Seminar on Rapid Epidemiological Assessment, Department of Community Medicine

1. RAPID EPIDEMIOLOGICAL
ASSESSMENT
PRESENTERS: Isaac Lalrawngbawla
Sandra Fernandez
MODERATOR: Prof. Shantibala K
17th January 2024

2. OUTLINE OF
PRESENTATION
• Introduction
• Quantitative methods
• Qualitative methods
• Geographic Information System
• CASPER
• Benefits
• Recommendation
• References

3. Introduction
• Health managers need timely and accurate information
• Many traditional methods not well suited to limited
financial resources and with few skilled people
• Rapid assessment refers to a broad collection of
epidemiological, statistical and anthropological
techniques which aim to provide accurate information
quickly, at a low cost, in a simple format

4. Developme
nt of REA
Research
1981, ACHBRD
• REA began as an amalgam of
concepts and techniques
• Largely inspired by the
'quick and dirty' methods
• Sought to develop REA for
use health programmes
• REA as one of six areas
for funding of research in
developing countries

5. Quantitative methods

6. WHO-EPI Cluster sampling

7. History
• 1968,1969: WHO conducted surveys
in Niger, Nigeria & Togo to
ascertain smallpox vaccination
• 1982: experience was adapted for
infant immunization coverage
-became the EPI 30x7 Cluster
Survey
• Since then, EPI cluster survey

8. • Cluster sampling technique
-30 clusters, 7 children
• Plan based on NIS
• Select age group
• Decide source of information
• No. of interviewers, length of survey
• Identify clusters

9. • Cluster sampling technique
• 30 clusters, 7 children
• Plan based on NIS
• Select age group
• Decide source of information
• No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household
• Determine how to define ‘fully
immunized’
• Depend upon immunization
schedule
• Variations within the country

10. • 30 clusters, 7 children
• Plan based on NIS
• Select age group
• Decide source of information
• No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household
• Children aged 12-23 months
• Children aged 18-29 months
• Children aged 0-11 months

11. • Plan based on NIS
• Select age group
• Decide source of information
• No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household
Card and/or History

12. • Select age group
• Decide source of information
• No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household
•
𝑛𝑜. 𝑜𝑓 𝑖𝑛𝑡𝑒𝑟𝑣𝑖𝑒𝑤𝑒𝑟𝑠 𝑎𝑣𝑎𝑖𝑙𝑎𝑏𝑙𝑒
2
= 𝑛𝑜. 𝑜𝑓 𝑡𝑒𝑎𝑚𝑠
•
30
𝑛𝑜. 𝑜𝑓 𝑡𝑒𝑎𝑚𝑠
= 𝑛𝑜. 𝑜𝑓 𝑑𝑎𝑦𝑠 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑

13. • Decide source of information
• No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household
• Cumulative list of community sizes
• Sampling interval
• Random number (≤sampling interval)  1st community
• Add sampling interval to random number  subsequent c

14. 12765
39431
66097
92763
119429
146095
172761
199427
Sampling interval =
800000/30=26666
Random number: 12765
1
2

15. 12765
39431
66097
92763
119429
146095
172761
199427
Sampling interval =
800000/30=26666
Random number: 12765
3
4

16. • No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household

17. • No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household
Rural areas (HH list available)
• Obtain list
• Number HHs on list
• Select random number  first HH to

18. • No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household
Rural areas (HH list not available)
• Select central location
• Randomly select direction
• Walk in selected direction, count HH
• Select random number (n)
• Return to start, select nth HH from ce

19. • No. of interviewers, length of survey
• Identify clusters
• Select starting household
• Select subsequent household
Urban areas
• If subdivisions exists, number them
Select random number (n), nth HH = ini
HH list: exist or not
• If subdivisions not exist
Divide into subunits of approx. equal

20. • Identify clusters
• Select starting household
• Select subsequent household
Single family dwellings
• One nearest to first
Front door closest

21. • Identify clusters
• Select starting household
• Select subsequent household
Single family dwellings
• One nearest to first
Front door closest

22. • Identify clusters
• Select starting household
• Select subsequent household
Multi-family dwellings
• Choose one floor at random
• Number the HHs on the selected floor
• Randomly select one HH  2nd HH: nearest doo
• Randomly choose direction (↑ or ↓), visit ne
• Next, nearest door of nearest building

23. • Identify clusters
• Select starting household
• Select subsequent household
Hilly terrain, scattered dwelling
• If not possible to map area, rely on loca

24. Lot Quality Assurance Samp

25. • Originated in the
manufacturing
industry for quality
control purposes
• Rather than checking
each item, check
sample of lots to
accept or reject
entire lot

26. • Monitor the quality of
services
• Lots may be villages
and communities,
catchment areas of
hospitals or health
centers
• Identify health

27. Advantages
• Allows managers to
direct supervision &
other resources to
the units that need
it most
• Interpret data as
soon as they are
collected from a
Disadvantage
• Selecting a lot
sample size and a
decision value,
involves the
assessment of risks

28. Steps for
conducting LQAS

29. Depending on what you want to study
Identify target population
Set assessment criteria
Step 1: Set a level of accuracy
• LQ technique gives you a choice of
accuracy levels from +1% to +10%

30. Step 2: Set a level of confidence
• In studies using the LQ technique,
you may choose one of three
levels,90%, 95% and 99%
• 95% is recommended for most studies

31. Step 3: Make first estimate of total
sample size

32. Step 4: Estimate the size of the target
population
• If reliable numbers are available from
local vital statistics or birth
registries, use them
• If not, you can base a calculation on
estimates of the total population size

33. Step 5: Calculate sampling fraction
• Sampling fraction shows what proportion
of a total population will be included in
a study
𝑆𝑎𝑚𝑝𝑙𝑖𝑛𝑔 𝑓𝑟𝑎𝑐𝑡𝑖𝑜𝑛 (%) =
𝑡𝑜𝑡𝑎𝑙 𝑠𝑎𝑚𝑝𝑙𝑒 𝑠𝑖𝑧𝑒
𝑡𝑎𝑟𝑔𝑒𝑡 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛
× 100
• If sampling fraction >10%, recalculate
total sample size
𝑡𝑜𝑡𝑎𝑙 𝑠𝑎𝑚𝑝𝑙𝑒 𝑠𝑖𝑧𝑒

34. Step 6: Count number of lots
• Health center catchment areas
• Supervisory areas

35. Step 7: Calculate minimum lot
sample size
𝑀𝑖𝑛𝑖𝑚𝑢𝑚 𝑙𝑜𝑡 𝑠𝑎𝑚𝑝𝑙𝑒 𝑠𝑖𝑧𝑒 =
𝑡𝑜𝑡𝑎𝑙 𝑠𝑎𝑚𝑝𝑙𝑒 𝑠𝑖𝑧𝑒
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑙𝑜𝑡𝑠

36. Step 8: Set threshold levels
• Two threshold levels for LQ studies
o Minimum level of acceptable
o Upper level of desirable

37. Step 9: Select decision value
• Highest number of individuals in a
lot that you can find to be not
receiving a service and yet still
classify the lot as acceptable
• Once you reach decision value, you
judge the lot unacceptable

39. Illustration of terms
• Area
• Lot
• Sample
• Sampling point
• Sampling point area

40. e between EPI cluster sampling & LQAS
Issue 30/7 cluster sampling LQAS
Sub-
populatio
ns
Called cluster,
usually based on
geographical and
political boundaries
Called lots, usually
based on
geographic and
political, boundaries
Sample
size
210 Dependent on the
desired proportion
and level of risks
List of
units
No need for list of
units
Need list of all
units
Outcomes Overall estimates, Overall estimates,

41. e between EPI cluster sampling & LQAS
Issue 30/7 cluster sampling LQAS
Precision Set to be within ±10
percentage points of
the population value
Can be set at
different level
Cost Decrease travel and
preparation time
Needs to sample each
lot, yielding higher
cost
Reasons
for
potential
bias
Heterogeneous
cluster, the
households are not
randomly selected,
Small samples in each
lot

42. e between EPI cluster sampling & LQAS
Issue 30/7 cluster sampling LQAS
When to
use
Interest in an
overall population
estimate obtained at
a low cost
Interested in
information from each
lot, and a
traditional
stratified sample not
affordable

43. Case-control methodology

44. • Case-control studies starts with the
identification of
-persons with outcome of interest and
-suitable control group of persons without
outcome
Applications in policy-related epidemiological
research include
-Evaluation of the effectiveness of health
interventions such as vaccine
-Pap test in preventing invasive cervical
cancer through early case detection
-Aspirin in reducing the risk of myocardial
infarction

45. Example: Effects of improvements in environmental
sanitation practices on diarrhoeal disease in Cebu
• Cases: children attending the clinic for
diarrhoea
• Controls: children attending the clinic for
respiratory disease
• Exposure: Good environmental sanitation
BALTAZAR, J. ET AL Can the case-control method be used to assess the impact of
water supply and sanitation on diarrhoea? A study in the Philippines. Bulletin
of the World Health Organization, 66 (5): 627-635 (1988)

46. Potential use in rapid
assessment
• Advantage in terms of time and
cost without compromising the
validity of the study
• Successful application largely
Conclusion: Case-control studies of the effect
of improved environmental sanitation on
diarrhoeal disease can be carried out rapidly,
at modest cost, and can produce valid estimates
of effect

47. Qualitative
methods

48. When to use?
Where there is a need to quickly understand
• Context
• Health related needs & challenges
• Community perceptions surrounding an
outbreak or health related event

49. Qualitative methods for REA
Focus group discussion
Key informant interview
Observation

50. FOCUS GROUP
DISCUSSION
(FGD)

51. FOCUS GROUP DISCUSSION
• In-depth discussion in which a small number of people (usually 8-12)
from the target population, under guidance of a moderator discuss
topics of importance for a particular study/project
• Participants: homogenous, should not know each other or subject of
the discussion in advance, selected purposively

52. • Full discussion is recorded
• Note-taker records non-verbal
aspects
• Transcription based on notes &
recordings, serve as basic data
for analysis

53. When to use FGDs?
• For studies that focus on social norms, expectations, values &
beliefs
• To explore controversial topics
• Understanding & solving unexpected problems in interventions

54. Strengths
Informal & supportive group of people with
similar backgrounds: ease, & encourage them to
express their views freely & frankly
Enables participants to elaborate on ideas

55. Because each participant is relating to a group
of people with similar characteristics, the
likelihood of participants giving answers they
think will please the interviewer is reduced
Less chance of questions being misunderstood

56. Limitations
Small number of participants
Limited generalizability
Group dynamics will be a challenge
Interpretation requires experienced analysts

57. KEY INFORMANT
INTERVIEW
(KII)

58. Key Informant Interviews
• KIs are an expert source of information
• A person with unique skills or professional
background on the issue being evaluated
• A person who knows what is going on in
the community & who has first-hand
knowledge about the community

59. When to
conduct
KIIs?
To get information about an
urgent issue in the community
To get information from people
with diverse backgrounds
To understand motivation &
beliefs of community
To discuss sensitive topics

60. Advantages
• Data can be obtained in a relatively shorter period
• Easy & inexpensive
• Provide opportunity to strengthen relationship with community
informants & stakeholders
• Can raise awareness, interest around an issue

61. Disadvantages
• Selecting the right key informants may be difficult
• Informants are unlikely to represent the view of those
individuals in their community
• They only disclose information that is politically acceptable

62. OBSERVATION

63. OBSERVATION

64. Participant observation

65. Advantages
• Natural behaviour can be
studied
• Closeness with the group: better
understanding
• Provide opportunity to learn
more about an event
Disadvantages
• Subjectivity
• May miss important issues
• Involvement in groupism
• Biased interpretation

66. Non-participant observation
• Researcher remains detached from the activity
under observation
• Simply watches and records what is going on

67. Advantages
• Neutrality maintained
• Freedom from groupism
• Often people do not feel shy to
disclose their secrets to a stranger
Disadvantages
• Subjectivity
• Lack depth of understanding
• Inconvenience to the
respondents

68. Transect walk

69. Transect walk
• It is a tool for observing the terrain &
everyday life in a given place
• Gives an overall view of the community &
helps identify things that may require
further investigation

70. • These walks are typically applied in villages for health &
sanitation planning
• Most effective when done with community members
• Time required: 2- 4 hours
• Materials required: Notebooks/paper, pens, markers, cameras
or phones, digital mapping tools

71. Learn about local
technology &
practices
Identifying &
explaining cause
& effect
relationships
Triangulating data
collected through
other methods
As a tool for
site selection
So, what can it be used for?

72. Select participants
Identify the route to be taken & the
time
Identify what you want to look for
on the walk
Add direct observation & interviews
Record & analyze the information
How to
do it?

73. E.g. Socio-economic and Bioresource assessment in
Khangchendzonga landscape, India

74. Advantages
• Can be used as a part of
community planning
• Good entry point when starting a
new project
• Better understanding of different
concerns
Disadvantages
• Challenging to find
representatives
• Requires time, willingness &
motivation

75. Geographical
Information
System (GIS)

76. GIS is not a newer concept
Areas with highest
concentration of
cholera cases were
within close
proximity to the
Broad’s street pump

77. Geographical Information System can be defined as a set of tools for
collecting, storing, retrieving, analysing and displaying spatial data

78. GIS terminologies
Spatial data
Features that have a
known location on
earth
Attribute data
The information linked
to the geographic
features describing
them

80. GIS software
ArcGIS
Geomedia
MapInfo Professional
Bharat maps
Bhuvan

81. DATAACQUISITION
• Analog maps
• Aerial photographs
• Satellite images
• Ground survey with GPS
• Reports & publications

82. (CASPER)
Community Assessment for Public Health
Emergency Response

83. Community Assessment for Public Health
Emergency Response (CASPER)
• Epidemiological tool to quickly assess the public health needs &
emergency response capabilities of communities following a disaster
• Designed by CDC
• Cross-sectional study design

84. • Two staged cluster sampling methodology
• Conducted by sending teams of volunteers to randomly selected
household to complete an in-person survey
• Can be used in disasters & in non-disaster settings

85. CASPER Example
To assess the level of household emergency preparedness,
Oakland County, Michigan (2012)
• Located near the Great Lakes
• Subject to winter storms & tornadoes,
power outages & chemical spills
• 1.2 million people reside approximately
50 miles from the nuclear plant

86. Sampling frame – 5,75,255 HHs in Oakland County
30 clusters were selected with a PPS & 7
HHs were selected within each cluster
85% - 3 day supply of non-perishable food
71% - copies of important document in a secure location
67% - own an first aid/emergency kit
65% - 3 day supply of water
92% - willing to shelter-in-place during radiation emergency

87. Uses of CASPER Estimate needs of a community
Assist in planning for emergency
response
Allocating scarce resources
Supporting requests for funding
during recovery operations

88. Benefits of REA
Priority setting
Appropriate allocation of
resources
Evaluation of impact
of services
Improves information-
improves decision
making

89. Recommendations
Training and workshops of health personnel in conducting REA
using LQAS and EPI cluster sampling methods
Awareness about the use of REA
Online training programs for using LQAS toolkit developed by
UNICEF and Core group

90. SUMMARY
REA – fast, cheap yet yields reliable results
Monitoring and evaluating health programs and health events
Proper training and dedication required

91. References
• Smith GS. Development of rapid epidemiologic assessment methods to evaluate
health status and delivery of health services. April 1992. Advisory Committee on
Health Research. WHO-SEARO.
https://apps.who.int/iris/bitstream/handle/10665/126920/sea_achr_18_inf.7.Pdf?se
quence=1&isAllowed=y. Last accessed on 9/10/21
• Anker M. Epidemiological and statistical methods for rapid health assessment.
World healthh statistics, quart 1991(44).

92. • Valadez JJ, Weiss W, Leburg C, Davis R. A Trainers Guide for Baseline Surveys
and Regular Monitoring. Using LQAS for Assessing Field Programs in Commuity.
December 2001. Available at: https://pdf.usaid.gov/pdf_docs/PNACN935.pdf.
Last accessed on 9/11/21.
• Davis RJ & Lederberg J. Public health system and emerging infections: assessing
the capabilities of the public and private sectors. 2000.
• Woodard SH Description and comparison of the methods of cluster sampling and
lot quality assurance sampling to assess immunization coverage. Department of
vaccines and biologicals. August 2001.

93. Rapid Appraisal
Rapid Reconnaissance
Informal methods
Exploratory survey
Rapid Assessment Procedures/Program (RAP)
Participatory Rural Appraisal (PRA)
Synonyms of REA!