Key elements ina surveillance system
Patrick Rolland
EPIET / EUPHEM Intro Course 2012
&
2
&
Le fil rouge in surveillance?
Surveillance isInformation for
action!
3
&
Good reminder: surveillance?
Langmuir AD., 1963
“Systematic collection, consolidation, analysis and dissemination of data on specific disease”
Thacker SB., 1996
“The final link is the application of these data to prevention and control”
4
&
Good reminder: surveillance loop
Data collection
Data analysis
Information
Action!
Evaluation
Objectives
5
&
Aim and content of the lecture
Aim: To understand key elements in a surveillance system
- From a clear understanding of the purpose
- To the right dissemination of information
Content- Main objectives of a surveillance system
- Checklist of key elements, step by step
6
&
Main objectives ofa surveillance system
7
&
Main objectives
Describe: produce information in terms of TPP
Alert: detect epidemics or emerging events
Evaluate: assess prevention or control measures
And also: Generate hypotheses for research
Detect changes in health practice
Plan public health actions and resources
8
&
But keep in mind the goal!
Surveillance isInformation for action!
By implementation of prevention and control measures
In order to reduce morbidityand mortality
9
&
Describe: Time = Graph
Source: GP network “Réseau unifié”
Week
Inci
denc
e (p
er 1
00,0
00)
Weekly incidence rate of flu-likesyndromes, 2009-2012, France
10
&
Describe: Place = Map
Weekly incidence rateof acute diarrhea(per 100,000)
1 to 7 march 2012, France
Source: GP network “Réseau sentinelles”
11
&
Describe: Person = Table
Severe cases of influenza, winter 2011-2012, France
Source: Intensive care units Network
Characteristicsof persons
Burden
12
&
Alert: detect an epidemic
Exceedence
Week
Weekly incidence of flu-like syndromes, 2007-2012, FranceSource: GP network “Réseau sentinelles”
Inci
denc
e (p
er 1
00,0
00)
IncidenceThreshold
13
&
Emergence of W135
0
50
100
150
200
250
300
350
400
450
85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06
années
No
mb
re d
e c
as d
écla
rés
B C W 135 Y
Alert: detect an emerging phenomena
Invasive meningococcal infectionsby serogroup B, C, W135 et Y, 1985-2006, France
Source: InVS, NRC for meningococci
Year
Num
ber o
f cas
es B C W135 Y
14
&
0
20
40
60
80
100
120
140
160
180
200
1940 1950 1960 1970 1980 1990
Année
No
tifi
cati
on
s (x
100
0)C
ou
verture (%)
Evaluate: prevention/control measure
Cases of Pertussis, England and Wales, 1940-1999
Num
ber o
f cas
es (x
100
0)
Year
0
80
40
Vacc
inat
e co
vera
ge (%
)
Vaccinationimplementation
15
&
Evaluate: prevention/control measure
Source: Notifiable disease, InVS Cases of legionellosis, 1988-2011, France
Reinforced surveillanceNew investigation guide
Urine antigen testing
Num
ber o
f cas
es
Year
Inci
denc
e (p
er 1
00,0
00)
No casesIncidence
16
&
Key elements in asurveillance system
17
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
18
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
19
&
Justification of implementation
Ask yourself two main questions:
- Should this event be under surveillance?• High frequency? • High severity?• High socioeconomic cost?
- Do some prevention or control measures exist?
And these two additional questions:
- Do we have existing data that already answer?
- Do we have resources to set up a new system?
20
&
Health events under surveillance
Infectious diseases- Notifiable diseases- Health-care associated infections (HCAI)- Vaccine-preventable diseases- Food and waterborne diseases- Sexually transmitted infections (STI)- Zoonoses- Vector-borne diseases
But also?
21
&
Health events under surveillance
Chronic diseases and injuries: cancers, accidents, traumas, cardiovascular diseases, etc.
Occupational health: cancers, musculoskeletal disorders, respiratory diseases, mental health, etc.
Environmental hazards: air pollution, ionizing radiations, heat/cool waves, water/soil pollution, etc.
22
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
23
&
Objectives of the system
Primary objective: To describe a health-related event in population-based or in a specific population
With two possible aims (sometimes both):
To alert by early detection of epidemics or emerging pathologies that need timely action
To evaluate the efficiency of prevention orcontrol measures
24
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
25
&
Passive and active system
Consideration useful for discussion
Passive: “The data come to you” Data collection based on existing information Simple, not burdensome but could be
incomplete E.g.: notifiable diseases, deaths, emergency data
Active: “You go towards the data” Data collection specially set up Good quality of data but required resources E.g. : injuries, non-notifiable infectious diseases, etc.
26
&
E.g. of passive system
0,0%
0,5%
1,0%
1,5%
2,0%
2,5%
3,0%
3,5%
4,0%
4,5%
S16
S19
S22
S25
S28
S31
S34
S37
S40
S43
S46
S49
S52
S02
S05
S08
S11
S14
2011-2012 2010-2011
% of gastroenteritis among emergency consultations, seasons 2010-2011 and 2011-2012, Aquitaine, France
Prop
ortio
n of
cas
es
Week
27
&
E.g. of active system
Cases of envenomation by Physalia Physalis reported bylifeguards, Aquitaine Atlantic Coast, Summer 2011, France
0
10
20
30
40
50
60
70
80
90
100
1-ju
in //
30-ju
in
4-ju
il.
8-ju
il.
12-ju
il.
16-ju
il.
20-ju
il.
24-ju
il.
28-ju
il.
1-ao
ût
5-ao
ût
9-ao
ût
13-a
oût
17-a
oût
21-a
oût
25-a
oût
29-a
oût
2-se
pt.
6-se
pt.
10-s
ept.
14-s
ept.
18-s
ept.
22-s
ept.
26-s
ept.
30-s
ept.
Période de surveillance
No
mb
re d
e ca
s d
'en
ven
imat
ion
sN
umbe
r of c
ases
Day
28
&
Exhaustive vs. sentinel system
Important consideration for data analysis
Severe diseases or low-frequency diseases requiring timely action
Exhaustive system (= all providers)E.g.: cancers registries, notifiable diseases
High-frequency diseases or less-severe diseases
Sentinel system (= selected providers)E.g.: seasonal flu, occupational diseases (except cancers)
29
&
E.g. of exhaustive system
Cancers among women, Year 2005, Gironde, FranceSource: Cancer
registry of Gironde
Number of cases
1. Breast cancer
2. Colorectal cancer
3. Skin cancer
Can
cer c
ause
s
30
&
E.g. of sentinel system
Prevalence of occupational diseases (except cancers),Year 2010, Region of Aquitaine, France
Male (%) Female (%) Total (%)
Musculoskeletal disorders
3.4 3.5 3.4
Psychic suffering 1.0 2.1 1.5
Skin rashes and allergies 0.3 0.4 0.3
Hearing disorders 0.4 / 0.2
Total 5.2 6.0 5.6
Source: Sentinel Network of occupational physicians (n=92)
31
&
Case vs. syndromic system
Case system (traditional system)
Targets a defined health-related event
E.g.: mesothelioma, Lyme disease, diabetes, etc..
Syndromic system (“before diagnosis”)
For early detection, evaluation of event impact
Based on existing activity data, real-time collection, analysis and interpretation data
E.g.: emergency services, virology labs, deaths certificates, medicine sales, absence in schools, etc.
32
&
E.g. of case system
Occupations at risk for mesothelioma, FranceSource: Program of Mesothelioma Surveillance (1998-2012), InVS
Occ
upat
ions
Odds-ratio (95% CI)
33
&
E.g. of syndromic system
0,0%
0,5%
1,0%
1,5%
2,0%
2,5%
3,0%
3,5%
4,0%
4,5%
S16
S19
S22
S25
S28
S31
S34
S37
S40
S43
S46
S49
S52
S02
S05
S08
S11
S14
2011-2012 2010-2011
% of gastroenteritis among emergency consultations, seasons 2010-2011 and 2011-2012, Aquitaine, France
Prop
ortio
n of
cas
es
Week
34
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
35
&
Case definition
The “heart” of the system!
Must be clear and simple
Based on criteria:clinical, biological, epidemiological
May include:- Classification (possible, probable, confirmed)
- TPP (Time-Place-Person) information
36
&
Source:
Case definitions of notifiable diseases
Commission Decision 2008/426/EC – 28-IV-2008
E.g. for measles definition as notifiable disease
Clinical criteria
Laboratory criteria
Epidemiological criteria
Case classification
37
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart of data and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
38
&
Population under surveillance
Depends on characteristics of health-event
E.g.: Hemolytic Uremic Syndrome (HUS)
- Rare disease that predominantly affects children, needs timely action in outbreak
Population under surveillance (France): children (< 15 years) hosted in pediatric and nephrology hospital services (N=31)
39
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
40
&
Data providers and data sources
Data providers: health professionals, laboratories, health insurance funds, civil status offices, etc.
Data sources
Administrative: death certificates, hospital systems, etc.
Medical: patients folders, notifiable diseases, etc.
Biological: virology, bacteriology, toxicology samples
Environmental: air pollution sensors, individual ionizing radiations card for exposed workers, etc.
41
&
E.g. data provider: NRC (France)
Anaérobies et Botulisme (LA)
Arbovirus (LA)
ATNC
Brucella
Borrelia (LA)
Campylobacter & Helicobacter
Charbon (LA)
Chlamydiae
Cytomégalovirus
Enterovirus
Escherichia coli & Shigella (LA)
Francisella tularensis
Gonocoques
Haemophilus influenzae
Legionella
Leishmania
Mycobactéries et résistance des mycobactéries
Paludisme (2 co-responsables)
Pneumocoques
Résistance aux antibiotiques (LA)
Rickettsia, Coxellia & Bartonella Virus de la rougeole
Staphylocoques VIH
Streptocoques Virus Influenza
Syphilis Virus entériques
Trichinella Virus des hépatites A et E
Toxoplasmose Virus des hépatites B, C et Delta
Arbovirus
Arbovirus & influenza virus en AG
Charbon
Borrelia
Anaérobies et Botulisme
Chimiorésistance du paludisme
en Antilles Guyane
Coqueluche et autres bordetelloses
Corynebactéries toxinogènes
Escherichia coli & Shigella
Fièvres hémorragiques virales
Leptospires
Listeria
Méningocoques
Mycologie et antifongiques
Peste et autres yersinioses
Rage
Salmonella
Résistance aux antibiotiques
Streptocoques (LA)
Virus des Hépatites B & C (LA)
Vibrions et cholera
Virus Influenza
32 NRC and 31 AL
Within hospitals, universities, other research institutes
15 NRCand 3 AL
Pasteur Institute(Paris)
47 National Reference Centers and 34 Associated Laboratories
One NRC perinfectious disease
42
&
E.g. data source: ND (France)
• Botulisme• Brucellose • Chikungunya• Dengue• Fièvres typhoïdes et paratyphoïdes• Hépatite aiguë A• Infections invasives à méningocoques• Légionellose• Listériose• Rougeole• Saturnisme de l’enfant mineur• MCJ et ESST• Toxi-infection alimentaire collective• Tuberculose
• Choléra (RSI)• Diphtérie• Fièvres hémorragiques africaines• Fièvre jaune (RSI)• Paludisme autochtone et paludisme importés
dans DOM• Peste (RSI)• Poliomyélite• Rage• Typhus exanthématique
• Charbon, Tularémie, Variole
• Infection à VIH quel qu’en soit le stade• Hépatite aiguë B• Tétanos
Bioterrorism-related ND (n=3)
Frequent ND (n=14) Infrequent ND (n=10)
27 notifiable diseases (ND) require surveillance and timely action
• Mésothéliome(entrée en 2012)
4 ND require surveillance only
43
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart of data and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
44
&
E.g. French formfor mesotheliomanotiable disease
Anonymous data on patient diagnosis (by clinician&pathologist)
Nominative data on patient and provider
Dates and signatures of provider and sanitary authority
45
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
46
&
E.g. of flow chart: ND (France)
Patient
Health professionals, laboratories, etc.
ReferenceCenters
Experts NetworksClinicians/Pathologists
PartnersNational/International
Public Health High Council
Politic of Health
Alert
Dec
lara
tio
n
Ministry of Health
HealthRegional Agencies
Alert
47
&
Data transmission
Reliable and fast Electronic: e-mails, websites And: phone, fax and mail
Low frequency Daily Weekly Monthly
Secure Regularity, punctuality, exhaustiveness And don’t forget the “Zero reporting”
48
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
49
&
Data validation and data analysis
Data validation Missing data Duplicates Data quality
Data analysis Indicators: frequency, severity Methods: descriptive, analytical Illustrations: tables, graphs and maps Keep in mind: Time-Place-Person!
50
&
Daily deaths, summers 1999-2002 vs. 2003, France
E.g. of data analysis: time series
0
50
100
150
200
250
300
350
25-juin 30-juin 05-juil 10-juil 15-juil 20-juil 25-juil 30-juil 04-août 09-août 14-août 19-août
Décès journ
alie
rs
0
5
10
15
20
25
30
35
Tem
péra
ture
(°C
)
Décès 1999_2002 Décès 2003 T moy 1999_2002 T moy 2003
Num
ber o
f dea
ths
Day (25 June to 19 august)
Source: Syndromic Program, InVS
Tem
pera
ture
(°C
)
Temperature
Deaths
1999-2002
2003
1999-2002
2003
51
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
52
&
Dissemination/communication data
Systematic and regular For stakeholders, decisions makers For other professionals, public, medias
Adapted To “Those who need to know” To the urgency of the situation
Format Report, article, flash news, press release etc. But also: phone, e-mail, fax, mail
Factor of motivation/improvement
53
&
E.g. report at local level
“Point épidémio”
France, Bordeaux(InVS, south west)
Weekly report on health status of population
Topics:
OutbreaksSeasonal pathologiesNotifiable diseasesVirology surveillanceDeaths
54
&
E.g. report at international level
WHO (Switzerland)
CDC (USA)
55
&
E.g. press release
At international level (e.g. Europe)
At local level(e.g. France, Bordeaux)
56
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
57
&
Human and financial resources
From the budget to the expenses Salaries, travels, equipments, furniture, etc. Useful to negotiate resources, check the
workplan, assess the cost of the system
58
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
59
&
Data security and confidentiality
“Critical point” in surveillance system
Public heath data
Often personal and private in nature Might directly identified individuals
Take into account policiesand protection forpersonal data
Data collectionoften under laws
60
&
Key elements
Justification of implementation Objectives of the system Types of system Case definition Population under surveillance Data providers and data sources Data elements and data collecting tools Flow chart and data transmission Data validation and data analysis Dissemination and communication data Human and financial resources Data security and confidentiality Evaluation of system
61
&
Aims of evaluation
Ask yourself the fundamental question:
Have the objectives been met?
And these additional questions:- Did the system generate needed answers?
- Was the information timely?
- Was it useful for decisions makers?
- How was the information used?
- What could be done to improve the “attributes”?
- Is it useful to continue the surveillance?
62
&
Simplicity: refers to structure and ease operation
Flexibility: ability to adapt to changing needs
Data quality: refers to data completeness&validity
Acceptability: willingness of persons and organizations to participate
Sensitivity: refers to proportion of detectedcases by the system (“A / A + C”)
The “9” attributes of a system (1)
63
&
PVP: refers to proportion of reported the cases that actually have the event (“A / A + B”)
Representativeness: ability to describe the event over time and its distribution in the population
Timeliness: reflects the speed between system steps of the system
Stability: refers to reliability and availability
The “9” attributes of a system (2)
64
&
Conclusion
65
&
Main messages
Justification- Relevance of the event to be under surveillance- Existence of prevention and control measures
Objectives and aims To describe – To alert – To evaluate To produce information for action In order to reduce morbidity and mortality
Requirements- “Good data”, involvement of stakeholders- Regular evaluation of the system
66
&
One useful book
3rd edition
September 2010
Lisa M. Leeet al.
67
&
Don’t forget the surveillance loop!
Data collection
Data analysis
Information
Action!
Evaluation
Objectives
68
&
Le fil rouge in surveillance?
Surveillance isInformation for
action!