Surveillance Dr Amna Rehana Sidiqui Assistant Professor Department of Family and Community Medicine

Learning Objectives: After studying this lesson you will be able to: Define public health surveillance and its main components List the elements and uses of surveillance Describe sources for data that can be used for public health surveillance Describe the flow of information for reportable diseases

Public Health Surveillance “ Ongoing systematic collection, analysis, and interpretation of outcome-specific data for use in the planning, implementation, and evaluation of public health practice.” Definition by Centers for Disease Control (CDC) USA

Surveillance is Information for Action

Reported TB Cases* United States, 1982–2006 Year No. of Cases *Updated as of April 6, 2007.

The components of surveillance and resulting public health action

Elements of surveillance system Cases and deaths due to a given disease. Laboratory results. Prevention and control measures. Environment. Vector. Reservoir. Population

Fig. 2Cholera: Reported cases & Case fatality Rates (CFR), by Continent CFR= # of TB cases dying in that yr / # of TB cases identified in that yr By

Conceptual Taxonomy Public Health Surveillance Disease Traditional‘Syndromic’ DrugVaccine Birth defectInjuries Other Etc. Infectious Disease Medical Utilization and Adverse Events Other Products/Services

Purposes of Public Health Surveillance Assess public health status about a factor/s Setting public health priorities; e.g. polio first… Evaluate prevention and control programs Generating hypothesis & Stimulating research; e.g. relationship of TB and HIV

Uses of Public Health Surveillance Estimate magnitude of the problem Guide immediate action for cases Determine geographic distribution of illness Portray the natural history of a disease Detect epidemics/define a problem Generate hypotheses, stimulate research Monitor changes in infectious agents Detect changes in health practices Facilitate planning Evaluate control measures Policy Changes e.g. Measles vaccine booster

TB Case Rates,* United States, 2006 < 3.5 (year 2000 target) 3.6–4.6 > 4.6 (national average) D.C. *Cases per 100,000.

Year Reported Cases (Thousands) Vaccine licensed MEASLES — by year, United States, 1983– Year Reported Cases T housands) Evaluate control measures of MEASLES United States,

Data Sources for Surveillance Notifiable diseases (Reporting is mandatory, legal, & reportable diseases vary by region) Laboratory specimens (Salmonella—serotypes, Blood Lead Measurements, HIV) Vital records (Infant Mortality Surveillance, Birth & Death Certificates) Sentinel surveillance (selected sites ; work-related Asthma, lead poisoning,…) Registries (Cancer& congenital defects) Surveys (Nutrition Examination Survey,….) Other data sources (Vaccine Adverse Event Reporting, drug reaction,…)

15 Types of Surveillance Passive surveillance health-care providers send reports to a health department on the basis of a known set of rules and regulations, is called passive surveillance. Inexpensive, provider-initiated Good for monitoring large numbers of typical health events Under-reporting is a problem Active surveillance ▫active surveillance (health department- initiated) health department approach health providers ; is usually limited to specific diseases over a limited period of time, such as after a community exposure or during an outbreak.

Attributes of a surveillance system --- Simplicity – time spent in maintaining --- Flexibility – can adapt to changes --- Data quality - validity --- Acceptability – by stakeholders --- Sensitivity-can detect … --- Representativeness --- Timeliness – detected and reported --- Stability - continues without breaks

Data collection 1. Routine reporting system Hospitals, health centers, health facilities, CHW. Advantages: Inexpensive and efficient. Standardized., Disadvantages: Incomplete Busy doctors & nurses

New and complex disease entities must also be monitored… New syndromes may emerge that present in an atypical manner Syndromic surveillance uses health-related data that precede diagnosis and signal a sufficient probability of a case or an outbreak to warrant further public health response

Day 1- feels fine Day 2- headaches, fever - buys Tylenol Day 3- develops cough - calls nurse hotline Day 4- Sees private doctor – dx with “flu” Day 5- Worsens - calls ambulance seen in ED Day 6- Admitted - “pneumonia” Day 7- Critically ill - ICU Day 8- Expires - “respiratory failure” Case enters surveillance system through hospital reporting Example of Passive Surveillance

Day 1- feels fine Day 2- headaches, fever - buys Tylenol Day 3- develops cough - calls nurse hotline Day 4- Sees private doctor - dx “flu” Day 5- Worsens - calls ambulance - seen in ED Day 6- Admitted - “pneumonia” Day 7- Critically ill - ICU Day 8- Expires - “respiratory failure” Case is under immediate investigation by the LHD because of the pre-diagnostic information gathered Pharmaceutical Sales Nurse’s Hotline Managed Care Org Ambulance Dispatch (EMS) ED Logs Absenteeism records Example of Syndromic Surveillance

2-Sentinel reporting system Selected health units; e.g. influenza in USA to develop vaccine for that year after typing for circulating strain for that year Advantages: More consistent pictures. Motivated. Disadvantages: Not representative Changes with served population e.g. use of the same influenza vaccine in other countries which was identified for USA population

3-Surveys and special studies e.g. The National Health and Nutrition Examination Survey (NHANES) program of studies designed to assess the health and nutritional status of adults and children in the United States. Advantages Broad estimate. Measure reliability. Relieve health care workers. Disadvantages: Large sample size. Expensive

4-Case and outbreak investigations e.g. HIV cases when first identified On occasion. Used as a next step to plan intervention Used as a next step e.g. to plan intervention Post outbreak surveillance (e.g. to confirm that outbreak is over) Early warning systems: e.g. surveillance for risk factors in malnourished children who may be vulnerable and will acquire diseases before it spreads in healthy children

Data collection procedures Operational definition Instruments Registers Questionnaires Case investigation form Pre-test the instrument Source; Laboratory; hospitals…

Data collection Training Supervision Quality control Reporting; frequency for monitoring and interpretation

Analyze and interpret data Summary tables. Disease charts. Maps. Rates & ratios More analysis for pattern and causes

Steps in Surveillance data Analysis Data quality Descriptive analysis ▫Time ▫Place ▫Persons Generate hypothesis Test hypothesis

Data Quality Issues Missing values Attraction to round figures Data entry errors Bias related to lack of representativity ▫Cases more severe ▫Urban > rural ▫Source not represented (private sector, GPs)

Data Quality completeness and validity of the data percentage of "unknown" or "blank Case definition Training of team Manuals Active versus passive

Burden of diseases Reporting only confirmed cases may not reflect true status resulting in ineffective control as an iceberg situation may exist with clinical and subclinical cases Only severe cases are reported Under reporting may lead to high case fatality rates; resource utilization affected

Timeliness of disease notification 1.Health event occurs 2.Identified by health care system 3.Reported to local health authority 4.Verification/investigation by PHS 5.Health event reported to other systems 6.Analyses of health data 7.Dissemination of surveillance finding 8.Actions based on surveillance findings

Early warning system Major threats to the population; 0-4 & 5 or more years of age, have been identified. Severe malnutrition, injuries, acute watery diarrhoea, bloody diarrhoea, acute flaccid paralysis, acute respiratory infections, neonatal tetanus, malaria, suspected measles, suspected meningitis, acute jaundice syndrome and acute FUO A threshold for each is defined; unusual pattern or occurrence will triggers investigations and responses.

8/5/1430Dr. Salwa Tayel 33 Prepare and present reports Review objectives. Review tables, graphs & maps. Add short narrative to explain findings COMPARING TO PREVIOUS REPORTS. Describe action plan. Disseminate the report

8/5/1430Dr. Salwa Tayel 34

Surveillance system in Hospital High risk of hospital acquired infections (HAI) that leads to high mortality, longer length of stay, and huge costs of hospitalization First Surveillance and then research How much mortality, cost, length of stay could be averted by reducing HAI? How will you start? Person, place and time ? EXERCISE

Needs and Steps Assess your resources Step wise fashion or all at once? Training of individuals Pilot testing Obtaining data, case definitions, standards Monitoring/continuous / frequency ? 3 months Interpretation ; comparing rates by quarters Analyses ; developing research hypothesis Dissemination ; publication

Descriptive epidemiology What are the infection rates in …. What is the mortality rate in …. What is the usual length of stay … What are the important organisms that are reported from ….. Any previous data? Any previous outbreak data? Numerator? Denominator? Setting/s defined

Numerators Case definitions required Sepsis, Pneumonias, UTI, SWI etc. Who will diagnose ? (for stability of rates) Standard definitions / CDC Laboratory based surveillance Active surveillance

Hospital Acquired Infections in High Risk Area (Mixed type ICU) April 1998 – March Rate / 1000 Device DAys BSI Pneumonia UTI Apr- Jun'98 Jy- Sep'9 8 Oct- Dec'9 8 Jan- Mar'9 9 Apr- Jun'99 Jul- Sep'9 9 Oct- Dec'9 9 Jan- Mar'0 0 Apr- Jn00 Jy- Sep'0 0 Jan- M01 Reference 50 th Percentile BSI=Blood Stream Infections; UTI=Urinary Tract Infections

40 Summary Surveillance for ……… ▫Case definition ▫Sources of data ▫Analysis ▫Interpretation ▫Dissemination - REPORTING Actions