Cohort profile of the largest health & demographic surveillance system (Dibrugarh-HDSS) from North-East India

Dibrugarh Health and Demographic Surveillance System (Dibrugarh-HDSS), was started in the year 2019 with the objective to create the health and demographic database of a population from a defined geographical area and a surveillance system for providing technical assistance for the implementation of programmes and formulating intervention strategies for reducing disease morbidities and mortalities in the population. Dibrugarh-HDSS adopted a panel design and covered 60 contiguous villages and 20 tea gardens. Line listing of all the households was conducted and a unique identification number detailing State, district, village/tea garden and serial number was provided along with geotagging. Detailed sociodemographic variables, anthropometric measurements (subjects ≥five years) and blood pressure data (subjects ≥18 yr), disease morbidity and mortality were collected. All data were collected in pre-designed and pre-tested questionnaires using a mobile application package developed for this purpose. Dibrugarh-HDSS included a total of 106,769 individuals (rural: 46,762, tea garden: 60,007) with 52,934 males (49.6%) and 53,835 females (50.4%). The number of females per thousand males were significantly higher (1042 in tea garden vs. 985 in rural populations) in the tea-garden community as compared to the village population. More than one-third (35.1%) of tea populations were illiterate compared to the rural population (17.1%). Villagers had significantly higher body mass index than the tea-garden community. The overall prevalence of hypertension (adjusted for age) was 29.4 vs. 28.2 per cent, respectively, for the village and tea-garden population. For both these communities, males (village=30.8%, tea garden=31.1%) showed a higher prevalence of hypertension (adjusted for age) than females (village=28.2%, tea garden=25.8%). The findings of the present study give an insight into the profile of the native rural and tea-garden populations that will help to identify risk factors of different health problems, review the effectiveness of different ongoing programmes, implement intervention strategies for reducing morbidity and mortality and assist the State health authorities in prioritizing their resource allocation and implementation strategies.