gms | German Medical Science

Background: Current estimates of the burden of disease due to infectious conditions usually assess the impact of acute consequences and do not consider future long-term sequelae (e.g. HBV and hepatocellular carcinoma). To provide improved estimates of the burden due to infectious diseases in Europe, the ECDC launched a call for proposals in 2008 and initiated the BCoDE project in 2009. The main objectives of the study were to develop a methodology, and to measure and report the current and future burden of communicable diseases.

Methods: The BCoDE consortium used the approach developed by the Global Burden of Disease study (GBD) and a RIVM pilot study as starting points to develop a methodological framework for burden estimation tailored to meet challenges triggered by infectious diseases. Major modifications from the GBD approach were the use of a pathogen-based approach, the implementation of outcome-trees and integration of infectious disease dynamics. It was decided to use the Disability Adjusted Life Years (DALYs) measure to provide estimates of the burden due to communicable diseases.

Results: Using a pathogen-based approach allows for taking the burden of short- and long-term sequelae attributable to the initial infection into account. The outcome-trees are composed of a) health outcomes causally related to an infection with a specific pathogen, b) transition probabilities reflecting the probability of moving from one health state to another (e.g. percentage of acute HBV infections developing fulminant liver failure) and c) time spent in each health state. Information on the epidemiology of infectious pathogens under study was obtained from semi-systematic reviews, expert-opinion from disease-specific ECDC programs, and other European experts. Incidence data of an initial infection is required and used to model the disease burden of the remaining health outcomes in the outcome-tree. The input parameters are adjusted for under-ascertainment and under-reporting by use of multiplication factors obtained from semi-systematic reviews and expert-opinion.

Conclusions: Using a pathogen-based approach allows for more comprehensive burden of disease estimates because it includes long-term sequelae in the assessments. Using the BCoDE methodology, we can provide estimates of the current and model for future burden of infectious diseases. The current methodology has to be developed further in order to properly compare infectious diseases across long time scales and to take the dynamic nature of infectious diseases into account. Testing the feasibility of the methodology and the quality of modelled data is of major concern for the current pilot study in Estonia, Germany, Italy and the Netherlands.