Towards real-time mortality surveillance by medical causes of death: A strategy of analysis for alert

Abstract

Background In 2004 the French Public Health Agency set up a reactive all-causes mortality surveillance-based on the administrative part of the death certificate, in the final objectives: –to detect unexpected or usual variations in mortality; –to provide a first evaluation of mortality impact of public health events. In 2007, an Electronic Death Registration System (EDRS) was implemented, enabling electronic transmission of the medical causes of death to the agency in real time. It allows approaching the cause accountability when an excess death is observed. A strategy has been developed for the analysis in routine of the medical causes of death with the objectives of early detection of expected and unexpected events and reactive evaluation of the impact of these events. The aim of this study is to present the syndromic indicators and their definitions that will be routinely followed for mortality surveillance. Method Mortality syndromic indicators were defined as a cluster of medical causes of death (pathologies, syndromes or symptoms) with the same nosological meaning and meeting the objectives of alert and impact evaluation of mortality surveillance. The causes of death are either free-text (words, terms, expressions) or ICD-10 codes. To build the pertinent syndromic indicators, we explored multiple biomedical classifications such as the Mesh, SNOMED, UMLS. We also used a dictionary [provided by the Center of Epidemiological Causes of Death (Inserm-CepiDc)] of each term/expression found in the death certificates since 2005 and the associated ICD-10 code. Each indicator and its definition were also discussed in working groups including medical and epidemiological experts. Result The list of established indicators was composed of: –indicators for detection of expected seasonal events such as: “influenza”, “pneumonia”, “gastroenteritis”, “chikungunya”, “heat related death”, “dehydration”…; –other complementary indicators for detection of the impact of unexpected events such as: “epilepsy”, “aneurysm rupture”, “pulmonary embolism”, “choc”, “coma”, “unspecified fever”, “headache”…; –indicators for the decomposition of the mortality linked to an event; they include the previous indicators. Examples of detection of winter seasonal events and heat related events will be presented as well as the detection of death with chikungunya cause in the death certificate. Conclusion The use of free-text causes of death for mortality surveillance required the development of a strategy for the analysis of these data. The building of a list of syndromic indicators for alert and impact evaluation was essential for the implementation of systematical classification methods of the death certificates in routine.