Surveillance - Prospective death reporting
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Almost every country in the world has a prospective death reporting system. In most countries, death registration is mandatory. Health workers who attended the person just before death or who are familiar with the circumstances of the death are required to report certain data, such as name, age at death, and cause of death, to public health authorities, who then add up the number of deaths periodically to calculate mortality rates. Death reporting is often part of a vital statistics system which records information on births, deaths, marriages, and divorces.
In most developed countries, this system is relatively complete, and the mortality rates calculated from the data are reasonably accurate. However, in many less-developed countries, vital statistics systems are very incomplete. Many deaths may occur outside of the health system; such deaths may go unreported. Even in countries with well-functioning systems, such systems often break down early in an armed conflict. This may be because a large proportion of deaths occur outside health facilities, the registration workers have fled, or logistical barriers to reporting and record keeping increase during conflict.
In most humanitarian emergencies, it is essential to implement prospective death reporting as soon as possible so that the mortality rate can be closely followed. Data for such reporting systems may come from:
- Clinic and hospital staff reporting to public health authorities deaths which occur in these facilities
- Religious authorities reporting deaths for which they conduct ceremonies
- Civil authorities reporting which are recorded in local population registries or other lists
- Counting new graves at a community's burial site
- Counting the number of times death benefits are distributed. Public health authorities can provide a shroud or coffin for burial or funeral expenses.
At the very least, death reporting should include reporting from all health facilities in the population, including hospitals, clinics, feeding centres, maternity homes, etc. Health workers in these facilities should complete a specific form giving some basic information on the person who has died, such as age, sex, and an estimate of the cause of death. The specific reporting sources may differ depending on the circumstances of each population.
Prospective death reporting can provide data allowing calculation of much more up-to-date mortality rates. An example is shown here.
This graph makes it clear that, while mortality rates declined within a few months in three of the populations, the rate rose in Eastern Ethiopia in 1988-1989. Persons monitoring mortality rates should have investigated this rise in mortality rates more closely.
Prospective mortality reporting is never 100% complete. Nonetheless, if the completeness of mortality reporting is stable, that is, the same proportion of deaths are reported over time, it should be possible to assess mortality trends even with relatively incomplete data.
Of course, even if complete, prospective mortality surveillance provides only the numerator of the mortality rate. The denominator, the population size, must come from another source. In acute humanitarian emergencies, estimates of population size are notoriously unreliable. And if the population estimate changes, it will result in changes in the calculated mortality rate.
Uncertain population denominator
Population size was so uncertain in Goma, Zaire in July and August 1994 that crude mortality rates were calculated using several estimated population sizes. It turned out that after registration of the camp populations, the smallest estimate was most accurate. If crude mortality rates had been calculated only using the overestimated population size initially, switching to the lower, more accurate, population size would have resulted in a sharp increase in apparent crude mortality rate.
If you see a sharp change in mortality rate from one time period to the next, check to see if the population denominator used to calculate the rate changed. If it did, the apparent change in mortality rate may not reflect a real change in the actual rate mortality in the population.