In the project BURDEN 2020 - "The burden of disease in Germany and its regions" - the years of life lost (YLL) due to premature mortality are calculated on the basis of official cause-of-death statistics. This requires the identification and redistribution of the so-called ill-defined ICD codes. "Ill-defined" means that an ICD code does not sufficiently reflect the cause of death, such that it is not informative for the calculation of the burden of disease.The first steps on the way to calculating cause-specific YLL are presented. Different frameworks of ill-defined codes are compared. The number of deaths with ill-defined codes that can be found in the German cause-of-death statistics in absolute and relative terms are analyzed, including how they are distributed by age, sex, and region.According to the WHO framework, 15.6% of the 925,200 deaths in Germany in 2015 can be identified as ill-defined. According to the framework of the Institute for Health Metrics and Evaluation (IHME) in the Global Burden of Disease Study (GBD), the proportion of ill-defined codes is 26.6%. The ICD-related distribution patterns hardly differ between WHO and IHME classifications. Considerable differences exist between the federal states, with shares of ill-defined codes between 16 and 35% (IHME framework).The cause-of-death statistics in Germany contain a considerable proportion of ill-defined codes. The differences between the federal states can only partially be explained by different electronic data processing. Due to further dissemination and improvement of electronic data collection, higher quality of cause-of-death statistics can be expected in the future.
Keywords: Cause-of-death statistics; Ill-defined codes; Redistribution; Regional differences; Years of life lost (YLL).