Validation of an in-house Dutch Forensic Death Coding system (FDC).

Background: The International Classification of Diseases (ICD-11), developed by the WHO, is widely used to code and classify causes of death. While it is a suitable system for clinical data, it is not tailored for forensic diagnoses. This article explores the basic principles and methods for classification of cause of death in a forensic setting. An in-house Dutch coding system, the FDC system, was developed in the Netherlands.

Objective: To determine the validity and applicability of the FDC system.

Methods: The FDC system was used to code 138 deaths based on the forensic autopsy reports of the Netherlands Forensic Institute. This was performed by three investigators (one forensic pathologist and two forensic physicians, all of whom are forensic experts) to compute the inter-investigator agreement using Krippendorff's alpha (kalpha) statistics. To measure the intra-investigator agreement, 46 cases per investigator (for each investigator different cases) were presented twice in random order. The coding system has five parameters: Main category, Subcategory, Other contributing factor category, Mode of death category, and Certainty of death category.

Results: The Krippendorff's alphas (kalphas) for the inter-investigator agreement were as follows: Main category 0.91, Subcategory 0.74, Mode category 0.49 and Certainty category 0.55. Inter-investigator agreement showed high kalpha scores for both Main category and Subcategory. There was a good intra-investigator agreement. The kalphas were as follows: Main category 0.95, Subcategory 0.87, Mode category 0.65, and Certainty category 0.78.

Conclusions: The FDC system is an in-house Dutch system that is useful for coding causes of death from a forensic perspective. This system could make the notation of forensic pathologists and forensic physicians less ambiguous, which could improve the understanding of cases by professionals such as public prosecutors, lawyers and judges who have to make decisions based on autopsy reports. In the future, this system could also be used in forensic medicine by forensic physicians and for (forensic) mortality reporting in public health statistics.