Chapter 2 Sample Registration System Defined: Sample-Based Mortality Surveillance System (SMSS)

Setel and colleagues defined a SRS as “a community-based system implemented in a nationally representative cluster sample”¹⁰. SRS is a sustained continuous rigorous data collection and analysis approach that relies on a sample of the population organized in geographic clusters and drawn to be nationally and sub-nationally representative with the aim of producing population empirical estimates of mortality and cause of death and other population demographics. The name SRS can be misleading as the system does not aim to legally register events births and identify deaths. Its main purpose is to generate data for statistics, as opposed to a CRVS which is mandated for legal registration and official documentation of vital events. By design, an SRS does not exhaustively cover the entire population of a country but collects data from only a small fraction (1-5% depending on total population size) to make inferences on the entire population. Depending on resources and country needs, the population covered can be selected in such a way that population indicators measured are representative at specified statistical domains, which can be national, regional/provincial, or district-level. Thus, an SRS is a sample vital statistics system, often limited to most relevant vital events such as births, deaths, and population counts. Given the centrality of collecting mortality data, we will refer to it as a Sample-based Mortality Surveillance System (SMSS). Throughout the manual, we refer to SRS as SMSS.

Defining mortality surveillance
A SMSS involves: Continuous near real-time data collection on births, deaths, and causes of death, consistently with existing global or national standards. Ideally, updated population counts by age and sex. Geographically contained and sample-based estimates, whether national or subnational, with population representativeness Data analysis to produce reliable and interpretable estimates of all-causes and cause-specific mortality with relevant disaggregation (by age, sex, and other selected characteristics). Regular data release for use in policy and program decision-making, learning, and research.

A SMSS involves:

Continuous near real-time data collection on births, deaths, and causes of death, consistently with existing global or national standards.
Ideally, updated population counts by age and sex.
Geographically contained and sample-based estimates, whether national or subnational, with population representativeness
Data analysis to produce reliable and interpretable estimates of all-causes and cause-specific mortality with relevant disaggregation (by age, sex, and other selected characteristics).
Regular data release for use in policy and program decision-making, learning, and research.

Overview of How to Create an SMSS

Designing and successfully implementing an SMSS is a longterm commitment that must be guided by a government vision of establishing a sustainable surveillance system for rapid mortality and cause of death data generation and use. Such systems must be guided by six main principles that ensure that consideration and value is given to the existing data system through possible linkages or integration, key stakeholders and players at the country level are engaged, and progress and priority toward full functioning of civil registration and vital statistics is not diminished. The box below summarizes these six guiding principles. Countries or users may define additional principles depending on their specific context and objectives of the surveillance system being pursued.

Six Guiding Principles for Establishing a Mortality Surveillance System
The collection of mortality statistics is complex and requires the involvment of multiple sectors and stakeholders that are interested in these statistics. Many countries are already implementing various surveillance systems that are at different levels of maturity. The proposed surveillance system must leverage and build on existing country digital tools and surveillance systems rather than creating a completely new and parallel system. New platforms may be proposed to support additional data collection, in order to enhance or fill gaps in existing platforms, but they must incorporate linkages and interoperability with key existing government systems. The proposed mortality surveillance system must value, support, and strengthen the country’s vision for establishing a long-term CVRS. The proposed system has a data production function solely and does not seek to interfere with the legal framework of CRVS or the service delivery function of other existing systems, although it may support the optimal functionality of these systems regarding these objectives.

The collection of mortality statistics is complex and requires the involvment of multiple sectors and stakeholders that are interested in these statistics.
Many countries are already implementing various surveillance systems that are at different levels of maturity.
The proposed surveillance system must leverage and build on existing country digital tools and surveillance systems rather than creating a completely new and parallel system.
New platforms may be proposed to support additional data collection, in order to enhance or fill gaps in existing platforms, but they must incorporate linkages and interoperability with key existing government systems.
The proposed mortality surveillance system must value, support, and strengthen the country’s vision for establishing a long-term CVRS.
The proposed system has a data production function solely and does not seek to interfere with the legal framework of CRVS or the service delivery function of other existing systems, although it may support the optimal functionality of these systems regarding these objectives.

More concretely, the development of an SMSS requires twelve key steps which are presented on the following page. These four phases are continuous throughout the life of the SMSS. These are enumerated below and constitute the common thread and outline of this manual. Each step is further detailed in each section of the manual.

Taking a big picture view, the steps that can be organized in six distinct phases that we refer to as the lifecycle of an SMSS. These six phases are divided into two components. The start-up component includes the phases of conception, planning, and launch which are completed when the system is first established. The recurrent components include: routine data collection and transfer; data review, analysis, integration and use; and assessment, adjustment, and sustainability.

As shown in the diagram below, the timing of the individual steps can overlap. Although the duration of each step will vary according to the context, the approximate duration is presented below.

Timing and Duration of SMSS Implementation Steps

To learn more:

A Door-to-Door Effort to Find Out Who Died Helps Low-Income Countries Aid the Living · A 2022 New York Times article about a sample registration system in Sierra Leone.
The Lifesaving Power of … Paperwork? ·A New York Times article from 2023 explaining a surveillance system in rural Colombia.
National Sample Vital Registration System: A sustainable platform for COVID-19 and other infectious disease surveillance in low and middle-income countries. · A 2020 journal commentary.
Addressing the Gaps in Mortality Data: A Case for National Mortality Surveillance · A commentary by the guest editor of the supplement in The American Journal of Tropical Medicine and Hygiene which described the COMSA Mozambique project.

Setel PW, Sankoh O, Rao C, Velkoff VA, Mathers C, Gonghuan Y et al. Sample registration of vital events with verbal autopsy: a renewed commitment to measuring and monitoring vital statistics. Bulletin of the World Health Organization 2005;83:611-617↩︎