Rapid Community Needs Rapid Community Needs AssessmentAssessment

Bonnie Henry, MD, FRCPC

Public Health CBRN course

Goals of SessionGoals of Session

To learn the principles of rapid community risk assessment using modified cluster sampling methods

To understand when this technique may be useful in response or recovery from a disaster

Goals of Rapid Needs AssessmentGoals of Rapid Needs Assessment

To rapidly obtain population-based estimates of need in the early aftermath of a disaster

Should also be a way of reaching the affected areas with information about relief efforts and services

HistoryHistory

Based on methods developed by the WHO for estimating immunization coverage in the EPI program

Used to estimate community impact of Hurricane Andrew in South Florida in 1992

Also used after the Sept 11, 2001 attacks in NYC to assess needs in residents of Lower Manhattan

Who would use the dataWho would use the data

Government organizationsDisaster relief organizations (Red

Cross etc)Provincial, regional and local public

health and healthcare organizationsLaw enforcementUtilities, (especially electricity, water)Media, etc.

Cluster Sampling MethodsCluster Sampling Methods

Systematic sampling of 30 ‘clusters’

Create a grid over the area to be sampled– ¼ mile squares on

street map

Assign each square or ‘cluster’ a number

Cluster Sampling MethodsCluster Sampling Methods

Determine the interval you need to end up with 30 clusters to sample– For example if you have 120 squares in your

grid you will have an interval of 4 (120/30=4)

Randomly determine where to start– In this case pick a number between 1 and 4– You can use a random number generator or

the serial number on a $5 bill

Select your 30 clusters

Cluster Sampling MethodsCluster Sampling Methods

Go to the centre of the first cluster (i.e. square or cluster 3 on your map)

Determine your sampling unit– Usually people or households

Determine the number of units to be sampled in each cluster (i.e. 10 households)

Proceed in a randomly picked direction to the first occupied household

Cluster Sampling MethodsCluster Sampling Methods

Interview the first adult at the occupied residence

Then go consecutively to the next occupied household until you have reached 10 in that cluster

If a multi-unit dwelling or apartment building pick first occupied unit for interview

Move on to next selected cluster

Example: Systematic samplingExample: Systematic samplingExample: systematic sampling

Source: D. Coulombier, Epicentre

Source: MSF

Sampling methods – organization of sampling units; Cegrane Sampling methods – organization of sampling units; Cegrane camp, Cegrane, Macedonia - 1999camp, Cegrane, Macedonia - 1999

Source; B. Woodruff, US-CDC

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

37 38 39 ....

Sampling interval = 12; Starting number = 3; Cycle = 3

Source: EPIET

Interview MethodsInterview Methods Interview team usually 3-4 people including an

epidemiologist and volunteer interviewers – from medical schools, public health staff etc.

Use a simple questionnaire Ensure team able to provide information on:

– Location of medical treatment, supply distribution sites

– Provide preventive health messages on food, water safety, handwashing, injury prevention etc.

Sample QuestionsSample Questions How many and what percentage of surveyed

households reported the following? – Not enough food – No running water – No electricity – No heat/air conditioning (in temperature extremes) – No functioning toilet – No telephone – No car or truck – Injured resident(s) – Ill resident(s) – Resident(s) in need of medical care – Resident(s) unable to obtain needed medications – Resident(s) in need of counseling  – Resident(s) with special needs – Displaced from home

Time frame for initiating studyTime frame for initiating study

After ground transportation is restored

Approximately 3 and 10 days after the event for severely affected areas

Assessments of less severely affected areas phased in as possible

BenefitsBenefits

Practical and standardized methods allow for rational assessment (not based on rumours only)

Gives a picture of what needs are and helps direct relief operations– E.g. switch from mass casualty trauma

services to primary care and preventive services

Can monitor over time

““Being roughly right is generally Being roughly right is generally more useful than being precisely more useful than being precisely wrong”wrong”

Guha-Sapir, D. Rapid assessment of health needs in mass emergencies: Review of current concepts and methods. World Health Stat Q. 1991;44:171-181.