Introduction to Surveillance

1. Introduction to Surveillance

2. Questions • What do you think of when you hear the word “surveillance”? • What do you suppose is the definition of surveillance when applied to infection prevention and control?

3. Learning Objectives • Define surveillance and its role in an infection prevention and control program • Describe types of surveillance and advantages and disadvantages of various surveillance strategies • Give examples of basic measures of disease frequency and describe applications

4. Public Health Surveillance Definition The ongoing, systematic collection, analysis, and interpretation of health-related data essential to the planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination of these data to those responsible for prevention and control

5. Surveillance in the Healthcare Setting • Surveillance of healthcare—acquired infections (HAI) is the foundation for organizing, implementing, and maintaining an effective infection prevention and control (IPC) program in the health care facility • “If you don’t measure it, you cannot improve it” ~ Lord Kelvin

6. Considerations for Surveillance • Frequency • Severity • Cost • Preventability • Communicability

7. Methodologic Issues • Goals • Causal pathway • Information needs • Data sources, methods • Case definition • Evaluation: Balance of attributes • Interpretation of data

8. Interpretation of DataIssues to Consider • Source of data • Reliability of diagnosis • Potential biases in detection/diagnosis • Definition of a case • Completeness of data • Reporting bias • Consistency in data collection • Completeness • Context

9. Surveillance in the Healthcare Setting:Objectives • Establish endemic or baseline rate of infections • Compare HAI rates within/between health care facilities • Engage clinical team to adopt best practices • Introduce evidence-based and cost-effective interventions to reduce HAI • Identify and control outbreaks • Evaluate success of the ICP interventions • Identify priority areas to allocate resources Ultimate aim is to reduce HAI

10. Components of a Strong Surveillance Program • Systematic • Ongoing • Data Collection • Analysis • Interpretation • Dissemination • Action

11. Surveillance in the Healthcare Setting • Data must be • Collected • Validated • Analyzed • Interpreted • Disseminated in a timely manner • Collecting and recording data is useless if no further action is taken • Surveillance is synonymous with the premise of “information for action”

12. Surveillance in the Healthcare Setting:Methods When applicable, data set should include: • Information on the infected patient or resident • Information on medical treatment or procedures at the time of infection • Any underlying medical risk factors of the patient Information on both numerator and denominator data should be collected for the calculation of rates of infection

13. Surveillance in the Healthcare Setting:Methods • Flexible to address challenges • Technological changes within the health care facility • Short lengths of stay • Healthcare worker shortage and turnover • Increased frequency of invasive procedures or devices • Post-discharge surveillance, as appropriate

14. Characteristics of a Strong Surveillance Program • Targets • Infection prevention • Performance improvement • Patient safety • Public health activities • Engages in mandatory and public reporting

15. Characteristics of a Strong Surveillance Program • Able to identify risk factors for infection • Adverse events • Outbreaks • Emerging infectious diseases • Antibiotic-resistant organisms • Bioterrorist events • Implements control or risk-reduction measures • Monitors the effectiveness of intervention

16. Various Methods of Surveillance Used in Infection Control Adapted from: Glenister HM, Taylor LJ, Bartlett CLR, et al. An evaluation of surveillance methods for detecting infections in hospital inpatients. Journal of Hospital Infection 1993; 23:229-42.

17. Various Methods of Surveillance Used in Infection Control

18. Various Methods of Surveillance Used in Infection Control Adapted from: Perl TM, Chaiwarith R. Surveillance: An overview. Practical Healthcare Epidemiology, 3rd Ed., pp. 111-142, Chicago, IL: University of Chicago Press, 2010.

19. Types of Surveillance: Outcome Surveillance • Objective: COUNT number of HAI • Informs the magnitude of the problem Disadvantages: • No information on what factors contribute to the problem • No internationally agreed definitions on surveillance • Most commonly used: CDC/NHSN (USA) and ECDC (Europe) • Assumes availability of good diagnostic laboratory support

20. Types of Surveillance: Process Surveillance • Objective: MONITOR adherence to evidence-based or best practices • Essential to prioritize which processes/steps to monitor Disadvantages: • Reliability of data • Good compliance does not equate with effectiveness

21. Example of Outcome vs. Process Surveillance PROCESS SURVEILLANCE OUTCOME SURVEILLANCE Counting number of CR-BSIs Monitoring compliance with CVC care bundle elements Adapted from Damani, N. Manual of Infection Prevention and Control, Third Edition. New York: Oxford University Press, 2012.

22. Recommended Minimum Elements in a Data Set for Surveillance • Patient /resident information • Name or unique identifier, DOB, sex, MRN, ward or unit in facility, name of consultant, date of admission, onset date, date of discharge or death, site of infection/colonization, organism isolated with antibiotic sensitivities • Medical treatment/procedures • At time of infection • Underlying medical risk factors, clinical outcome, assessment of whether the incident was preventable

23. Linelist: Example

24. Considerations • All types of surveillance are expensive and time-consuming • Essential that definitions and objectives of surveillance must be agreed with the clinical team • Identify resources • Personnel involved in surveillance must be trained

25. Summary • Assess population and identify those at greatest risk for outcome or process of interest • Select outcome or process for surveillance • Examples of outcomes: HIA, infection or colonization with a specific organism, sharps injuries • Examples of processes: Central line insertion practices, influenza vaccination rates, personnel compliance with protocols • Determine observation period

26. Summary (continued) • Choose surveillance methodology • Monitor for outcome or process using standardized definitions for all data collected • Collect appropriate denominator data, if rates are to be calculated • Analyze data • Report in a timely manner

27. References Damani, N. Manual of Infection Prevention and Control, Third Edition. New York: Oxford University Press, 2012. DHHS/CDC . Outline for Healthcare-Associated Infections Surveillance, 2006. Tokars JI, Richards C, Andrus M, et al. The Changing Face of Surveillance for Health Care—Associated Infections. Clinical Infectious Diseases 2004; 39: 1347-52. Horan TC, Andrus M, Dudeck MA. CDC/NHSN surveillance definition of health care—associated infection and criteria for specific types of infection in the acute care setting. American Journal of Infection Control 2008; 36:309-32. Haley RW, Culver DH, White JW, et al. The efficacy of infection surveillance and control programs in preventing nosocomial infection in US hospitals. (SENIC study). American Journal of Epidemiology 1985; 121(2):182-205. Lee TB, Montgomery OG, Marx J, et al. Recommended practices for surveillance: Association for Professionals in Infection Control and Epidemiology (APIC), Inc. American Journal of Infection Control 2007; 35(7):427-40. HICPAC guidance on public reporting of healthcare-associated infections: Recommendations of the Health care Infection Control Practices Advisory Committee. Infection Control Hospital Epidemiology 2005; 26(6):580-7.

28. “Good surveillance does not necessarily ensure the making of right decisions, but it reduces the chances of wrong ones.” -Alex Langmuir, NEJM 1963: 268:182-191

29. MEASURES OF DISEASE FREQUENCY

30. “One’s knowledge of science begins when he can measure what he is speaking about and express it in numbers” Lord Kelvin 1824-1907

31. Measures in General • Count • Ratio • Proportions • Rate

32. EPIDEMIOLOGIC MEASURES Measures of frequency • Incidence • Prevalence • Interrelationship between incidence and prevalence

33. COUNT Simple measure of quantity Example: The number of catheter-related bloodstream infections (CR-BSIs) in Facility X in 2012.

34. RATIO An expression of the relationship between a numerator and a denominator where the two are separate and distinct quantities. Example: Injurious falls occur in twice as many women aged 65-69 years as in men of the same age group. Ratio of women to men is 2/1 or 2:1

35. PROPORTION A type of ratio in which the numerator is included in the denominator.

36. EXAMPLE OF PROPORTION • 650 HIV+ patients were seen at Facility X. • 130 of these patients had Pneumocystis cariniipneumonia (PCP). • Proportion of HIV+ patients seen at Facility X with PCP is 130/650. • 130/650 *100 = 20%

37. RATE An expression of the frequency with which an event occurs in a defined population. A measure of time is an intrinsic part of the denominator.

38. EXAMPLE OF RATE 435/1,000 elderly individuals residing in assisted living facilities had colds in January. (The 435 elderly residents with colds are part of the 1,000 residents in assisted living facilities.)

39. TYPES OF RATES Morbidity rates measure the frequency of illness within a specific population. • Incidence • Prevalence • Attack rate Mortality rates measure the frequency of death within a specific population. • Crude death rate • Cause-specific death rate • Case-fatality rate

40. MEASURES OF DISEASE FREQUENCY Measures that characterize the occurrence of disease, disability or death in populations. • Incidence • Prevalence

41. Measures of Disease Frequency • Incidence (I): Measures newcases of a disease or health event that develop over a period of time. • Prevalence (P): Measuresexistingcases of a disease at a particular point in time or over a period of time.

42. INCIDENCE The number of new cases of disease that occur in a specified period of time. There are two kinds of incidence measures: • Cumulative incidence (CI) • Incidence density (ID) or incidence rate (IR)

43. CUMULATIVE INCIDENCE The proportion of unaffected individuals who contract disease during a specified time. CI = # of new cases in a given time Total population at risk (Estimate of individual risk)

44. Problems with using CI • To accurately calculate CI we need to follow the entire populationfor thespecifiedtime interval. • This is rarely possible for two main reasons • People move in and out • People may die from diseases other than disease of interest

45. INCIDENCE RATE The instantaneous potential for change in disease status per unit of time. IR = # new case in a given time Total person-time of observation Ranges from 0 to 

46. What denominator data to collect? For device-associated HAI incidence rates: • Daily total number of patients AND • Total number of ventilator-days, central line-days, and urinary catheter-days in patient care area(s) under surveillance • Sum daily counts at the end of the surveillance period for use as denominators Denominator data may be collected by someone other than the ICP as long as that person is trained

47. INCIDENCE RATE EXAMPLE Three people out of ten persons observed develop disease during a 30-day period of follow-up. The cumulative rate = 3 cases in 30 days 10 people or 1 per 100 per day (3/10 = 0.3 * 100 = 30/30 days = 1 = incidence for one day per 100 people)

48. ATTACK RATE • Another type of incidence rate • Expressed as cases per 100 population (or a percentage) • Used to describe the new and recurrent cases of disease that have been observed in a particular group during a limited time period in special circumstances, such as during an outbreak • Attack rate: Number of new and recurrent cases in a specified time period Population at risk for same time period X 100

49. Prevalence • Measures existing cases of a health condition • Two types of Prevalence • Point prevalence • Period prevalence

50. Point Prevalence • Point Prevalence = C / N Where C = Number of observed cases at time t And N = Population size at time t Point prevalence measures the frequency of disease at a given point in time.