Completeness and coverage of death registration data
Considerable differences exist in the degree of completeness of the vital registration data submitted by countries. In some countries, the vital registration data system covers only a part of the country (for example urban areas, or some provinces only). In some other countries, although the vital registration data system covers the whole country, not all deaths are registered.
Each Member State reports population data along with their mortality data, for the population covered by the death registration system. Where this is a subset of the national population, the data is labelled accordingly in the WHO Mortality Database, e.g. Brazil (North and North-east) or Paraguay (reporting areas). However, the completeness of death registration may also be less than 100% for the specified registration population. For Member States with incomplete vital registration systems, demographic techniques have been used by WHO to estimate the level of completeness of death recording for the specified population to allow the calculation of mortality rates. These population data are provided along with the deaths data. The proportion of all deaths which are registered in the population covered by the vital registration system for a country (referred to as completeness) has been estimated by WHO for the latest available year and is given in a table available on this website
Note that vital registration data may be 100% complete for the population covered, but not include full coverage of deaths in the country. The overall level of coverage for the latest available year for each country is also listed in a separate table. Coverage is calculated by dividing the total deaths reported for a country-year from the vital registration system by the total estimated deaths for that year for the national population. The national population estimates used are those of the UN Population Division 2002 revision. Best estimates of mortality rates by age and sex, adjusted for incompleteness and incomplete coverage, are applied to the national population data to obtain total estimated deaths. WHO estimated coverage for a Member State may be less than 100% due to incompleteness of registration, or to coverage of only some parts of the national population, or to differences between the vital registration population and the UN estimated de-facto population.
Death registration coverage and cross-national differences in coding practices, particularly in the use of codes for ill-defined and unknown causes, must be taken into account to validly compare mortality rates for specific causes across countries. Additionally, where coverage is less than 100%, the cause of death distribution for the uncovered population may differ from that of the covered population.