Background: The validity of mortality statistics is specific to causes of death and depends on the quality of death certificates. The proportion of noninformative underlying causes of death in all deaths is an indicator for the validity of a mortality statistic. The most frequent noninformative cause of death involves cardiovascular diseases (ICD-10: I00-I99).
Objectives: Regional differences in the frequency and type of use of noninformative cardiovascular causes of death are investigated and their effect on the mortality rate of ischemic heart disease is presented.
Materials and methods: Mortality rates for cardiovascular causes of death by gender, age group, and federal state were extracted from the Information System of the Federal Health Monitoring (GBE) for 2000, 2010, 2015, and 2016. The proportion of noninformative causes of death in all cardiovascular deaths, as well as the mortality rate for ischemic heart disease after recoding noninformative causes of death, were calculated.
Results: The proportion of noninformative causes of death in all cardiovascular deaths is high and depends on age, sex, federal state, and year of death. Regional differences in frequency and type of use were found. After recoding selected noninformative causes of death, the mean increase in the mortality rate for ischemic heart disease in all federal states was 33%.
Discussion: A comparison of cause-specific mortality rates between regions, sexes, and over time is affected by differences in the use of noninformative causes of death. Improving the quality of death certificates is a prerequisite for valid mortality statistics.
Keywords: Garbage codes; Ischemic heart disease; Mortality statistic; Quality of death certificates; Regional differences.