Geographic Information Systems in Public Health

• Set of interacting components that use spatial reference data and health-related information to analyze and synthesize large quantities of data and information to support, orient, and evaluate public health interventions and decision-making in a territory or defined space for a specific time period.

Information Systems Technology

Epidemiology/(Bio)Statistics

Geography/Cartography

GIS-PH

Geographic Information Systems in Public Health

Enrique LoyolaRisk Assessment and Management Unit

Sustainable Development and Health AreaPan American Health Organization (PAHO/WHO)

Montevideo, Uruguay, 15 February 2007

Components of a Geographic Information SystemComponents of a Geographic Information SystemComponents of a Geographic Information SystemComponents of a Geographic Information System

InputInputInputInput StorageStorageStorageStorage ProcessProcessProcessProcess OutputOutputOutputOutput

Some Uses of GIS in HealthSome Uses of GIS in Health

• Determination of health situation in an areaDetermination of health situation in an area

• Surveillance of health eventsSurveillance of health events

• Generation and analysis of research hypothesisGeneration and analysis of research hypothesis

• Identification of high risk groupsIdentification of high risk groups

• Planning and programming of health servicesPlanning and programming of health services

• Environmental risk analysisEnvironmental risk analysis

• Monitoring and evaluation of health interventionsMonitoring and evaluation of health interventions

Evaluation of interventions and public health programs

Malaria and Health services coverage in Peten, Guatemala

Public Health Methods for GIS and Spatial Analysis

Critical Areas

HSA SERVICESENVIRONMENT

Pop. DistributionGeo-referencing, Density,

interpolation Morbidity Std Index, 2001

Z score =IEM

Relief/TopographySlope, aspect,

Spatial Analyst (GRID, TIN),

Health ServicesGeo-codification

HospitalsGRID Distances

Spider DiagramsCatchment's

area

Roads Classification

DistancesSlopes

Spatial Tools (Assign slope

values ) CesamoGeo-coding

Spider DiagramsDistances

Catchment's area

Cesar

NBI Municipal Geo-

coding

Environmental risksLandslides and flooding

areasQuery and spatial

selectionsSpecific Tool

Zscore =ICAInterpolation

Accessibility Index

Thiessen Polygons, Buffers Coverage

Land UseSpatial quieries

Overlapping Environmental Risks and Population

• Flooding High Risk (around 1 km from rivers)

– 458 communitites– and 824 889 people

• High Risk of Landslides – 90 Communitites – and 53 501 people.

Unmet Basic Needs (NBI), Illiteracy and Municipal Malnutrition

NBI municipal Index:• Low quality material dwellings (waste materials walls)• Dwellings without basic sanitation services (drinking water and sewerage)• Crowding (more than 3 people per room).• Households with school age children (7 - 12 y) not in the school• Household with high economic burden (more than 3 people depending on one worker and

less than 3 years of study among the parents)

NBI

Illiteracy

Malnutrition

Morbidity Standardized Index

• Sum of normalized values of morbidity indicators (Z score)

• RATES X 100 000:

– Pneumonias Rate among children under 5

– Malaria Rate Dengue Rate

– Tuberculosis Rate

– AIDS Rate

– Diabetes Rate

Communities in geographic catchment’s area

Thiessen Polygons

catchment’s area

cover:

• 19 communities

and 148 979 people

• 148 979 / 5 = 29

794 families

Beyond 8 km

Buffer of CESAMOS

are:

• 1 883 communities

• 2 085 862 people

Low accessibility critical areas

Accessibility Index (ICA constructed with SIGEpi 1.0)• Distances (km) and slopes to nearest facility• Slopes Calculation of z scores • Linear interpolation of community's ICA Values Selection of 2 Std Deviation values of

ICA to define critical areas RESULT:

In Low Accessibility Critical Areas there are 807 communities with en 638, 856 inhabitants.

Cluster detection:

Multicentric data compilation and geo-processing

Spatial Auto-correlation• Global and Local• Box Map (outliers)• Probability/significance map• Moran’s scatter plot

Spatial Clusters of Severe Growth RetardationSpatial Clusters of Severe Growth Retardation

Clusters of Severe Growth Retardation in GT, HN and ESClusters of Severe Growth Retardation in GT, HN and ES

Choroplet map, cuartil intervals of SGR. Moran’s I = 0.71, p<0.01)Choroplet map, cuartil intervals of SGR. Moran’s I = 0.71, p<0.01)LISA Map. Local Indicator of Spatial AutocorrelationLISA Map. Local Indicator of Spatial Autocorrelation

Moran’s Scatter-Plot. SGR vs. Spatial Lag SGR.Moran’s Scatter-Plot. SGR vs. Spatial Lag SGR. Moran’s Scatter-Map. High significance clusters of SGR. Moran’s Scatter-Map. High significance clusters of SGR.

Severe Growth Retardation in GT, HN and ES. Digital Elevation Modelin GT, HN and ES. Digital Elevation Model

What is SIGEpi?What is SIGEpi?

It is a Geographic Information System (GIS) designed for applications in Epidemiology and Public Health, including specific analytical procedures for:

• mapping of health indicators,

• equity and poverty measurement,

• health situation and spatial analysis,

• public health surveillance,

• epidemiological assessment,

• and exploratory data analysis.

Cartographicdatabase

Non-spatialDatabase

Databaseengine.

Spatial Dataengine

Analyticalcomponent

Map component

Chart component

Result component

ApplicationProject/Persistence component.

ProjectfilesXML/SIGEpiXML

Layout component

Basic Architecture of SIGEpi

Common GIS FeaturesCommon GIS Features• GIS generic functionsGIS generic functions– Map handling tools: zoom in, zoom out, Map handling tools: zoom in, zoom out, pan, identity, distance measure.pan, identity, distance measure.– Layer Control.Layer Control.– Selection by geometric objects, Selection by geometric objects, attributes and other layers.attributes and other layers.– Map labels.Map labels.– Thematic maps: Ranges, Graduated Thematic maps: Ranges, Graduated Symbols, Dot Density, Bars and Pie, Value Symbols, Dot Density, Bars and Pie, Value map.map.– Charts: Bars, Stacked Bar, Lines, Charts: Bars, Stacked Bar, Lines, Scatterplot, Boxplot. Scatterplot, Boxplot. – LayoutLayout • Database FormatsDatabase Formats

– MicroSoft AccessMicroSoft Access– Import/Export other Import/Export other formats: formats: dBase, FoxPro,

Excel, EpiInfo 6 (.rec)

• GGeoprocessing functionseoprocessing functions– Spatial Queries Spatial Queries – Point plot from data table, using Point plot from data table, using Lat/Long variables.Lat/Long variables.– Simple and concentric Buffers.Simple and concentric Buffers.– Spider diagram maps.Spider diagram maps.

• Cartographic Data Cartographic Data FormatsFormats– ESRI Shapefiles, ESRI ESRI Shapefiles, ESRI Coverage, CAD Drawing, Coverage, CAD Drawing, VPF, EpiMap Bnd (ver 1 & 2VPF, EpiMap Bnd (ver 1 & 2– MrSID, GRID, & other MrSID, GRID, & other common raster/image formatscommon raster/image formats..– Simple and concentric Simple and concentric Buffers.Buffers.– Spider diagram maps.Spider diagram maps.

Methods & Analytical ProceduresMethods & Analytical Procedures

• Statistics & Exploratory Statistics & Exploratory functionsfunctions

– Descriptive Statistics Descriptive Statistics (measures of central trends and (measures of central trends and dispersion)dispersion)– Frequency DistributionFrequency Distribution– Correlation AnalysisCorrelation Analysis– Regression Analysis simple Regression Analysis simple and multiple linear regressionand multiple linear regression– Calculation of RatesCalculation of Rates–Standardization of Rates - Standardization of Rates - Direct & Indirect methodsDirect & Indirect methods– Spatial smoother of Rates & Spatial smoother of Rates & Proportions. Proportions.

• Cluster detection functionsCluster detection functions– Spatial Smoother. Empirical Spatial Smoother. Empirical Bayes estimators, global and Bayes estimators, global and local approach)local approach)– Spatial Autocorrelation & Spatial Autocorrelation & Local Indicators of Spatial Local Indicators of Spatial Autocorrelation. Autocorrelation. – Outliers Map.Outliers Map.– Time-Space interaction of Time-Space interaction of Health events (Knox method).Health events (Knox method).

• Public Health functionsPublic Health functions– Identification of Critical areasIdentification of Critical areas– Construction of a Compound Construction of a Compound Index (CENDES/PAHO Index (CENDES/PAHO Approach) Approach) – Exposure-Effect measurement Exposure-Effect measurement of association in of association in epidemiological studies.epidemiological studies.– Assessment of access to Assessment of access to health services. Spider health services. Spider diagrams. diagrams.

SIGEpi Manual and Help SystemSIGEpi Manual and Help System

PAHO SIGEpi Web Site: PAHO SIGEpi Web Site: http://ais.paho.org/SIGEpi

PAHO/JHU Epidemiologic applications of PAHO/JHU Epidemiologic applications of geographic information systems coursegeographic information systems course

Contacts at PAHO

Dr. Enrique Loyola: loyolaen@paho.orgIng. Ramón Martínez: martiner@paho.org

Organización Panamericana de la Salud525 23rd Street, NW

Washington, DC 20037