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Introduction To and Overview Of Introduction To and Overview Of Case Based SurveillanceCase Based SurveillanceNASTAD Global Program
Overview
Discussion About:
– Epidemiological Surveillance
– Case-based Surveillance Reasoning, benefit and added value Requirements for system implementation
– How Implementation Might Look Case-based surveillance Biological and behavioural surveillance
Epidemiological Surveillance
Surveillance
What is Surveillance?– Keeping a close watch over something
What is Epidemiological Surveillance?– The ongoing, systematic collection, analysis, and
interpretation of health data essential to planning, implementing, and evaluating public health practice, closely integrated with the timely dissemination of these data to those who need to know
Why Do Epidemiological Surveillance?
To understand the disease in order to:– To prevent the disease – To protect the public’s health and wellness
To promote public health and a public health response by identifying:– Public health problems– Populations who are affected– Risk factors
Surveillance is essential for planning, implementation, and evaluation of public health practice
Methods Used for Epidemiological Surveillance
Population-based Surveys– A sample of a population is defined, sampled, and
surveyed– With modeling, findings may be generalizable
Sentinel Site Surveillance– As above, but sampling occurs only at a set number of
locations – Finding may be generalizable to some part of the
population
Case-based Surveillance– A ‘census’ of all known/diagnosed cases of a disease
Methods of Surveillance: Population-based
Demographic and Health Survey National representative household survey
– Population, Health, Nutrition Sample size:
– 5,000 to 30,000 households Regular frequency:
– +/- 5 years, to allow comparisons over time Random and representative sample of households selected
– Household: All who normally sleep there (including staff), and guests who spent the previous night
60 minutes survey with all eligible:– Men age 15-59; Women age 15-49 ; Info about children ages 0-5
Data available via www.DHS.org
Types of Surveillance: Sentinel Surveillance
Sentinel (and Behavioral) Surveillance– Specific sites and population groups– Predetermined number of persons – Testing done in regular and consistent way (WHO)
Communicable diseases Antenatal Men who have sex with men Injection drug users Commercial sex workers Truck drivers
Data available via MoH’s, www.FHI.org, www.DHS.org, or other
Types of Surveillance: Case-based
Case-based Surveillance– Regular and systematic reporting of all cases – Stronger system if data come from many sources– A living system that is updated as cases are reported– Sensitive to outbreaks, changes in trends
Discussion
What methods of surveillance are in use in your country?
What are some pros and cons of each method of surveillance?
Do you see the data being used to guide:– Planning, implementation, evaluation?– Are data disseminated in a timely and routine
fashion?
Why Case-Based Surveillance?
Evolution of Data Needs
Need or desire for—or possible access to—epidemiologic data in countries has evolved over the past 10 years
PEPFAR I (2004): Few national level HIV care and treatment programs– Surveillance need at that time was to monitor HIV (or AIDS) in
general population to understand what was happening.
PEPFAR II (2009): Many national large scale prevention, care and treatment programs– People are living with HIV for many years; planners need
epidemiologic information about people who are diagnosed with HIV to know how to best treat and best prevent HIV.
Today: There are usable data are everywhere– Program-driven M&E and patient tracking required this.
Benefits of HIV/AIDS Case Surveillance
Provides an ongoing and comprehensive understanding of a country’s epidemic– Who– Where– When– How
Allows for better allocation of resources– Prevention– Care and Treatment
Provides context for M&E information
Leverages existing information; ‘low’ resource needs
Why Case-Based Surveillance
Basic Elements of Case-Based Surveillance
As Easy As…
HIV/AIDS Case Surveillance System: Basic Elements
A.Define what you want to know
– What do you want to be able to describe about HIV/AIDS?
– What do you want to be able to describe about trends over time?
– What do you want to be able to describe about the population?
HIV/AIDS Case Surveillance System: Basic Elements
B.Define what needs to be reported to answer your questions
– HIV infection (all stages)or
– Advanced stage HIV disease (stages 3, 4)or
– AIDS (stage 4)
Monitor HIV Disease
HIV disease sentinel events
HIV exposure(exposed infants or
sexual transmission)
HIV infection 1st positive
HIV test1st CD4 count 1st CD4
count <350
1st viral load 1st CD4
<200AIDS-related Opportunistic
Infection Death
Monitor HIV Disease
HIV disease sentinel events
HIV exposure(exposed infants or
sexual transmission)
HIV infection 1st positive
HIV test1st CD4 count 1st CD4
count <350
1st viral load 1st CD4
<200AIDS-related Opportunistic
Infection Death
AIDS Case Reporting
Monitor HIV Disease
HIV disease sentinel events
HIV exposure(exposed infants or
sexual transmission)
HIV infection 1st positive
HIV test1st CD4 count 1st CD4
count <350
1st viral load 1st CD4
<200AIDS-related Opportunistic
Infection Death
HIV Case Reporting
HIV/AIDS Case Surveillance System: Basic Elements
C. Define which other events should be reported to help you answer what you want to know– 1st positive test
First event for a person… sets the clock
– 1st CD4+ test How long post diagnosis are CD4 tests done? Do counts seem to be high or low?
– 1st CD4+ < 200 What is the average time from HIV diagnosis to AIDS diagnosis? How many people who are eligible for ART are on ART?
– HIV exposure (children) What happens to the babies exposed to HIV?
– Death What is the average time from HIV diagnosis to death?
HIV/AIDS Case Surveillance System: Basic Elements
D. Define who must report– Public health facilities– Laboratories– Private health facilities– Other
HIV/AIDS Case Surveillance System: Basic Elements
E. Define how cases will be linked and cleaned
– Name-based John Adams Jane Allen
– Code-based JA1268F JA1268F
F. Define how cases will be reported– Paper– Electronic– Where will cases be cleaned and de-duplicated– Where will cases be stored
Discussion
In your country:
A.Is there a need for this?
B.Do you think there is/could be interest in this?
Discussion
C. In your country, are there:
– Local data collection systems?
– Larger tracking or M&E systems?
Patient Registers
Patient Registers
Patient Care Record
EMR
Discussion
D. Are there any existing data pathways that could be used?
Discussion
What are some questions that can be answered via case-based surveillance? And the Public Health benefit
– Do people test for HIV early or late in their infection? Implications for increased HIV transmission and years lost of life; would look to have more
‘early testers’.
– What is the average time between HIV diagnosis and AIDS diagnosis and/or death? As above. Would look to increase the time between events.
– What proportion of people who test positive for HIV enter into the treatment and care system? How can the referral system be improved to capture all?
– What proportion of people in the treatment and care system access regular and routine care? Are national standards adhered to? Are other resources needed to support routine care?
– What proportion of those eligible for ART have access? Are the national standards adhered to? What can improve access?
Some Important Considerations
The Need for a Unique Case Identifier
Patient Identification
– What it is A unique way to identify each case (person)
– Why it is important Patient identification is important if we want to have a unique
count of persons infected with HIV Patient identification allows patient tracking over time Each event is entered into the system to determine if it is a
unique (new) record. Some will be new cases; some will be an update to an existing patient in the system. Updates include:– Transition from HIV to AIDS– A pregnancy– A visit to a different clinic system– A death
Selecting a Unique Case Identifier
The case identifier must:– Be unique to the individual – Not change over time or allow time of change to be known – Be easy to identify from a clinical record– Be something that is or is derived from routinely collected data
The case identifier must be able to:– Distinguish duplicate reports for the same person– Distinguish cases with the identifier who are different persons– Allow follow-up information from the surveillance program and
healthcare provider to be easily connected with existing information
Discussion
In your country, is there something like a unique ID code in use?
Data Management and Cleaning
Data Deduplication– What it is
An evaluation and assessment of each case entered into the system to determine if it is a unique (new) case, or if it is an update on an existing patient in the system
– Why it is important Deduplication is important if we want to have a unique
count of persons infected with HIV Deduplication, and matching records to the source file,
allows patient tracking over time
Data Management and Cleaning
Data Deduplication– How it can be done
Manually or automatically Cases are matched by certain selected criteria:
– Unique ID Code - Each record needs one for each patient Ideally, people have national identifiers (and they are
used!) before a record is entered More often a unique identifier must be established from
some combination of common demographic information The more unique, the more certainty that records are for
the same person– Combination of other variables that are somewhat unique:
Name Parents Names Date of Birth Location of Birth Location of Residence
Records that match are appended to each other to track over time
Data Management and Cleaning
Data Validation– What it is
A review of data to see that what is submitted is accurate Examples:
– Are the report dates more recent than the last data transfer?
– Does everyone have a birthdate?– How many fields are completely empty?
– Why it is important Speaks to the quality of the data People make mistakes. The wrong file can be uploaded, data
can be deleted, or records can be shifted.– How it can be done
Chart review (sub-set) vs. submitted data Record review (sub-set) vs. submitted data
A Central Management System
Why? De-duplication of cases between and among systems to provide a unique count of cases
– Patient tracking within and between networks– Better trend monitoring– Additional data source to triangulate with existing
prevalence estimates and/or program outputs
Greater controls for patient privacy and data confidentiality
Ownership of surveillance data buy government to enable leadership in public health functions
Discussion
In your country, is data management and data validation visible or available?
Putting the Pieces Together
~ an example from Haiti
Strategic Planning
1. What is the goal?– Stop mother to child transmission
2. What is needed to reach the goal?– Test all pregnant women– Provide treatment, care, outreach, support– Provide follow-up after birth for exposed children
3. What resources and systems exist?– Patient registers– Some reporting pathways– Case managers
Sample:Reporting the Spectrum of HIV/AIDS
Morbidity and Mortality
Pregnancy+HIV+ Test
Pre-NatalPre-Natal and and PediatricPediatric Surveillance Surveillance
Prophylaxis at Delivery
1st ART (PMTCT Prophylaxis)
Entry to PMTCT
Prophylaxis Post-Delivery
+ while Nursing
Infant Visit within 72 Hours
Infant PCR
Infant HIV Screen (6 months)
Infant HIV Screen (18 months)Entry to ART/Care
Entry to Care (if HIV+)
Infant Prophylaxis after birth
(AZT, NVP)
MESIMonitoring, Evaluation,
and Surveillance Interface
NationalEMR
(I-TECH)
Local EMRs
VCTPMTCT
PEPFARTreatment and
Care
GHESKIO/PIHTreatment and Care
HIV/AIDS Case Surveillance
Centralized Database
Epidemiologic Analyses
Periodic Reports
Quality Assurance
Laboratory-Based
Reporting
(MESI, Haiti, Daily/Weekly)-“Surveillance”-Online
(MESI, Haiti, Daily/Weekly)-“Surveillance”-Offline
(I-TECH, WA, Biweekly/Monthly)-EMR
(GHESKIO, Haiti, Biweekly/Monthly)-EMR
(PIH, MA, Biweekly/Monthly)-EMR
HAITIHIV SURV
MOH
MESI
ITECHMESI 1
De-duplication
Surveillance Loop
Sample Roles and Responsibilities
Sample Data Collection Tool
Proposed:PMTCT Case ‘Flagged’ by case surveillance systemSite level staff contacted to arrange for follow-up Sentinel event tool used to track woman pre- and post-natallyCues for staff follow-up:
– Tool
– User interface
– National data system
Summary
Case Based Surveillance
When devising or expanding a case-based surveillance system, priorities include:– Knowing what you want to know
and– Tracking what you want to track
However, you might also consider:– Best use of existing resources
where resources include:– Data systems, data variables, data flow, and data-
personnel