Health and demographic surveillance sites in Ethiopia: a scoping review of infrastructure and gaps for longitudinal studies on health and aging

Health and demographic surveillance sites (HDSS) provide sampling frames to conduct longitudinal studies. This review aims to provide a comprehensive characterization of HDSS in Ethiopia and assess its potential as a robust infrastructure for longitudinal studies on aging-related and other health outcomes. We searched databases including PubMed for peer-reviewed articles, HDSS reports, strategic papers, and other pertinent literature, and extracted pertinent information. Projection of adult population (aged ≥40 years) for the respective HDSS was done based on the estimated growth rate. From a total of 979 articles, 56 were included in the review. Currently, 11 HDSS are present in Ethiopia, and each has more than 9,000 households with an average household size of at least three. HDSS have unique characteristics and are designed to focus on respective geographic and demographic contexts. A total of 27 districts (1-6 districts per HDSS) and 12 sub-districts are included across all HDSS. The number of adults aged ≥40 years is projected to rise from 210, 673 in 2024 to 295,780 in 2037, indicating their potential as infrastructure to conduct studies on aging. Limited geographic coverage across regions and resource constraints are identified gaps in HDSS. Major cities, urban areas, and remote areas may lack sufficient coverage or representation. In light of the anticipated significant increase in the number of older adults in the HDSS capture sites, HDSS can serve as an infrastructure for conducting studies on aging-related and other health outcomes in Ethiopia.