Health and Demographic Surveillance System (HDSS) in Matlab, Bangladesh

International Centre for Diarrhoeal Disease Research, Bangladesh, (icddr,b, former Pakistan SEATO Cholera Research Laboratory) set up a field diarrhoea hospital in Matlab in December 1963 for evaluating acceptability, safety and efficacy of cholera vaccines, including oral rehydration therapy, and studying the epidemiology, prevention and treatment of diarrhoeal diseases and other public health interventions. The evaluation studies required accurate count of population at risk for computing rates and ratios. Matlab HDSS (former DSS till 1999) was established in May 1966 for counting the de jure population and births, deaths and migrations with precise dates.1 High rates of fertility and mortality and poor availability and accessibility of primary health care in rural areas provoked design and implementation of a quasi-experimental maternal and child health and family planning (MCH-FP) programme in one half of the surveillance area, keeping the other half as comparison receiving usual government health services, with the aim to estimate the programme effects on fertility and mortality reductions, using HDSS data.2 Subsequently the MCH-FP programme, along with the HDSS, became a training site for programme planners and implementers from developing countries. The DSS was first set up in 132 villages with a population of 111 748 in May 1966, and expanded to the adjacent 101 villages in 1968, totalling 263 507 residents.1,3 In October 1977, the surveillance area was reduced from 233 to 149 villages with a population of 172 000 which was sufficient for implementation and evaluation of the MCH-FP programme in controlling high fertility and maternal and child mortality. In 1987 seven villages faced river erosion, leaving the DSS area with 142 villages till present, which are inhabited by 230 185 residents as of 30 June 2014. The MCH-FP programme introduced a record-keeping system (RKS) of maternal and child services that it has provided since 1978. RKS was extended to the comparison area in 2001. A geographical information system (GIS) of recording geo-locations of baris (a small clusters of households sharing common yard and whose heads are related to each other by blood), tube-wells, villages, health facilities, educational institutes, mosques, temples, rivers and roads in degree decimal format, was started in 1994. Both RKS and GIS in the HDSS area were under different administrative supervisions. These data generation systems were merged and named ‘HDSS’ and brought under one administrative supervision in 2000.4 A list of variables collected in HDSS records is given in Table 1. Variables collected during routine household visits in the Matlab HDSS area Household roster: Identification (village, bari, household and person) Name, age and sex of the member Education, occupation and marital status Membership of non-government organizations Household socioeconomic status: Water and sanitation condition Household possession of durable assets Sources of income and food security Registration of birth: Identification of baby, father and mother Pregnancy history of the mother Sex, date and place of birth Duration of pregnancy, multiple births pregnancy and antenatal care visits by trimester Registration of death: Identification of deceased Age, sex, date and place of death Verbal autopsy (open narratives, signs and symptoms that led to death; medical treatment and lifestyle) Registration of migration (in and out): Identification of migrant Age, sex and date of migration Education, occupation and marital status of migrant Place of origin or destination of migrant Reasons for migration Pregnancy history of ever married women of reproductive age Registration of marriage and divorce: Identification of partner(s) Age, sex, education and occupation of the partners Date of event and registration with legal department Previous marital status of the partners Transaction of marriage gift and dowry Reasons for divorce Registration of internal movement: Date of movement within the HDSS area Creation of new household and household split Cause of movement Registration of change in household head: Date of change Reason for change in headship Age and sex of new head Altered relationship with household members due to change MCH-FP services record keeping system: Reproductive status of married women age 15–49 Use of family planning method Breastfeeding of children Vaccination of mothers and children Children’s morbidity and health-care seeking GIS information system: Geo-coordinates of bari and households, tube-wells, health facilities, educational institutes, mosques, temples, rivers and roads Household roster: Identification (village, bari, household and person) Name, age and sex of the member Education, occupation and marital status Membership of non-government organizations Household socioeconomic status: Water and sanitation condition Household possession of durable assets Sources of income and food security Registration of birth: Identification of baby, father and mother Pregnancy history of the mother Sex, date and place of birth Duration of pregnancy, multiple births pregnancy and antenatal care visits by trimester Registration of death: Identification of deceased Age, sex, date and place of death Verbal autopsy (open narratives, signs and symptoms that led to death; medical treatment and lifestyle) Registration of migration (in and out): Identification of migrant Age, sex and date of migration Education, occupation and marital status of migrant Place of origin or destination of migrant Reasons for migration Pregnancy history of ever married women of reproductive age Registration of marriage and divorce: Identification of partner(s) Age, sex, education and occupation of the partners Date of event and registration with legal department Previous marital status of the partners Transaction of marriage gift and dowry Reasons for divorce Registration of internal movement: Date of movement within the HDSS area Creation of new household and household split Cause of movement Registration of change in household head: Date of change Reason for change in headship Age and sex of new head Altered relationship with household members due to change MCH-FP services record keeping system: Reproductive status of married women age 15–49 Use of family planning method Breastfeeding of children Vaccination of mothers and children Children’s morbidity and health-care seeking GIS information system: Geo-coordinates of bari and households, tube-wells, health facilities, educational institutes, mosques, temples, rivers and roads Variables collected during routine household visits in the Matlab HDSS area Household roster: Identification (village, bari, household and person) Name, age and sex of the member Education, occupation and marital status Membership of non-government organizations Household socioeconomic status: Water and sanitation condition Household possession of durable assets Sources of income and food security Registration of birth: Identification of baby, father and mother Pregnancy history of the mother Sex, date and place of birth Duration of pregnancy, multiple births pregnancy and antenatal care visits by trimester Registration of death: Identification of deceased Age, sex, date and place of death Verbal autopsy (open narratives, signs and symptoms that led to death; medical treatment and lifestyle) Registration of migration (in and out): Identification of migrant Age, sex and date of migration Education, occupation and marital status of migrant Place of origin or destination of migrant Reasons for migration Pregnancy history of ever married women of reproductive age Registration of marriage and divorce: Identification of partner(s) Age, sex, education and occupation of the partners Date of event and registration with legal department Previous marital status of the partners Transaction of marriage gift and dowry Reasons for divorce Registration of internal movement: Date of movement within the HDSS area Creation of new household and household split Cause of movement Registration of change in household head: Date of change Reason for change in headship Age and sex of new head Altered relationship with household members due to change MCH-FP services record keeping system: Reproductive status of married women age 15–49 Use of family planning method Breastfeeding of children Vaccination of mothers and children Children’s morbidity and health-care seeking GIS information system: Geo-coordinates of bari and households, tube-wells, health facilities, educational institutes, mosques, temples, rivers and roads Household roster: Identification (village, bari, household and person) Name, age and sex of the member Education, occupation and marital status Membership of non-government organizations Household socioeconomic status: Water and sanitation condition Household possession of durable assets Sources of income and food security Registration of birth: Identification of baby, father and mother Pregnancy history of the mother Sex, date and place of birth Duration of pregnancy, multiple births pregnancy and antenatal care visits by trimester Registration of death: Identification of deceased Age, sex, date and place of death Verbal autopsy (open narratives, signs and symptoms that led to death; medical treatment and lifestyle) Registration of migration (in and out): Identification of migrant Age, sex and date of migration Education, occupation and marital status of migrant Place of origin or destination of migrant Reasons for migration Pregnancy history of ever married women of reproductive age Registration of marriage and divorce: Identification of partner(s) Age, sex, education and occupation of the partners Date of event and registration with legal department Previous marital status of the partners Transaction of marriage gift and dowry Reasons for divorce Registration of internal movement: Date of movement within the HDSS area Creation of new household and household split Cause of movement Registration of change in household head: Date of change Reason for change in headship Age and sex of new head Altered relationship with household members due to change MCH-FP services record keeping system: Reproductive status of married women age 15–49 Use of family planning method Breastfeeding of children Vaccination of mothers and children Children’s morbidity and health-care seeking GIS information system: Geo-coordinates of bari and households, tube-wells, health facilities, educational institutes, mosques, temples, rivers and roads Administratively Matlab is one of 488 sub-districts in Bangladesh and is under Chandpur district. It is located between latitudes 23o 29’ 36.45’’ and 23o 17’ 30.20’’ north and longitudes 90o 48’ 07.01’’and 90o 36’ 58.72’’ east at 55 km south-east of the capital city Dhaka (Figure 1). The area under surveillance is 184.4 km2 with 1248 people per km2 as of 30 June 2014. Map showing locations of MCH-FP programme, health facilities, rivers, embankment and roads in the Matlab HDSS area. Matlab is ecologically in a regularly flooded area of Bangladesh, intersected by a network of tidal rivers, streams, channels and branches of the large rivers, the Padma and the Meghna. There was a severe flood in 1974 which resulted in a famine in the country in 1974–75.5 The construction of a 60-km embankment in 1986 created an effective flood control barrier and year-round irrigation facilities on the west side of the river that bisects the HDSS area. Climate is subtropical and the tropic of Cancer passes through the area. There are traditionally six seasons (namely summer, rain, autumn, late autumn, winter and spring) in a Bengali year. Climatologically there are three prominent periods: monsoon (July–October) with average rainfall of 152 cm and temperature ranging 23°–38°C; dry winter season (November–February) with no or little rain and temperature ranging from 13°–29°C; and hot dry season (March–June) with some rain and temperature ranging from 26°–38°C. Both temperature (rise in number of days with temperature ≥ 32°C days and fall in number of cold days below 12°C per year) and rainfall (rise in heavy rainfall in pre-monsoon and frequency of extreme events such as cyclones of more than 200 km/h) indicate climate change.6 With population growth, overall economic development and inflow of foreign remittances, there is rapid urbanization surrounding sub-district towns due to migration from relatively remote rural areas and resultant expansion of the urban area. The majority of the population under surveillance are Muslims (88.2%) and the rest are Hindus, as of 2014, and all are ethnically Bengalee.7 The main occupations of men are agriculture, fishery and trade. Women are mainly occupied with household chores. Labour migration and economic migration are male biased, which increases female-headed households–to 35% in 2014 from 11% in 1974.7 The government of Bangladesh provides primary health care services through a three-tiered health service delivery system: community clinics, each serving about 6000–10 000 people;8 Union health and family welfare centres, each serving 25 000 people; and Upazila (sub-district) health complexes, each serving 250 000 people, charging a nominal fee and coordinating services between different tiers (Figure 1). The icddr,b Matlab field diarrhoea hospital was set up in December 1963 primarily to support cholera vaccine trials and provide free treatment to all members of the community suffering from diarrhoeal disease, whether they live within or outside the surveillance area.9 In 1977 the MCH-FP programme set up four community-based treatment sub-centres in the programme area to manage maternal, newborn and child health problems locally and give referrals when needed to the MHC-FP clinic established in Matlab hospital. The MCH-FP programme initiated promotion of sub-centre delivery in 1997, established fixed site clinics for delivering MCH-FP services in 2000, and initiated maternal, newborn and child health interventions in 2007 to be more comprehensive.10 Both areas are similar in public primary health care infrastructures, but there are more private fee-for-service clinics and untrained health care providers (i.e. village doctors, pharmacies, homeopaths and herbalists) in the programme area. Over the past five decades, Matlab HDSS has recorded thousands of births, deaths, migrations, marriages and divorces as well as maternal and child health information, using simple paper forms entered by hand into a computerized database at Matlab. New technology was introduced in HDSS, allowing the existing paper forms to be scanned in 2007, followed by the introduction of PDAs (personal digital assistants) in 2010 for direct data capture, Galaxy Tab-3 in 2014 and verbal autopsy in 2015, completely bypassing the use of paper forms. Field data are edited in Matlab and exported to the destination database in Dhaka for longitudinal matching. Following a household socio-demographic census of de jure population in 1966, trained female community health workers (CHWs) with some education used to visit households bi-weekly to record demographic events. Health assistants (HAs with education ≥ 10th grade), accompanied by the CHWs of respective areas, used to visit households monthly to confirm events and filled-in event registration forms. Matlab HDSS started registration of marriages and divorces in 1975 and internal movement within the surveillance area in 1982. Finally, recording of household splits and change in household headship the (household head is an active senior member of the household who cares for all members and makes decision in major households issues irrespective of his or her earning status) started in 1993. The CHWs were re-designated as community health research workers (CHRWs) in 1999, and HAs as health research assistants (HRAs) in 2000. The event registration forms in English were designed in Bangla, and female CHRWs with at least 8th grade education were given the responsibilities of HDSS data collection, including filling in of all event registration forms, and field supervision in 2001. They have been trained to record verbal autopsy of deaths (and a few numerically) in their catchment areas since 2003, during their routine field supervisory visits for HDSS. Routine household visits by CHRWs for data collection were increased from monthly to bi-monthly in 2007. Household socioeconomic data, including education and occupation of individuals, have been collected periodically in 1966, 1974, 1982, 1996, 2005 and 2014. The spatial database contains geo-locations of baris, tube-wells, ditches, ponds, villages, health facilities, educational institutes, mosques, temples, markets, rivers and roads. It is periodically updated with geo-coordinates of new baris, tube-wells, health facilities, educational institutes etc. Estimation during 2002–03 of arsenic in tube-wells water used for drinking added a new dimension to research into its effect on morbidity and mortality by cause (Figure 2). Map showing level of arsenic in tube-well water in the Matlab HDSS area in 2002–03. (Bangladesh Government safe limit is 50 µg/l and WHO safe limit is 10 µg/l). Residents of the HDSS area, in case of diarrhoeal illness, can visit the field hospital carrying HDSS family visit records that contain assigned unique IDs for treatment, as required for hospital surveillance and evaluation of any other intervention. In case of failure to carry HDSS ID, conventional identifiers (name, bari and village) are used to get the HDSS ID. In the MCH-FP programme area, mothers and children aged < 5 years get MCH-FP services from four treatment sub-centres. The Matlab field site is equipped with laboratory and other infrastructures required for research. A weather station on the roof of the Matlab hospital was set up in August 2008 for closely monitoring weather change. On the eve of rising prices of essentials and grains globally and in local markets in 2008, a sample surveillance covering 2000 households was set up for periodical assessment of household food security and dietary diversity during 2008–13. CHRWs with a standard consent form inform the household heads/caretakers about the purpose of recording health and demographic events and guarantee confidentiality of information they provide. Willingness to take part is expressed by signature or thumb impression. Informed consent thus taken remains valid until it is withdrawn. Refusal is rare and the community has always been supportive of icddr,b activities in Matlab, as they get free treatment for diarrhoea and also employment opportunities. Vital events, migrations and maternal and child health information in each calendar year are processed to compute and compare health and demographic indices for preparing HDSS annual reports, with soft copies in web pages. From the HDSS routine annual reports, demographic trends in terms of change in fertility, age at marriage, population structure, mortality, cause of death, life at population movement etc. can be and used as a for health service planning and of arsenic in water were for tube-wells in 2002–03 (Figure and new tube-wells in 2014. level in tube-well water is to the of the tube-well water in the HDSS area. The Matlab HDSS database is designed to be longitudinal and and to data events deaths, marriages and migrations of all and their with household The event and migration forms are entered into a computerized database as event With the of event data are edited for of for that are of or through of the event forms and field visits in some The edited event data are exported to the destination database in Dhaka for of the events with household of the database with information, in a to population at compute rates at any and and economic interventions. The database of the and of the with the household head at any and to research on of diseases and other health The database is on the 10 with and is in the field are entered with existing data, and using Routine are to and data support High population in country was as a major development in the and HDSS data the of the MCH-FP programme in controlling fertility and maternal, and child in a led to the in with an of of the Matlab programme into the in female marriage rural but as as it in HDSS data that the vaccine given to women in 1974 was effective in mortality in children to in the A from increased mortality and oral vaccine of provoked of HDSS data on and mortality, which reduced mortality children who HDSS data the effects of the famine and of demographic events such as maternal death or on and child in rural and development of the HDSS data as a of deaths in a in the Matlab HDSS area with HDSS records of maternal deaths during an of maternal mortality by the Household is an established method for rates of rare events death, but a large sample The in the HDSS area that of rare events in their the or change in maternal mortality and mortality or with a fertility research that economic from and the of to fertility Both fertility and control of diseases resulted in a major in diseases more households below the and is on in from rural to urban areas or has household economic with households with no migration or migration to other rural Matlab HDSS for five has been and remains a for studying at different of the and socioeconomic household socioeconomic provide rare to and of and and children to poor households of as they in rural There are seeking to the of for age at marriage in female of fertility and on health and of household members and and care of the in of in female education and of employment in rural areas change the sex in the of HDSS and socioeconomic data are and the construction of the embankment in of the of the MCH-FP programme in late 1977 and of arsenic in tube-well water in for and are to of the effects the the MCH-FP development and arsenic on of health and Matlab HDSS, a longitudinal the of rates and of relatively rare health and demographic events. socioeconomic monitoring of in socioeconomic and in health and and to with GIS spatial data of of diseases and health events, of arsenic in tube-wells and in health service support to icddr,b research activities of new interventions. The HDSS site was in for its in a at a from an area of health and demographic of the programme area of the HDSS are to of the and is information on and child of for a routine system high of and high of HDSS data for five have been with and the in since of who are with other and also use the HDSS data to use HDSS data icddr,b data and get in HDSS longitudinal data have effects of delivery of MCH-FP services on fertility and mortality of deaths due to and and on mortality, and have design more effective health and family planning HDSS data have effects of vaccine on mortality and vaccine on child of maternal deaths by the and the of of maternal deaths for monitoring HDSS has as a training site for programme planners and implementers of from developing countries. Verbal in the HDSS of design of health interventions to estimate mortality effects by and development of for of of research is by who provide support to icddr,b for its and research. support Government of the of International and the for International for their support and to research Matlab HDSS is a member site of the of

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