1) The study identified 19 distinct spatial clusters of people living with HIV/AIDS in Texas based on their risk of transmission using spatial scan statistics. 2) 39.2% of the total 46,301 HIV/AIDS cases in Texas were found within these clusters. 3) The clusters were located primarily in major metropolitan areas like Houston, Dallas, Fort Worth, Austin, San Antonio, and El Paso.

1. Spatial clusters of people living with HIV/AIDS by risk of transmission in Texas Sonia Arbona PhD Praveen R. Pannala, MD, MPH Sharon K. Melville, MD, MPH May 26, 2009

8. Results Cluster Statistics Table 1. Spatial clusters of HIV/AIDS in Texas by HIV mode of transmission in 2008 Mode of Transmission Cluster Location Observed cases Expected cases Relative risk estimate Log-likelihood ratio P value IDU 1 Houston 1196 358.4 3.98 674.95 0.001 2 Fort Worth 108 8.15 13.49 180.09 0.001 3 Dallas 182 39.31 4.75 138.1 0.001 4 El Paso 30 4.4 6.84 32.02 0.001 5 Dallas 29 5.54 5.26 24.61 0.001 6 Waco 35 8.54 4.12 22.97 0.001 MSM 1 Dallas 4681 837.95 6.53 4501.07 0.001 2 Houston 4514 1132.83 4.57 3086.00 0.001 3 Austin 1585 711.75 2.30 410.11 0.001 4 San Antonio 390 70.93 5.56 347.54 0.001 5 El Paso 166 51.39 3.24 80.28 0.001 MSM/IDU 1 Houston 358 64.78 6.13 333.79 0.001 2 Dallas 262 69.62 4.03 161.25 0.001 3 Austin 198 53.40 3.90 118.44 0.001 4 Fort Worth 57 15.33 3.77 33.46 0.001 HRT 1 Houston 3858 1173.57 4.68 2353.98 0.001 2 Dallas 299 68.11 4.49 214.09 0.001 3 Dallas 179 61.59 2.94 74.25 0.001 4 Fort Worth 46 14.28 3.23 22.14 0.001

9. Results Demographic Characteristics clustered not clustered 38.9% 61.1% Figure 2

10. Results Spatial Clusters in Dallas – Fort Worth

11. Results Spatial Clusters in Central Texas

12. Results Spatial Clusters in Houston

13. Comments and Future Directions