Targeted Sampling of Heterosexuals: San Francisco, 20062007

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Targeted Sampling of Heterosexuals San
Francisco, 2006-2007
H. Fisher Raymond San Francisco Department of
Public Health HIV Epidemiology Section Behavioral
Surveys Unit
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Goal

• Sample heterosexuals living in targeted high-risk
  areas (HRA)1
• Conduct behavioral surveillance among high risk
  populations
• National HIV Behavioral Surveillance (NHBS)
• Estimate HIV prevalence
• Describe correlates of HIV risk

1. Premise HIV would be found in areas of low
income, high AIDS cases
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HRA Index
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Seeds and Recruitment

• Respondent Driven Sampling (RDS)
• 139 approached
• 45 (32) agreed to recruit
• 17 (38) seeds brought in at least 1 recruit
• 3-5 coupons per person
• Limits
• Only gave coupons to those living in HRA
• Initially gave coupons to current IDU, then
  stopped

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Eligibility

• 18 to 49
• Male or Female
• Had sex with minimum one opposite sex partner
  past 12 months
• Live in SF

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Figure 2. Targeted RDS Recruitment Chains San
Francisco, 2006.
Legend
Female
Male
Larger Nodes Seeds
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Analysis

• RDS is designed to produce a sample that can be
  statistically adjusted to account for recruitment
  biases
• But

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Figure 3. High Risk Heterosexual RDS in San
Francisco
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Analysis (cont)

• However, with the numerous bounds before and
  changes during recruitment (HRAs, IDUs, of
  coupons) data analyzed as a convenience sample

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Results Demographics

• Gender
• Male 37 (181)
• Female 63 (313)
• HS or less
• 69 (344)
• Employment
• Unemployed
• 42 (208)
• FT / PT
• 37 (183)
• Income
• lt10k
• 51 (248)

• Age
• 30 54 (267)
• Race / Ethnicity
• African American
• 75 (370)
• White
• 4 (21)
• Latino
• 11 (56)

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Results Risk Behaviors

• STD
• Any STD 18(89)
• Syphilis 1 (3)
• GC 5 (26)
• CT 12 (58)
• Herpes 3 (13)
• HPV 3 (14)

• Ever IDU
• 23 (114)
• IDU past 12 months
• 18 (92)
• MSM
• 5 (26)

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Results Risk Behaviors(among those not MSM or
IDU)

• 373 participants did not report IDU or MSM
  behavior
• 311 (83) reported any unprotected anal or
  vaginal intercourse

Males 242 (65) 3.6 mean partners (median 2.0,
IQR 3) 8,995 episodes of vaginal
intercourse 6,056 (67) were unprotected 662
occurrences of anal intercourse 592 (89) were
unprotected
Females 131 (35) 5.7 mean partners (median
2.0, IQR 2) 17,271 episodes of vaginal
intercourse 12,681 (73) were unprotected 1,984
occurrences of anal intercourse 1,562 (79) were
unprotected
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HIV

• 484 (98)Tested
• 8 (1.6) total HIV positive test results
• 6 (75) Ever IDU
• 1 (13) MSM/IDU
• 1 (13) Female
• No reported STD, CSW, minor drug use
• Reported UVI and UAI with 3 unknown status males
• Of the 8 HIV positives only 2 stated they
  previously tested positive.
• Out of 373 non MSM / non IDU
• 0. 27 HIV Prevalence

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Furthermore

• Heterosexuals 1 of SF AIDS Cases
• Vs. 13 in the US
• Young Womens Study- 1998
• 5 SF Bay Area Counties, low income neighborhoods,
  18-30
• 0.3 HIV Prevalence
• HeyMan- 2001
• 5 SF Bay Area Counties, low income neighborhoods,
  18-35
• 0.34 HIV Prevalence (Heterosexual ID men)

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Thoughts

• Heterosexuals living in HRAs are closely
  networked with other high-risk groups
• Disease transmission in HRAs may need input from
  other high-risk groups
• Heterosexual HIV is not non-existent however
  transmission may be exceedingly rare when not
  fueled by other high-risk groups