Epidemiological Surveillance

Transcription

1 Faculty of Medicine Introduction to Community Medicine Course ( ) Unit 4 Epidemiology Introduction to Epidemiology Sources of Data and methods of data collection Epidemiological Surveillance By Hatim Jaber MD MPH JBCM PhD

2 Introduction to unit 4 Epidemiology Definition, History of Epidemiology Purpose/Use of Epidemiology Concepts in the infectious diseases Disease Causation Measurements of Morbidity and Mortality Levels of prevention and vaccination Screening for diseases and vaccination Sources of Data and methods of data collection Epidemiological Surveillance Epidemic Investigation and Management 2

3 World Antibiotic Awareness Week Antibiotics: Handle with care Date: 14 to 20 November

4 Presentation outline Time Introduction and Definitions 12:00 to 12:10 Sources of data 12:10 to 12:20 Methods of collecting data 12:20 to 12:30 Routine and non routine health data/information Epidemiological Surveillance 12:30 to 12:50 Next lecture 4

5 Objectives Identify data and the sources for health information Describe the advantages and disadvantages of each source Define what is a health information system (HIS) and understand its components Describe the methods of data collection Define routine health data/information Discuss routine data collection methods Define non-routine data Discuss methods of collection for non-routine data 5

6 Real world FROM REALITY TO ACTION Data (Collection, coding) (Processing, interpretation, presentation) Information (Politics, commitment) Action Source: Oxford Handbook of Public Health Practice 6

7 Definitions and USE OF WORDS DATA, INFORMATION & Knowledge: DATUM (singular) or DATA (plural) refers to raw numbers or other measures, usually discrete and gives objective facts about events. Data: the raw facts that are collected and form the basis for what we know INFORMATION refers to what emerges when data are processed, analyzed, interpreted and presented. - Information is data transformed (contextualized, categorized, corrected, calculated, condensed) into a message Information: the product of transforming the data by adding order, context, and purpose Knowledge: the product of adding meaning to information by making connections and comparisons and by exploring causes and consequences 7

8 Definitions cont.. data means an organized collection of individual measurements for each subject, in respect of every variable of interest. Once this data has been collected, collated and summarized it is called Information. Thus, information is a factual presentation i.e. a Summary of facts from the data and as they exist without any added element of interpretation of facts. 8

9 Why do programs need information? Management level: Community - patient - facility system Health-system function: Service delivery - resource mobilization - financing stewardship Health determinant: Health care - lifestyle - environment Information is needed to: (1) understand the program status in all its complexity; (2) enhance program performance through evidence-based decision making for all major functions (service delivery - resource mobilization - financing - stewardship) at all levels (from community to national level)) 9

10 Definitions Health system all resources, organizations and actors that are involved in the regulation, financing, and provision of actions whose primary intent is to protect, promote or improve health. (WHO, 2000) Program A set of procedures to conduct activities. The objective is normally the solution to a problem Neither a health system or program is a static phenomena. They experience a continuous process of changes due to pressure from both outside the system and from within the system. 10

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12 Definitions Health Information System (HIS): A health-information system (HIS), similar to a health management information system (HMIS) a system that provides specific information support to the decision-making process at each level of an organization (Hurtubise, 1984) Data Systems a way of talking about the whole set of M&E indicators in a performance monitoring-and-evaluation plan, and all of the data and other information that need to be gathered and understood in an orderly fashion that makes sense and help in program management and implementation 12

13 Routine TYPE The Health Information System: Data for Planning, Monitoring and Evaluation USE Non-Routine National Level District Level Facility/ Client Aggregated Service Statistics Aggregated Mgmt Data Aggregated Surveillance Data Financial Data Vital Registration Systems Aggregated Service Statistics Aggregated Mgmt Data Sentinel Sites Observation Checklist Self-Evaluation (e.g. COPE) Client Records Financial Records Supply Records Facility logbooks/data records Aggregated Community Data Policy-Making Strategic Planning Program Tracking Disease Surveillance Technical & Logistical Support Planning (Access) Management (Quality/Efficiency) Supervision (Performance) Disease Surveillance Client Mgmt and Follow-Up Health Unit Management Work Planning/Priority Setting Rapid Assessment Methods Population-based surveys e.g. DHS Facility-based surveys e.g. Situation Analysis, SPA Special Studies e.g. EPI cluster surveys, KAP studies, etc. Census Community Birth and Death Records School Records CBD logbooks Drug Revolving Fund records Client Mgmt and Follow-up Supplies Management Community Awareness 13

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15 HIS subsystems or information systems Tools or HIS subsystems or information systems: are The various data collection and processing mechanisms that comprise a health information system Epidemiological surveillance for notifiable infectious diseases, certain environmental conditions, and risk factors; Routine service reporting from the basic health services at community level, health centers, dispensaries, first-level hospitals, referral hospitals, and special and tertiary hospitals; Special program reporting systems such as Tuberculosis Control, Leprosy Control, Malaria Control, Maternal and Child Health and Family Planning, Expanded Program on Immunization, and HIV/AIDS prevention; Administrative systems including health-program budget management, health-financial systems, health-personnel systems, health supply and logistic systems, health-training programmes, health-research management, health-documentation management, and managing external health resources for health; and Vital registration of births, deaths, and migration. Demographic: Population 15

16 Minimum Information required by a Public Health Specialist in most Settings General Information : Location, Governmental and Societal patterns, geographical and topographical features, roads & other communications, languages, physical and climatic characteristics of the block / district. Socio - demographic profile : Population size, age & sex constitution, distribution of population in different areas of the district, fertility indicators, growth rate, education, occupations and economic strata. Morbidity and Mortality : Incidence or prevalence of mortality, morbidity and diseases with epidemic potential; demographic indices as infant mortality and maternal mortality rates. Health Related indicators : water supply, disposal of excreta, housing patterns, food availability. Health Services : Strength and location / distribution of various categories of health care personnel, governmental and non - governmental; availability, location and adequacy of health care supplies, equipment and other logistics. Preventive / Promotive Health programs : Availability, locations and 16 adequacy of major programs as immunization, HIV - AIDS / TB

17 Types of Information Surveillance Epidemiological Behavioral Routine service reporting Special program reporting systems Administrative systems Vital registration systems Facility surveys Household surveys Censuses Research and special studies 17

18 Frequency of Data Collection ROUTINE or continuous data collection Health facility-based (patient information and service statistics) Community-based (service-statistics) Program-based (administrative) Vital registration Sentinel reporting/demographic surveillance NON-ROUTINE or periodic data collection Household or facility-based surveys Population census Rapid-assessment procedures (RAP) Special studies/research 18

19 Geographic System Levels National Sub-national (e.g. district) Program area 19

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22 I. Sources of Data There are different sources of data on health and health related conditions in the community. Each source has advantages and limitations. The information obtained from these sources is used for health planning, programming and evaluation of health services. The major sources are the following. 22

23 Data Sources: Population Census Vital registration system Sample household surveys Special population surveys - Demographic (elderly, youth) - Risk groups ( IDUs) - Occupational (farmer, skilled labor) - Area-based (catastrophe-affected) Biomarkers 23

24 1. Census: Census is defined as a periodic count or enumeration of a population. Census data are necessary for accurate description of population s health status and are principal source of denominator for rates of disease & death. It provides information on: Size and composition of a population The trends anticipated in the future..age, sex and size of the population Mortality, fertility Language, ethnicity Housing 24

25 1. Census: cont The amount of data collected may vary, from as little as population size and age / sex structure on one end to a large number of: social, economic, demographic and health related variables on the other end; however, a fairly developed census mechanism would usually provide information regarding: total population, density according to per square kilometers of land area, decadal growth rate, literacy rate, economic conditions, occupational characteristics, and selected indicators of mortality like overall death rate and infant mortality rate. 25

26 1. Census: cont From these data different health indices could be calculated: Crude birth rate, crude death rate, age specific mortality rate and sex specific mortality rate are some of the examples of the indicators that could be calculated Limitation Conducting nationwide census is very expensive and it generates a large amount of data which takes a very long time to compile and analyze.. It is carried in intervals of many years (10 years). Therefore it can t assess yearly changes 26

27 1. Census: cont Sample Surveys In sample surveys, instead of covering the whole population as is done in census, only a sample, which is representative of the population, is studied and inferences about the population strength and composition are made. Sample surveys are quite relevant in underdeveloped countries where full fledged census is not possible; they are also useful in countries where census mechanism is present because they give interim information without waiting for the census which is generally done after 10 years. 27

28 In Jordan census was conducted in.. 28

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32 2. Vital statistics: Vital statistics means the ongoing recording of all vital events such as births, deaths, marriages etc. Registration of Births and Deaths is a legal requirement in our country This is a system by which all births and deaths occurring nation wide are registered, reported and compiled centrally. The main characteristics of vital statistics are: Comprehensive all births and deaths should be registered. Compulsory by law should be enforced by law. Compiled centrally so that it can serve as a source of information. Continuous it should be an ongoing process. 32

33 2. Vital statistics: cont. (a) Death Certificate : It is one of the most important source of information about the distribution of a number of diseases. 33

34 2. Vital statistics: cont. (b) Birth Certificates : These are useful for epidemiologic research as well as health services management; they provide a denominator data for calculating various important rates IMR, MMR, etc. Ideally, a birth certificate should contain information about date, place of birth, details of parents, domiciliary/ institutional birth, sex of newborn birth attendant s details, type of delivery and complications if any, age of mother and birth order of the child. (c) Other vital events : These include registration of marriages and divorces; reporting of still births; an reporting of fetal deaths. 34

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37 3. Health Service Records All health institutions report their activities to the Ministry of Health. The Ministry compiles, analyzes and publishes it in the health service directory. It is therefore the major source of health information. Advantages: Easily obtainable Available at low cost Continuous system of reporting Causes of illness and death available. 37

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39 3. Health Service Records cont Limitations: Lack of completeness health service coverage is low. Lack of representativeness a small proportion of diseased population seeks medical advice. Those patients who remained at home are not reported. Lack of denominator catchment area is not known in the majority of cases. Lack of uniformity in quality. Diagnosis varies across the level of health institutions. Lack of compliance with reporting. Irregularity and incompleteness of published compilations. 39

40 3. Health Service Records cont Notification of Infectious Diseases There are some internationally notifiable diseases. WHO member states report on Plague, Cholera, and Yellow fever. Moreover, every country has its own list of notifiable diseases. The major problems related to this source (health service records) are low compliance and delays in reporting. 40

41 4. Health Surveys What is a Survey? A Survey collects information Is a Census from all the population Is a Poll if for political information Is a Sample Survey if from just a sample of a population 41

42 4. Health Surveys cont Health surveys are studies conducted on a representative sample population to obtain more comprehensive data for monitoring the health status of a population. There are two types of health surveys: 1. Surveys of specific diseases: These are studies conducted on each specific disease. Examples are: EPI target diseases Diarrheal Diseases HIV/AIDS Tuberculosis / Leprosy 2. Surveys of general health status: These are studies on general health status of the population. They are based on interview, physical examination and laboratory tests. They are expensive. 42

43 4. Health Surveys cont Advantages of surveys based on interview: They are more representative of the health condition of the community. The denominator is known. Data are more uniform in quality. Limitations: Data accuracy is dependent on the memory and cooperation of the interviewee. Surveys are expensive. 43

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45 Information from Special Populations Information from Special Populations Some groups have well maintained and extensive health data (e.g. uniformed services, factories, mines, occupational groups, Insurance policy holders, persons covered by various health insurance programs etc Records of Hospitals and Health Services In developing countries with inadequate notifications of morbidity and mortality, hospital records are important tool for the epidemiologist as well as the health administrator. Even in countries with a well developed system of notification, hospital records are often used for epidemiological assessments and clinical research. In addition to hospitals, records from other health services (national health program offices, Community/Primary Health centers) also provide valuable data. 45

46 Other Sources of Information Depending on the information needs, the epidemiologist may need data from the: Epidemiological studies: valuable but expensive meteorological / environmental departments; from governmental offices regarding availability of medical/ paramedical manpower and available training facilities; or data of controlled drugs and their utilization may have to be obtained from the relevant Drug Controller s office. 46

47 II. Methods of data collection The main methods of collecting information are: 1. Observation 2. Interview and questionnaires 3. Documentary sources - Clinical records and other personal records, death certificates, publications etc. 47

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50 Surveillance 50

51 The word Surveillance The word "sur-veillance" means (in French) "to watch from above" ("veiller" = "to watch" and "sur" = above") (i.e. a God's-eye view looking down from on-high) The term is often used for all forms of observation, not just visual observation. 51

52 Definition of Surveillance Public health surveillance (sometimes called epidemiological surveillance) is : the ongoing systematic collection, analysis, and interpretation of outcome-specific data essential to the planning, implementation, and evaluation of public health practice, closely integrated with timely dissemination of these data to those who need to know. Outcomes may include diseases, injury, and disability, as well as risk factors, vector exposures, environmental hazards, or other exposures. The final link of surveillance chain is the application of these data to prevent and control human diseases and injury. 52

53 Surveillance Principle Surveillance is: Information for Action If you don't use it, then do not ask for it! However: Good surveillance does not necessarily ensure the making of the right decisions, but it reduces the chances of the wrong ones A. D. Langmuir (1963) 53

54 History In 1950, the term surveillance was restricted to public health practice to watching contacts of serious communicable diseases To early detect symptoms To institute prompt treatment Example: Smallpox 54

55 Surveillance, surveys, registries and HMIS: Surveillance is systematic ongoing collection, collation, and analysis of data, and the timely dissemination of information to those who need to know so that action can be taken A survey is a one data collection episode Registries are not for immediate action Health Management Information Systems (HMIS) for annual reports 55

56 Note the Differences: Registers are archival health information Surveillance is dynamic as compared with surveys: Interplay between epidemiologic studies and control activities Surveillance is not mere: Reporting Monitoring Data collection 56

57 Continuous versus Periodic Data Collection Continuous Data Collection Periodic Collection Data Collection Small team Large team or multiple teams Data accessibility Initially slow Faster turnaround Data usefulness for trend analysis Ongoing results Results only after three rounds of data collection Evaluation of health intervention Continuous monitoring of impact Timing of collection often not linked to intervention Budget Line item in health budget One-off investment at each cycle 57

58 Goals and Uses of Surveillance Detect outbreaks or epidemics Detect changes in trends over time, portray natural history of diseases Evaluate control measures Estimate magnitude of morbidity and mortality Ensure equity in health care (mortality and morbidity) Facilitate planning Making projections, understanding burden of disease and justifying allocation and or redirection of resources Stimulate epidemiologic research Generate/ Test hypotheses (e.g. changes in health practice) Identify risk factors (in-depth studies) 58

59 Uses of Public Health Surveillance Estimate magnitude of the problem Portray the natural history of a disease Determine distribution and spread of illness Detect outbreaks Generate hypotheses, stimulate research Evaluate control and prevention measures Monitor changes in infectious agents Detect changes in health practices Facilitate planning 59

60 Objectives of Surveillance Early detection and prediction of outbreaks Description of the magnitude of disease Understanding risk factors for diseases Monitoring trends of endemic disease Monitor programme performance and progress towards a control objective Estimate future disease impact 60

61 Added values of Surveillance High-quality surveillance increases credibility of public health care providers: Encourages transparency Reduces over-reaction Attract donors Encourages implementation of new interventions; new conjugate meningococcal vaccines Facilitates better management of disease control and other public health programs SAVES LIVES!!!! 61

62 Health Care System Importance of Good Reporting Public Health Authority Event Reporting Data Intervention Feedback Information 62

63 1 Delayed Detection Means Delayed Response First Case Late Detection Delayed Response CASES Opportunity for control DAY 63

64 Early Detection Early warning indicators: Count of cases (?) Attack rates (stratified) Case-fatality rates Temporal component Defined thresholds Notification of cases Suspect and probable Case-based data Immediate or weekly CASES First Case Early Detection First Case Late Detection Rapid Response DAY Delayed Response Opportunity for control Potential Cases Prevented DAY 64

65 Types of Surveillance Surveillance may be based on many different data sources can be classified in a number of ways, including: i) the means by which data are collected (active versus passive surveillance ); 65

66 Active vs. Passive Surveillance Active Surveillance: Health department solicits reports Passive Surveillance: Reports are initiated by source for data 66

67 Surveillance of Disease vs. Persons Surveillance of Disease: The continuing scrutiny of all aspects of occurrence and spread of disease that are pertinent to its effective control Surveillance of Persons: The continuing scrutiny of disease contacts, high risk groups in order to promote prompt recognition of infection or illness 67

68 Levels of Surveillance National: Periphery: (e.g., PHCC catchment area, city) Intermediate: Provincial Central International: International Health Regulations

69 Special Surveillance Programs Natural and man-made disasters (emergencies) During Special events of mass gatherings الحج (Pilgrims to Makkah Olympics Laboratory-based surveillance: Emerging pathogens Antimicrobial resistance Infection control Behavioural risk factors Others 69

70 Systems of Disease Surveillance Notifiable disease reporting systems Laboratory-based surveillance Hospital-based surveillance Population-based surveillance Vital records (birth and death certificates) Registries 70

71 Routine and sentinel surveillance Sentinel surveillance; The surveillance of a specified health event in only sample of the population at risk using a sample of possible reporting sites. The sample should be representative of the total population at risk. Passive surveillance; Routine surveillance where reports are awaited and no attempt make actively seek reports from the participants in the system. 71

72 Sentinel Surveillance Often provides an early alert for outbreaks Most useful for diseases that occur frequently Not intended to capture all cases Focal points: Clinics, hospitals or laboratories Strategic locations Representative to population (socio-demographic) High risk groups Less sites but better quality of data bring attention to problems in practices, procedures or systems Useful for research activities 72

73 Reporting Channels WHO / HQ WHO/ EMRO National Communicable Diseases Surveillance District / Region PHC PHC PHC PHC PHC 73

74 Reportable Diseases Vary from one country to another Differences within countries Changes over time Adding one single disease to the list could cost a lot: Money, time, avoidable confusion Variables collected should be indicators of potential or arising problems rather than identifying risk factors Report only confirmed cases? 74

75 Frequency of Reporting Diseases Weekly? Appropriate most times Monthly? Less sensitive Quarterly? At national level Daily? Daily reporting could be cumbersome Daily reporting may be required during emergencies, disasters Avoid inconsistencies in case definitions Reporting suspected vs. confirmed cases 75

76 Data Collection Forms Should be (for line-listing): Simple Minimum content Layout easy to understand Easy to reproduce Special data collection forms: Special surveillance programs (e.g., Malaria, vector control) During outbreaks (Locally acquired or imported?) Eradication activities 76

77 Public Health Laboratories Fully linked to epidemiological surveillance Ability to confirm diagnosis of epidemic prone diseases of national interest Monitor and report selected pathogens Meningococcal meningitis and other bacterial meningitis Cholera, Shigellosis and salmonellosis Viral Hemorrhagic fevers, etc Monitor antimicrobial resistance 77

78 Analysis of Surveillance Data 78

79 Key Indicators Absolute numbers Proportions Rates Percentages Threshold 79

80 80 Information Management

81 Evaluation of Surveillance Systems 81

82 Goals of Evaluation of Surveillance To improve existing surveillance systems To modify systems because of changes in Priorities Epidemiology Diagnostics To optimize the use of available resources 82

83 International Health Regulations 2005 Current: Notification to WHO of a case of cholera, plague or yellow fever... IHR 2005 Public health emergencies of international importance Obligation to establish core capacities Assistance to States Context specific & flexible recommended measures External advice (emergency and review committees) regarding IHR 83

84 Information Loop of Public Health Surveillance Public Reports Summaries, Interpretations, Recommendations Health Care Providers Health Agencies Analysis 84

85 National Notifiable Disease Surveillance Reporting mandated by state law/regulation Health care providers, laboratories report to local HD (county) County HD submits reports to State Reports transmitted to CDC primarily through National Electronic Telecommunications System for Surveillance (NETSS) 85

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87 DEFINITIONS Disease notification is a process of reporting the occurrence of disease or other healthrelated conditions to appropriate and designated authorities. A notifiable disease is any disease that is required by law to be reported to government authorities. 87

88 DEFINITIONS A notifiable disease is one for which regular, frequent, and timely information regarding individual cases is considered necessary for the prevention and control of the disease. Physicians are required by law to report cases of certain infectious diseases. Unfortunately, many do not. 88

89 REASONS FOR SURVEILLANCE Evaluate the effectiveness of control and preventative health measures Monitor changes in infectious agents e.g. trends in development of antimicrobial resistance Support health planning and the allocation of appropriate resources within the healthcare system. Identify high risk populations or areas to target interventions Provide a valuable archive of disease activity for future reference. 89

90 Notification: when and how IDSR form 001: For immediate/case based reporting of diseases. Immediate reporting allows for timely action to be taken to prevent the re-emergence or rapid transmission of epidemic prone diseases or events, especially diseases due to highly pathogenic and lethal infectious. 90

91 Notification: when and how Make the initial report by the fastest means possible (telephone, text message, facsimile, e- mail, radiophone)... Follow up the initial verbal report with a written report of the case-based report form. IDSR 001A when the case is suspected and IDSR 001B when there is laboratory confirmation. Below is a list of diseases/events requiring immediate reporting. 91

92 Diseases/Events reported with form IDSR 001 Acute Flaccid Paralysis (AFP) Acute hemorrhagic fever syndrome (Ebola, Marburg, Lassa Fever, RVF, Crimean-Congo) Adverse event following immunization (AEFI) Anthrax Chikungunya Cholera Cluster of SARI Diarrhoea with blood (Shigella) Dracunculiasis Influenza due to new subtype Maternal death Measles Meningococcal meningitis Neonatal tetanus Plague Rabies (confirmed cases) SARS Smallpox Typhoid fever Yellow fever Any public health event of international concern (infectious, zoonotic, food borne, chemical, radio nuclear or due to an unknown condition) 92

93 Notification: when and how IDSR form 002: For weekly reporting of new cases of epidemic/pandemic prone diseases. IDSR form 003: For routine monthly notification of other diseases of public health importance. 93

94 Diseases that require monthly reporting Acute viral hepatitis AIDS (New Cases) Buruli ulcer Diabetes mellitus Diarrhoea with severe dehydration in children under 5 years of age HIV (new detections) Hypertension Influenza-like illness Injuries (Road Traffic Accidents) Leprosy (quarterly) Lymphatic Filariasis Malaria Malnutrition in children under 5 years Mental health (Epilepsy) Noma Onchocerciasis Severe pneumonia in children under 5years of age Sexually transmitted diseases (STIs) Trachoma Trypanosomiasis Tuberculosis (quarterly) Underweight Newborns (less than 2500 g) 94

95 CHAIN OF REPORTING HCP DNO LG MOH WHO/CDC FMOH SMOH Key: HCP: Health care providers DNO: Disease notification officer LG MOH: Local Government Medical Officer of Health SMOH: State Ministry of Health FMOH: Federal Ministry of Health 95

96 Surveillance Team Needs to Work Together Tabloids Newsp apers Lack of coordination in outbreak team Scientific press TV/Radio 96 WHO/EMC

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