Spatial Analysis of HIV/AIDS mortality events in aSpatial Analysis of HIV/AIDS mortality events in a rural South Africa population between 2000-2006

Elias Namosha 1, 3, Frank Tanser ², Benn Sartorius1

1Witwatersrand University, School of Public Health, Faculty of Health Sciences,7 Y k Rd P k 2193 S h Af iYork Rd, Parktown 2193, South Africa2Africa Centre for Health and Population Studies, P.O. Box 198, Mtubatuba, 3935, South Africa3PNG Institute of Medical Research , P.O. Box 400, Maprik 533, ESP, PNGf , , p , ,

23nd September, 2008 

OutlineOutline

• IntroductionAi & Obj ti• Aim & Objectives

• Methodology• Results• Discussion & Conclusions• Acknowledgements

Introduction (1)

Global estimation of HIV/AIDS: Global estimation of persons living with HIV/AIDS 2005(millions); total 40.3 (36.7-45.3) million. (Source: UNAID/WHO, 2005)

HIV/AIDS is the major burden globally, affecting an estimated 65 million people ld id d th 25 illi h di d f AIDSworldwide and more than 25 million have died of AIDS

Introduction (2)

In Africa (African continent) it is a leading cause of mortality and morbidity

South Africa has more people living with HIV/AIDS then any other country in the world. Inrural South Africa HIV/AIDS is a major health problem

It is now becoming necessary to look at new public health approaches to help manageIt is now becoming necessary to look at new public health approaches to help manage HIV/AIDS at the local, provincial or national level and GIS can be an appropriate approach

Spatial clustering (GIS) of AIDS mortality has never been done before at the community l l thi t d i th fi t t dd thi i th Af i C t HDSS d tlevel so this study is the first to address this using the Africa Centre HDSS data

Study Aim & Objectives

Aim: To apply GIS tools to investigate and demonstrate how GIS and spatial scan statistic technology can be optimized for public health management and intervention

Primary Objectives

1 To describe the mortality profile of the Africa Centre demographic surveillance site1. To describe the mortality profile of the Africa Centre demographic surveillance site (ACDSS) population with a particular focus on AIDS mortality between 2000-2006

2. To map the distribution of adult AIDS and all-cause mortality across the DSS (≥15 years) using spatial scan statistic and GIS technology

Methodology (1)

St d d l ti iStudy area and population size

Africa Centre HDSS established in 2000

Area = 438 km2 with pop. approx 85,000 &(11,000 household)

Population = both resident and non-residents

Pop. density ranging from 20-3000 people/km2

Source of income is waged employment andstate pensions > agriculture

In 2006, approx 77% of households have accessto piped water and toilet facilities

Methodology (2)

Study design and database

A d d t l i t d i d t f th l ti b dA secondary data analysis study using data from the population-based longitudinal cohort study

Exposure data and mortality events from the ACDIS (Africa Centre demographic posu e data a d o ta ty e e ts o t e C S ( ca Ce t e de og ap cinformation systems) database during 2000-2006 were used

Database stores data on registered subjects or individuals, physical structures(e g homesteads clinics and schools) and household(e.g. homesteads, clinics and schools) and household

Adult residents (≥ 15yrs) both males and females forms the study sample

Methodology (3)

Cluster detection method

Mortality events and person-exposure were aggregated by homestead using MapInfo Program version 7

Analyses were performed for adults (≥15 years) across the two time periods (2000-03Analyses were performed for adults (≥15 years) across the two time periods (2000 03 and 2004-06). All results were adjusted for age and sex

A spatial scan statistic analysis implemented in SaTScan 7.0.3, was used to identify t ti ti ll i ifi t t lit l t ( 0 05)statistically significant mortality clusters (p≤0.05)

The circle with the maximum likelihood is the most likely cluster (p≤0.05) - least likely to have occurred by chancey

Causes of deaths by year and sex for adult population (≥15yrs) Results (1)

AIDS mortality clusters for time period 2000-03 and 2004-06 (≥15yrs)Results (2)

Standardized maps across the two time periods 2000-03 & 2004-06Results (3)

All-cause mortality cluster for time periods 2000-03 and 2004-06 Results (4)

Mapping is a powerful tool for helping people visualize the geographic distribution of h lth bl

Discussion & Conclusion

health problems

GIS and spatial scan statistic was used as a quick research tool to investigate potential mortality clusters in the Africa Centre DSSp y

Cluster detection analysis can be an appropriate approach to identify critical HIV/AIDS mortality locations for investigation and interventions to be carried out

Further work (socio-economic, health seeking behaviour) is needed to understand the underlying mechanisms responsible for the spatial clustering tendencies (p≤0.05)

This study may be regarded as a first step in prioritizing areas that needs further investigation and public health effort in the Africa Centre DSS

With this sort of analytical study health officers can come up with better strategicWith this sort of analytical study health officers can come up with better strategic health plans for intervention now and in the future

Acknowledgements

• Tropical Disease Research (TDR/WHO) Grant, Geneva INDEPTH Net ork• INDEPTH Network

• Wits University, School of Public Health• Staff & Management of Africa Centre HDSS • Dr. Ivo Mueller (PNGIMR)• Prof. Peter Siba ( PNGIMR)• Wosera HDSS,PNG (PNGIMR)Wosera HDSS,PNG (PNGIMR)

Thank you…