1. Surveillance James Westwood Public Health Information Analyst Knowledge and Intelligence Team, South West

2. Objectives 1.To gain an understanding of what is meant by the term ‘surveillance’ 2.To identify the drivers, purpose and applications of surveillance (i.e. why do we do it?) 3.To describe the attributes of a surveillance system 4.To look at some of the methods of interpreting surveillance information 2

3. 1. What is meant by the term ‘surveillance’? Discussion: What does the term mean to you? Basic definition: a watch kept over a person, group, etc. What about surveillance for Public Health / Healthcare? 3

4. A definition: Public Health surveillance is the on-going systematic collection, analysis, interpretation and dissemination of data regarding a health related event for use in public health action to reduce morbidity mortality and improve health (CDC, USA) Useful link: http://publichealthobserver.com/definition-of-surveillance-system/http://publichealthobserver.com/definition-of-surveillance-system/ 1. What is meant by the term ‘surveillance’? Different types or methods of surveillance 4

5. Special effort is made to collect the data, confirm diagnoses and could include searches to find additional cases in communities. Formal and informal communications between those collecting the data and those required to send it will occur. e.g. Healthcare Associated Infections (HCAI) http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/HCAI/ Passive surveillance 1. What is meant by the term ‘surveillance’? Active surveillance This uses routine sources of information without additional effort to identify cases not identified by usual mechanisms (meaning healthy carriers or cases that are not severe enough to be seen in a healthcare setting remain in circulation) e.g. Syndromic surveillance http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/RealtimeSyndr omicSurveillance/ 5

6. Enhanced surveillance 1. What is meant by the term ‘surveillance’? In cases where normally collected surveillance information is not enough, take an additional step of collecting more in depth information e.g. Enhanced Tuberculosis Surveillance, ETS http://www.hpa.org.uk/web/HPAweb&Page&HPAwebAutoListName/Page/129 4739536811 http://www.hpa.org.uk/web/HPAweb&Page&HPAwebAutoListName/Page/129 4739536811 Sentinel surveillance A sentinel surveillance system is used when high-quality data are needed about a particular disease that cannot be obtained through a passive system. Selected reporting units, with a high probability of seeing cases of the disease in question identify and notify on certain diseases. e.g. QSurveillance http://www.qsurveillance.org/QSurveillance/Home_Page.html http://www.qsurveillance.org/QSurveillance/Home_Page.html Useful link: http://www.who.int/immunization/monitoring_surveillance/burden/vpd/surveillance_type/sentinel/en/ http://www.who.int/immunization/monitoring_surveillance/burden/vpd/surveillance_type/sentinel/en/ 6

7. 2. Why do we do surveillance? Information & Analysis Build information on the temporal, geographic and population distribution and epidemiology of new, poorly understood and well understood diseases e.g. Measles notifications: 1954: 146,995 2013: 6,102 England & Wales 1940 - 2013 i.e. is the occurrence of disease, risk factors or microbial agents changing over time? 7

8. 2. Why do we do surveillance? Helps Public Health professionals to.. Inform decision making for public health, health service planning, risk management, research and control priorities Inform key disease eradication or control programs Inform the public about the risks to individuals and the general public Provide information to support the development of guidance for professionals on the clinical management of individual patients, the choice of the appropriate control strategy and the organisation of services to deliver them to those at risk Ensure that the UK makes its full contribution to European and International efforts to protect health Information & Analysis 8

9. 2. Why do we do surveillance? Monitor the use and coverage of an intervention, any adverse events arising from that intervention and the overall impact of disease control measures (including immunisation) Describe the basic epidemiology and/or natural history of a disease or condition to develop research hypotheses that can be tested in studies Information & Analysis Detection & Action Inform the development of policies to detect new threats and emerging problems, to reduce exposure to a particular hazard or to protect individuals in advance of such exposure 9 Detect changes in disease or condition patterns that indicate changes have occurred Enable appropriate and timely action to be taken in order to protect the public health

10. Case Definition / Core data: Time, Person, Place (TPP) 3. Attributes of a surveillance system 10 Data Collection Data Source(s) Frequency/Method of reporting Electronic? Paper? Oral? Daily? Weekly? Monthly? Quarterly? Notifications, Lab reports, Hospital data (SuS / HES), GP systems, Vaccinations, Etc. PHE communicable diseases surveillance system: Second Generation Surveillance System (SGSS)

11. Timeliness or Accuracy? Where should the emphasis lie? 11 3. Attributes of a surveillance system Depends on the system and / or desired outcomes e.g. Statutory Notifications - Suspicion of disease based on clinical signs enough to require reporting e.g. measles / scarlet fever (list of about 30 diseases) -Do not require lab confirmation -NOIDs dataset (notifications of infectious diseases) -Legal requirement to report, failure carries a fine -Emphasis on outbreak prevention / disease spread Hospital Episode Statistics -More processing of data (de-duplication, error checking, validation) -Less timely, not released ‘in real time’ -Target audience: national bodies and regulators, local commissioning organisations researchers and commercial healthcare bodies -Uses include: basis for national indicators of clinical quality, monitor trends, support local service planning -Emphasis on accuracy and quality rather than immediate availability

12. 12 3. Attributes of a surveillance system Evaluation of a surveillance system --- Simplicity (Structure and ease of operation) --- Flexibility (adapt to changing information needs) --- Data quality (completeness and validity) --- Acceptability (engagement of participants) --- Sensitivity (detection of cases, detection of outbreaks) --- Representativeness (accurate description of events by TPP) --- Timeliness (speed between steps e.g. health event and reporting of event) --- Stability (reliability and availability of system) Useful link: http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5013a1.htm,http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5013a1.htm Morbidity and Mortality Weekly Report (MMWR)

13. 13 3. Attributes of a surveillance system Legal and ethical issues Must comply with rights for individuals e.g. Data Protection Act 1998, Human Rights Act 1998, Caldicott Guidelines 1997. Patient identifiers (PID) often needed for: de-duplication follow up (if required for communicable diseases) outbreak investigation geographical analyses (including associations between environmental factors) dataset linkage Right to collect PID The Health Service Regulations 2002 provide legal basis for PID data handling. NHS Act 2006 allows NHS organisations to disclose PID to PHE without explicit consent of the patient. Use of data is subject to agreed activities as approved by National Information governance Committee (permission reviewed and applied for annually)

14. 14 4. Methods of interpretation Considerations before beginning analysis 1.What is the primary purpose? (have a specific question in mind e.g. has there been a systematic change in incidence of MRSA in Trust X) 2.What data are you going to use to achieve the primary purpose? (counts of MRSA surveillance data from Trust X from time period A to time period B) 3.Does the data have any obvious deficiencies? (only bacteraemia not all MRSA infections, population stability? Do we need to calculate rates for a measure of standardisation? Changes in testing / lab techniques?) 4.Visualise the time series (plot a graph of the data over the period as a starting point)

15. 15 4. Methods of interpretation Considerations before beginning analysis Understand the data you are analysing: Completeness of reporting Modifications to the surveillance system (can impact reporting of cases and trend analyses) Quality of data Other factors (e.g. reporting delays if you’re doing real-time or near real-time analysis)

16. 16 Assessing trends in time-series 4. Methods of interpretation 1. Visualising and describing The human brain is particularly good at detecting patterns so it is always important when visualising a time-series to describe what you are seeing

17. 17 Assessing trends in time-series 4. Methods of interpretation 2. Control charts (SPC) SPC (statistical process control) charts are reasonably frequently used to prospectively monitor whether a “process” is in control Useful link: Technical briefing 2: http://www.apho.org.uk/resource/item.aspx?RID=39306http://www.apho.org.uk/resource/item.aspx?RID=39306 Idea is to try and differentiate between ‘common cause’ variation and ‘special cause’ variation. The assumption is that variation is inherently present in any system Uses ‘rules’ to aid in interpretation

18. 18 Assessing trends in time-series 4. Methods of interpretation 3. Cumulative sums (CUSUM) Can use simple cumulative sum charts such as the VLAD chart to describe the running total of excess or prevented cases of disease over time. Calculate the difference in each time period of the observed number of cases and the expected number of cases Calculate the running total i.e. d1, d1+d2, d1+d2+d3, etc Plot these cumulative sums over time. Other methods (regression etc.)

19. The End! 19