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Principles of Surveillance Lazareto de Mahón, Menorca, Spain 11 October 2011 Katharina Alpers (2009), Martin Donaghy (2008), Susan Hahné (2007, 2006),

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Presentation on theme: "Principles of Surveillance Lazareto de Mahón, Menorca, Spain 11 October 2011 Katharina Alpers (2009), Martin Donaghy (2008), Susan Hahné (2007, 2006),"— Presentation transcript:

1 Principles of Surveillance Lazareto de Mahón, Menorca, Spain 11 October 2011 Katharina Alpers (2009), Martin Donaghy (2008), Susan Hahné (2007, 2006), Suzanne Cotter (2005), Denise Werker (2004)

2 Content aim of lecture surveillance: context, definitions and history aims of surveillance the process surveillance versus research steps in setting up surveillance criteria for undertaking surveillance challenges & opportunities summary

3 After the lecture, you should be able to… Define: surveillance its three main components Describe: the contexts / historical perspective of surveillance possible aims criteria for undertaking surveillance the difference between surveillance and research the different steps in setting up surveillance some challenges and opportunities Aim

4 Intervention Epidemiology Surveillance Outbreak investigation Applied epidemiological research

5 Surveillance in EPIET Introductory Course Lectures Principles of surveillance Event-based surveillance Analytical tools in surveillance Evaluation of a surveillance system H1N1 surveillance in Europe Case studies Implementation of H1N1 surveillance Surveillance data analysis Evaluation of surveillance systems

6 The Concise Oxford Dictionary n. Close observation, especially of a suspected spy or criminal ORIGIN French, from sur- 'over' + veiller 'watch' Source: The Concise Oxford Dictionary. Ed. Pearsall J. Oxford University Press, 2001.

7 Tools for Control of Communicable Diseases isolation treatment vaccination prophylaxis disinfection quarantine surveillance Close observation of individuals suspected of incubating serious infectious diseases in order to detect initial symptoms of disease in time to institute treatment and isolation

8 William Farr (1807 – 1883) Superintendent of statistical department, General Register Office, England and Wales Collected, analysed, interpreted vital statistics Described epidemics of infectious diseases Drew conclusions, made recommendations Disseminated information First use of data for Public Health Action

9 Continued watchfulness over the distribution and trends of incidence, through the systematic collection, consolidation and evaluation of morbidity and mortality reports and other relevant data together with the timely and regular dissemination to those who need to know Definition by Alexander Langmuir (1910 – 1993)

10 Systematic collection of pertinent data Orderly consolidation and evaluation of these data Prompt dissemination of the results to those who need to know 21st World Health Assembly (1968) " Information for action"

11 Assess public health status (monitor trends, detect outbreaks) - prevent and control disease Define public health priorities - plan considering impact of hazard, exposure, disease Evaluate public health programmes - take decisions regarding interventions Stimulate or inform research - generate hypotheses, inform methodologie Aims of Surveillance

12 manage contacts of a case detect outbreaks early warning design/change vaccination policy design policy re antimicrobial resistance evaluate interventions to improve them certify elimination / eradication Examples for Interventions

13 Health Care SystemPublic Health Authority Event Data Information Intervention Reporting Capture Analysis & Interpretation Real world! … expected changes Dissemination Surveillance is a cyclical process

14 Surveillance versus Research Surveillance Applies existing knowledge to guide health authorities in the use of known control measures Directly relevant to monitoring and control needs Research Pursues new knowledge from which better control measures will result Systematic investigation, testing and evaluation, designed to develop or contribute to knowledge

15 What we have seen so far Contexts of surveillance Historical perspective Definitions Aims Three main components Surveillance versus research

16 1.Understand the problem 2.Identify opportunities for prevention & control - interventions - target audience 3.Set objectives 4.Specify attributes to meet objectives 5.Design - case definitions & indicators - data needed - data sources - data transfer Steps in setting up surveillance (1)

17 6.Translate information into action - analyse - interpret - disseminate 7.Evaluate surveillance system Steps in setting up surveillance (2)

18 burden of disease (incidence / prevalence) severity, mortality epidemic potential, threat costs, socio-economic impact preventability / opportunities for control intervention programme in place public concern and news-worthiness Feasibility costs availability of data 1. Understand the problem - Criteria for priority setting Public Health importance

19 Infection Disease Death Disability Recovery Source infection Transmission Reservoir 3. Treatment 2. Prophylaxis 6. eg. hygiene precautions, vector control 5. Ecological Management Exposure 1. Vaccination 2. Opportunities for intervention 4. Isolation/ treatment

20 Public Health professionals Government / Politicians Clinicians / Microbiologists / Control of Infection staff Environmental Health professionals Health service managers Health educators / teachers NGOs Public 3. Target audiences

21 Specific Measurable Acceptable and Action oriented Realistic Time related 3. Set objectives SMART

22 3. Set objectives - examples Vague... To estimate the prevalence of hepatitis C To detect outbreaks of measles Specific, measurable, action-oriented & timed To assess the prevalence of hepatitis C in France in order to allow planning of specific health care needs for the coming 20 years To detect early time and place clustering of measles cases in order to ensure timely control of outbreaks

23 4. Attributes of the system Timeliness Sensitivity Specificity Completeness of information Representativeness Acceptability Keep it as simple as possible!!

24 Sentinel vs. comprehensive Aggregated vs. individual data Active vs. passive Statutory vs. voluntary Confidential vs. anonymous Basic vs enhanced Indicator based versus event based Security 5. Design – options

25 5. Design – examples of data needed Numerators - number of cases - number of resistant strains Denominators - population under surveillance - live births (CRS) - bacterial isolates (AMR)

26 5. Design – case definitions Exposed Clinical specimen Symptoms Lab confirmed Infected Seek medical attention Report

27 Case Definition -Confirmed – Positive laboratory result -Probable – Clinical + epidemiological link to confirmed case -Possible - Clinical symptoms and signs Demographics -Person, place and time Risk Factors -Exposures -Behaviours Administrative -Time reported -Source 5. Design – data set

28 5. Design – issues cost representativeness comparability confidentiality acceptability data quality timeliness commercial sensitivity

29 5. Design – data sources: health services –Laboratories: frontline diagnostic, reference –Clinical services: physicians, hospital discharge data, disease registries –Screening programmes (antenatal, blood donors) –vaccination programmes –pharmacy / over the counter drugs

30 5. Design – other data sources Veterinary –animals (domestic, wild) –food Environment –water –food –air Population statistics –deaths –denominators

31 5. Design – data transfer Existing infrastructure Methods –Paper –Telephone –Electronic –Web-based Frequency Zero reporting

32 Analysis –descriptive (time, place, person) –analytical –time series –outbreak detection –molecular epidemiology –geographical information systems (GIS) Interpretation –system and data characteristics and changes –chance, bias, truth –Public health significance 6. Information for Action (1)

33 Dissemination of information –develop outputs in consultation with users –Who needs to know what? –timing –appropriate level of detail –regular review of usefulness –avoid information overload 6. Information for Action (2)

34 6. Dissemination of information Alerts -National and local -Europe: EWRS -International: IHR Reports -Bulletins -Annual statements -Scientific journals Internet Public -media

35 Does the system do what it set out to do? i.e. meet specified objectives: Contribute to achieving public health goals? Meet the needs of stakeholders to improve policy, services, public understanding? 7. Evaluation of surveillance system

36 Surveillance or research needed? Reliability –crude and inaccurate –incomplete –accurate denominators Sustainability –victim of success of control New threats –emerging infections –bioterrorism Timeliness Human Rights / data protection Challenges

37 Near patient testing Less invasive diagnostics (oral fluid, urine) New molecular typing methods Electronic patient records New data sources Behavioural surveillance Syndromic surveillance On-line, web-based systems –data entry –dissemination of information ´New´ analysis methods –GIS –bio-informatics –modelling Opportunities

38 Context –communicable disease control –epidemiology Definition –systematic collection of data –information for action Aims Process with 3 components –capture –analysis –dissemination Difference between surveillance and research Criteria and steps to set up surveillance system –public health importance –feasibility –information for action Challenges and opportunities Summary

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