Rue Juliette Wytsmanstraat 14 | 1050 Brussels | BelgiumT +32 2 642 5035 | [email protected] | http://www.wiv-isp.be
The disease burden of infectious diseases in Belgium
Brecht Devleesschauwer18/05/2017
The disease burden of infectious diseases in Belgium
The disease burden of infectious diseases in Belgium
Burden of disease
• How to define disease “impact” or “importance”?
• Disease have an impact on multiple aspects
Burden of disease = quantification of any of these aspects
This requires specific metrics
The disease burden of infectious diseases in Belgium
Burden of disease
• Which disease is most important?
Number of cases, number of deaths Severity of case: duration, reduction quality of life Severity of death: residual life expectancy
Summary Measures of Population Health
The disease burden of infectious diseases in Belgium
Disability-Adjusted Life Years
• 1 DALY = 1 healthy life year lost• Summary measure of population health Morbidity + mortality Disease occurrence + disease severity
• DALY = YLD + YLL YLD = Years Lived with Disability
= Number of incident cases×Duration×Disability Weight YLL = Standard Expected Years of Life Lost
= Number of deaths×Residual Life Expectancy
The disease burden of infectious diseases in Belgium
Disability-Adjusted Life Years
DALY = YLD + YLL YLD = Years Lived with Disability = N×D×DW YLL = Years of Life Lost = M×RLE
The disease burden of infectious diseases in Belgium
20 60Age
DW
01
0
90
40 × 0.25= 10 YLDs
30 × 1= 30 YLLs
0.25
10 + 30 = 40 DALYs
Disability Weights
• Relative severity of symptom/health state 0 = 0% = perfect health
1 = 100% = worst possible health state, death
The disease burden of infectious diseases in Belgium
0 10.005: hearing loss, minor 0.433: migraine
0.494: amputation of both legs, without treatment
0.756: schizophrenia, acute stage
0.072: controlled epilepsy
Disease models
Disease model, outcome tree• Schematic representation of “health states” acute, chronic stages complications (sequelae, long-term health outcomes) death + multiple severity levels
The disease burden of infectious diseases in Belgium
Disease models
The disease burden of infectious diseases in Belgium
Campylobacter spp.
DALY calculation in practice
The disease burden of infectious diseases in Belgium
Study population definition
Disease model definition
Data collection Data adjustment
DALY calculation
Surveillance pyramid
• Tip of the ice berg• .. through the eyes of a
drunken sailor
The disease burden of infectious diseases in Belgium
Underestimation
MultiplicationFactors
Data adjustments
The disease burden of infectious diseases in Belgium
Apparent incidence
True incidence
DALYsMultiplication
factors
Disease model
Burden of Infectious Diseases
• ECDC: Burden of CommunicableDiseases in Europe (BCoDE) 32 communicable diseases 6 healthcare associated infections Burden of disease “toolkit”
• WHO: Foodborne Disease BurdenEpidemiology Reference Group (FERG) 31 foodborne microbiological and
chemical hazards http://collections.plos.org/ferg2015
The disease burden of infectious diseases in Belgium
Burden of Infectious Diseases
The disease burden of infectious diseases in Belgium
Burden of Infectious Diseases
The disease burden of infectious diseases in Belgium
Burden of Infectious Diseases
WIV-ISP National Burden of Disease Study• Burden of community-acquired infectious diseases surveillance data + correction factors BCoDE & FERG disease models
• Burden of healthcare-associated infectious diseases point prevalence survey (2011, 2017) BCoDE disease models
• Results expected end 2017
The disease burden of infectious diseases in Belgium
Burden of Infectious Diseases
PhD research• Burden of congenital toxoplasmosis and
cytomegalovirus infection Suzanne Smit, UGent/UCL
• Burden of bacterial foodborne diseases Charline Maertens de Noordhout, UCL
• Burden of Lyme disease Laurence Geebelen, WIV-ISP/UCL
The disease burden of infectious diseases in Belgium
Burden of Infectious Diseases
Burden of congenital toxoplasmosis and CMV• Public health impact of congenital toxoplasmosis and
cytomegalovirus infection in Belgium, 2013: a systematic review and data synthesis (Clinical Infectious Diseases, in press)
The disease burden of infectious diseases in Belgium
Disease Incidence DALYs DALYs per case
Congenitaltoxoplasmosis
69(18–131)
188(43–419)
2.7(1.2–5.0)
CongenitalCMV infection
651(516–802)
1976(757–4067)
3.0(1.8–5.2)
Discussion
Acknowledge limitations
• Measures problems, not solutions potential for health gain, unmet needs does not replace cost-effectiveness studies
• Health impact is just one of many aspects
The disease burden of infectious diseases in Belgium
• economic impact• rare, but severe• stakeholder interests• general awareness• …
Discussion
Relevance of burden of infectious diseases estimates?• Public health policy monitor trends, evaluate past actions, inform new
prevention/control
• Research identify “unmet medical needs”
• Clinical laboratories information on underreporting
• General practitioners contribute to differential diagnosis, patient awareness
The disease burden of infectious diseases in Belgium
Rue Juliette Wytsmanstraat 14 | 1050 Brussels | BelgiumT +32 2 642 5035 | [email protected] | http://www.wiv-isp.be
Thank you
Burden of Infectious Diseases
Burden of bacterial foodborne diseases• Burden of salmonellosis, campylobacteriosis and
listeriosis in Belgium from 2012 to 2020: a time series analysis (Eurosurveillance, in press)
The disease burden of infectious diseases in Belgium
SalmonellosisCampylobacteriosisListeriosis