Dissimilar approaches to certifying causes of death and/or selecting underlying cause may diminish the usefulness of cause-specific mortality data. The similarity of certifying and coding practices within a country is especially crucial for providing reliable information on the epidemiological situation in the population.
In the current study, we use an indirect technique to analyze the consistency of cause-specific mortality statistics at the subnational level in four countries, which have rather different systems on producing information on causes of death - France, Germany, the USA, and Russia. Based on the cause-specific mortality data, we estimate the prevalence of major groups of causes of death at the subnational level (regions) and compare it with the inter-regional average prevalence. We visualize deviations from the inter-regional average through the heatmap to identify suspicious outliers that are unlikely to be solely explained by real differences in morbidity and mortality prevalence.
Using the proposed approach, we found that the French system of producing information on causes of death results in a high level of comparability across subnational entities. In Germany, the USA, and Russia, we found cases of significant deviation from an inter-regional average level. That potentially indicates specific peculiarities in certifying causes of death and/or selecting the underlying cause of death.
The causes of death, which are easy to be recognized as underlying, showed high consistency across subnational entities in all the four countries. On the contrary, causes that do not have very strict diagnostic criteria and/or often accompanied by comorbidities tended to have higher variability.