1239. Transmission Clustering Among Newly Diagnosed HIV Positive Patients in Chicago, 2008-2011
Session: Oral Abstract Session: HIV: Detection, Linkage, and Utilization
Saturday, October 5, 2013: 10:54 AM
Room: The Moscone Center: 250-262
Background: Despite wide availability of diagnostic testing and effective therapy, United States HIV incidence has failed to decline.  Assessing for transmission clusters via comparison of HIV pol sequences provides supplemental HIV epidemiologic data that can be used to inform prevention efforts.  We describe the first such assessment for transmission clustering among newly diagnosed HIV patients in Chicago.

Methods: The Ruth M Rothstein CORE Center, as part of the Variant, Atypical, and Resistant HIV Surveillance project for the Center for Disease Control, obtained HIV genotypes on patients presenting within 90 days of diagnosis to assess for transmitted drug resistance.  After stripping patient identifiers from the dataset, we assessed for transmission clustering among HIV pol sequences collected between January 2008 and May 2011.  Sequences were compared via progressive pairwise alignment.  We used the Tamura-Nei neighbor joining method to determine genetic distance and construct an un-rooted phylogenetic tree.  We defined a cluster as > 2 sequences among which each sequence had at least one partner within a genetic distance of ≤ 0.015.  We used multivariate regression to assess for demographic features correlated with patient membership in a transmission cluster. 

Results: We included HIV pol sequences from 920 CORE Center patients newly diagnosed with HIV between 1/2008 and 5/2011.  Of those patients, 77% were > 25 years old, with a median age of 34.5 years; 75% were male; 67% were Black, 23% Hispanic, and 9% White.  Phylogenetic analysis demonstrated that 124 patients (14%) grouped into 26 clusters, the largest having 21 members.  In multivariate regression, age <25 (OR=2.99; 95% CI 1.99-4.50), Black race (OR=3.99; 95% CI 2.26-7.07), and male gender (OR=3.66; 95% CI 1.95-6.86) were associated with membership in a transmission cluster.  Of the clustered patients, 77% reported male sex with male as their HIV risk factor.

Conclusion: These results confirm public health surveillance data demonstrating high rates of HIV transmission among young Black males in the US and Chicago.  Further breakdown of these clusters with respect to HIV transmission risk factor along with geographic coding may help improve Chicago’s HIV prevention efforts.

Sarah Hoehnen, DO1,2, Ronald Lubelchek, MD1,2,3, Anna Hotton, PhD, MPH4, Stacey Kincaid, MPH3, David Barker, MD1,2,3 and Audrey French, MD1,2,3, (1)Rush University Medical Center, Chicago, IL, (2)John H. Stroger, Jr. Hospital of Cook County, Chicago, IL, (3)Ruth M. Rothstein CORE Center, Chicago, IL, (4)Chicago Developmental Center for AIDS Research (D-CFAR), Chicago, IL

Disclosures:

S. Hoehnen, None

R. Lubelchek, None

A. Hotton, None

S. Kincaid, None

D. Barker, None

A. French, None

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