Principles of Surveillance

1. Principles of Surveillance Lazareto de Mahón, Menorca, Spain 13th October 2009 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. Aim 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

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. First use of data for Public Health Action 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

9. Definition by Alexander Langmuir (1910 – 1993) “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”

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

11. Aims of Surveillance • 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

12. Examples for Interventions • 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

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

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

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

18. 1. Understand the problem - Criteria for priority setting Public Health importance • 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

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

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

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

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 - life births (CRS) - bacterial isolates (AMR)

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

27. 5. Design – data set • 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

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 What does who need to know? 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. Challenges • 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

37. Opportunities • 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

38. Summary • Context • communicable disease control • epidemiology • Definition • 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