the field team for correction. Any new households within the area - for example, when children leave home and become independent from their parents - are recorded as soon as possible.

The four month field work cycle starts every January, May and September and involves a week of training, then 14 weeks of field work, then one week of holiday and lastly one week of resolving queries in the field which have arisen from the work of the previous four months. The households to be visited each week are allocated according to a strict schedule to try to ensure visits are exactly four months apart.

Methods

A baseline census was carried out from September to December 1996, during which all households and residents were registered into the DSS system. Since January 1997, every registered household has been visited every four months by an interviewer. During the interview an adult household member is asked about demographic events such as pregnancies, births, deaths, in and out migrations within the household. All information is recorded in the “household record book” or HRB and on forms which record each type of event. HRBs are bound into bundles of approximately 50 households which are close to each other. Interviewers report their work on a weekly basis to a supervisor, who brings the completed work to a weekly field meeting in Ifakara. All household visits and events are recorded in a database system. Any inconsistencies which cannot be resolved from the forms are sent back to the field team for correction. Any new households within the area - for example, when children leave home and become independent from their parents - are recorded as soon as possible.

The four month field work cycle starts every January, May and September and involves a week of training, then 14 weeks of field work, then one week of holiday and lastly one week of resolving queries in the field which have arisen from the work of the previous four months. The households to be visited each week are allocated according to a strict schedule to try to ensure visits are exactly four months apart.

 Village Reporters (Key informants - watoa taarif a) - VR

Every kitongoji (sub-village) has a village reporter, who is paid a small sum of money for information on every birth or death he/she reports among households in his/her kitongoji. Village reporters are volunteers who are chosen by the village leaders. There are 104 such village reporters. All births/deaths (events) are verified by a VR supervisor, who also checks whether the event has already been recorded in the HRB. If not, and the event has happened since the last visit to the household, she/he notes the event in the household record book in blue pen ready to be checked at the next four-monthly interview. If the event happened before the last recorded visit to the household, the query is resolved by the field team with a further visit to the household if necessary.

  Bereavement interviews

From September 2000 a group of specially-trained VR supervisors will try to elicit information on the cause of all deaths. They will interview bereaved relatives 14 to 30 days after the death (to be checked with Rufiji DSS, and the same time interval to be used). The interview will follow a structured questionnaire about the circumstances of the death, the signs and symptoms in the illness leading to the death, and the action taken. This information will be coded in Ifakara to give likely causes of death in broad categories. Initially this coding will be done by physicians, and later according to a standard algorithm.

  Quality control

Supervisors re-visit a randomly-selected 10% of households reported to have been visited in the previous week. This visit is in order to check that the interview did in fact take place, and to repeat the interview. Supervisors do not take the original HRBs with them during re-interviews, and deliberate random errors are inserted in household information which they take with them. The information collected is used to check for consistency with the original interview: any discrepancies are resolved by discussion between the supervisor and interviewer, with a revisit to the household if necessary. The random errors should be corrected: where they are not, the issue is discussed between the supervisor and the assistant field manager.

Supervisors also carry out 2-3 accompanied interviews with each of their interviewers every week, on a convenience sample basis.  Any problems noted are discussed and resolved immediately with the interviewers. Any discrepancies between information from the village reporters and that from the interviewers is resolved, no more than 4 months after the discrepancy occurs. 

The assistant field managers and field managers carry out surprise (i.e. unannounced) visits to the interviewers and supervisors. On average there is one such visit to each person during each round. During these visits they carry out accompanied interviews and at each household visited they check that all neighbouring households have been registered.

Geographical area covered

Of the 25 villages included in the system, 12 are in Ulanga District and 13 in Kilombero District. All are in the flood plain of the Kilombero River. Households are widely scattered and population density is low. Most people living in the area are subsistence farmers, growing rice, maize and cassava, and most families have a shamba house where some household members live for at least part of the year. The interviewers do their work at the shamba house or the village house, depending on where they can find a family member.

In 2001 all houses in the area will be mapped using a hand-held global positioning system (GPS). Detailed maps will be used to assess disease patterns and causes, and the information will be shared with local authorities.

  Annual surveys

Two special surveys are carried out once each year. In the first round of each year, educational level is updated as completed years of full-time education, or equivalent for part-time study. In the third round of each year, socio-economic status is assessed for every household through a list of household assets.

  Mapping

Every household in the DSS area will be mapped in 2001. As these maps become available, they will be shared with the field team and the village leaders.

Outputs

·         Annual population data for each Kitongoji, village, ward and division, by age and sex.
·         Maps showing roads, rivers, contours, and health facilities
·         Maps showing households, roads, rivers, contours, and health facilities (from April 2001)

For each district:

·         Mortality – deaths per month
·         Mortality rates by age and sex
·         Fertility rates by age
·         Cause-specific mortality (from 2001) by age and sex

  Organisation and Management

Figure 1 shows the weekly work cycle during each round: approximately 50 households are visited each week by every interviewer. Pregnancies, births, deaths, in and out migrations are recorded as “events” on the HRB and on special event forms. At the end of the week, completed forms and HRBs are checked by a supervisor and returned to Ifakara for data entry. The data entry is completed during the following week, and any queries arising from inconsistencies in the data are returned to the field for correction.

  The VR supervisors check events recorded by village reporters. Any events which have not already been recorded by the interviewers at a routine household visit are noted in blue pen into the HRB  by the VR supervisors. They are also recorded on forms which are returned to Ifakara for data entry. The VR supervisors interview bereaved relatives using the bereavement questionnaire. VR supervisors should carry out cause of death interviews on events reported by both systems.

  At the end of every round a check is made for any events reported by village reporters, which had not been identified by the interviewers. Where an event reported by the village reporters occurred after the routine household visit, no action is taken. Where an event reported by the village reporters occurred before the date of the routine household visit, field team resolves the discrepancy, with a further visit to the household if necessary.

Figure 1: flow of  work from field to data room and back

Meetings with the field team

Weekly meetings

·         Every interviewer meets his/her supervisor at least twice each week, once on Wednesday afternoon or Thursday morning, to collect the        work allocated for the next week, and once on Tuesday, to hand over work from the previous week.
·         Supervisors come to meet assistant field managers, the filing clerk, and field managers every Wednesday in Ifakara to report on progress,           discuss problems and collect supplies.
·         The assistant field managers, the filing clerk, field manager and data manager meet every Monday morning in Ifakara to review progress       and plan for the week.

Monthly meetings

·         On the first Friday in each month the field team all come to Ifakara, where they meet to discuss progress and problems with each other and        with the management team.
·         Village reporters each meet with their VR supervisors once each month.

Four-monthly meetings

·         At the beginning of each round (January, May, and September) the entire field team attends up to 5 days training in Ifakara.
·         Every round, village reporters get together in groups to meet with the VR supervisors and with assistant field managers or field managers, in       Kivukoni, Igota, Mbingu and Mchombe

Routines in the data room

Every week

·         Process HRBs from previous week
·         Update list of work received and that still to be done

Every month

·         Process events recorded by village reporters
·         Process bereavement interview forms and run consistency checking program

Every round

·         Reconcile migrations in and out
·         Reconcile pregnancies with births
·         Validation

Each year in December/January

·         Print HRBs

Each year in May/June

·         Compute demographic rates and village populations

  Ethical Issues

The success of the DSS depends on the relationship built between the DSS team and the community. All information collected is viewed as confidential at all times, and all summary information must never reveal individual identities.

Funding Sources

Five donors are currently supporting IC-DSS: WHO/CAH, the Swiss Tropical Institute (STI), the Swiss National Science Foundation (SNSF), the Swiss Agency for Development and Co-operation (SDC) and USAID through the Centers for Disease Control (CDC).

Send mail to scharles@ifakara.mimcom.net with questions or comments about this web site.
Copyright © 2002 Ifakara Health Research and Development Centre