1. STIs in a multi-site sample of high-risk, substance-using MSM:
Baseline results from Project MIX
Gordon Mansergh, PhD
National STD Prevention Conference
March Chicago
The findings and conclusions in this report are those of the author and do not necessarily represent the views of the Centers for Disease Control and Prevention

3. Overview Study Background Sample Characteristics
STIs & Associated Factors
Summary & Implications

4. Substance-using MSM in the U.S.
Background
Substance use is associated with sexual risk for STI transmission among MSM
Heightened STIs among MSM samples in this decade
Objective
Better understand factors associated with reported STIs among high risk, substance-using MSM

5. Project MIX Study Group
CDC (Division of HIV/AIDS Prevention) –
Gordon Mansergh, Steve Flores, Raekiela Taylor, Cathy Zhang, David Purcell, Pilgrim Spikes, other data management and analysis staff et al.
Chicago (UIC & Howard Brown Health Center) –
David McKirnan, Jenny Hopwood et al.
Los Angeles (Health Research Association) –
Sharon Hudson, Bobby Gatson et al.
New York City (NY Blood Center & NY Academy of Medicine) –
Beryl Koblin, Victoria Frye, Krista Goodman et al.
San Francisco (San Francisco DPH) –
Grant Colfax, Tim Matheson et al.

6. Project MIX Uniqueness
Large, multi-city sample with very high risk eligibility:
Unprotected anal sex with a man in the past 6 months
Anal sex with a man while drunk or high in the past 6 months
Diverse participant “mix”:
HIV+ and HIV- men
Over-sampled Black and Latino men
Different substances of choice and patterns of use
Variety of income and education levels, and age groups
Variety in non/gay identification and born in US

7. Methods Recruitment: staff outreach, ads, and snowball in 2005-6
Measurement: ACASI self-reported demographic and behavioral characteristics at Baseline
HIV status
STIs in past 12 months
Substance use during most recent anal sex encounter with non-primary partner in past 3 months
Analysis: Multivariate logistic regression for STIs (models include all listed variables)

8. Table 1. Baseline sample characteristics for Project MIX (n=1540)
Sample Characteristics % (n)
HIV-status (self-reported)#
Negative (685)
Positive (724)
Unknown (131)
Sexual orientation (self-reported)#
Gay/homosexual/queer 84 (1288)
Bisexual (221)
Other (31)
Race/ethnicity
White (589)
Black (492)
Latino (293)
Other (166)
Age group (years)
(409)
(525)
(606)
Education
High school diploma or less 32 (484)
Some post-high school education 34 (529)
College degree or higher 34 (527)
Study site
Chicago (411)
Los Angeles (356)
New York City 23 (362)
San Francisco 27 (413)
Born outside United States 14 (223)
#For subsequent analyses: HIV-unknowns are combined with HIV-negative men; bisexuals are combined with “other” self-identification

9. Table 2. Self-reported STIs at baseline for Project MIX (n=1540)
Reported having an STI in the past 12 months:
33% any STI
13% gonorrhea
11% syphilis
8% Chlamydia
14% other/undetermined STI

10. Table 3. Behavior during most recent anal sex encounter with a non-primary partner for Project MIX at baseline (n=1540)
Behavioral Characteristics % (n)
Sexual risk behavior
Unprotected receptive (URA) 39 (600)
HIV-discordant URA (DURA) 21 (326)
Unprotected insertive (UIA) 37 (563)
HIV-discordant UIA (DUIA) 19 (291)
Substance use before or during sex 77 (1108)
Alcohol (893)
Other drug 58 (892)
Marijuana 23 (352)
Methamphetamine 18 (285)
Poppers/amyl nitrite 13 (208)
Crack 13 (206)
Cocaine (139)
Viagra/Cialis/Levetra 8 (119)
Other drugs 12 (189)
Multi-substance use (>1 substance) 46 (710)
Substances with <5% use prevalence were combined into “other” substance use, #Age groups used to categorize partners as Younger or Older than the respondent were 18-29, 30-39, and 40 or more years old.

11. Table 4a. Sample characteristics and reported STIs in the past 12 months at baseline for Project MIX participants (n=1540)
Variables associated with STIs in past 12 months (multivariate results
Any STI
Sample Characteristics OR (CI)
Reported HIV-status
Positive ( )
Negative/unknown (ref)
Reported sexual orientation
Gay/homosexual
Bisexual/other (ref)
Race/ethnicity
Black
Latino
Other
White (ref)
Age group (groups)
( )
30-39
40+ (ref)
Education
HS diploma or less
Some post-HS educ
College deg or more (ref)
Born in United States
Not born in US (ref)
Substance use during last sex with a non-primary partner
Alcohol use ( )
No alcohol use (ref)
Drug use
No drug use (ref)
Multi-substance use (2+)
No multi-subst use (ref)
STI, sexually-transmitted infection; multivariate analyses include all variables listed; OR=Adjusted Odds Ratio; CI=95% confidence interval

12. Table 4b. Sample characteristics and reported STIs in the past 12 months at baseline for Project MIX participants (n=1540)
Variables associated with STIs in past 12 months (multivariate results)
Any STI Gonorrhea
Sample Characteristics OR (CI) OR (CI)
Reported HIV-status
Positive ( ) 1.6 ( )
Negative/unknown (ref)
Reported sexual orientation
Gay/homosexual
Bisexual/other (ref)
Race/ethnicity
Black
Latino
Other
White (ref)
Age group (groups)
( ) 1.7 ( )
30-39
40+ (ref)
Education
HS diploma or less
Some post-HS educ
College deg or more (ref)
Born in United States
Not born in US (ref)
Substance use during last sex with a non-primary partner
Alcohol use ( )
No alcohol use (ref)
Drug use
No drug use (ref)
Multi-substance use (2+)
No multi-subst use (ref)
STI, sexually-transmitted infection; multivariate analyses include all variables listed; OR=Adjusted Odds Ratio; CI=95% confidence interval

13. Table 4c. Sample characteristics and reported STIs in the past 12 months at baseline for Project MIX participants (n=1540)
Variables associated with STIs in past 12 months (multivariate results)
Any STI Gonorrhea Syphilis
Sample Characteristics OR (CI) OR (CI) OR (CI)
Reported HIV-status
Positive ( ) 1.6 ( ) 3.9 ( )
Negative/unknown (ref)
Reported sexual orientation
Gay/homosexual
Bisexual/other (ref)
Race/ethnicity
Black ( )
Latino
Other
White (ref)
Age group (groups)
( ) 1.7 ( )
30-39
40+ (ref)
Education
HS diploma or less
Some post-HS educ
College deg or more (ref)
Born in United States
Not born in US (ref)
Substance use during last sex with a non-primary partner
Alcohol use ( ) 0.5 ( )
No alcohol use (ref)
Drug use
No drug use (ref)
Multi-substance use (2+)
No multi-subst use (ref)
STI, sexually-transmitted infection; multivariate analyses include all variables listed; OR=Adjusted Odds Ratio; CI=95% confidence interval

14. Table 4d. Sample characteristics and reported STIs in the past 12 months at baseline for Project MIX participants (n=1540)
Variables associated with STIs in past 12 months (multivariate results)
Any STI Gonorrhea Syphilis Chlamydia
Sample Characteristics OR (CI) OR (CI) OR (CI) OR (CI)
Reported HIV-status
Positive ( ) 1.6 ( ) 3.9 ( )
Negative/unknown (ref)
Reported sexual orientation
Gay/homosexual
Bisexual/other (ref)
Race/ethnicity
Black ( ) 0.5 ( )
Latino
Other
White (ref)
Age group (groups)
( ) 1.7 ( )
30-39
40+ (ref)
Education
HS diploma or less
Some post-HS educ
College deg or more (ref)
Born in United States
Not born in US (ref)
Substance use during last sex with a non-primary partner
Alcohol use ( ) 0.5 ( )
No alcohol use (ref)
Drug use
No drug use (ref)
Multi-substance use (2+)
No multi-subst use (ref)
STI, sexually-transmitted infection; multivariate analyses include all variables listed; OR=Adjusted Odds Ratio; CI=95% confidence interval

15. Summary & Implications
These are indeed high risk MSM to be targeted for risk reduction (i.e., UA and STIs)
HIV+ status is associated with several STIs, particularly syphilis
Younger age is associated with gonorrhea
Black race is associated with syphilis, and white race with Chlamydia
Implications
Even among very high risk, substance-using MSM, subgroups of men should be targeted with STI risk reduction messages
However, all MSM who use substances during sex could potentially benefit from risk reduction efforts

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