High Risk Sharing Behaviors: The Effect of Sex within

Injecting Partnerships

Meghan D. Morris, PhD, MPHPostdoctoral Research Fellow

Department of Epidemiology & BiostatisticsUniversity of California, San Francisco

Mmorris@psg.ucsf.edu

AcknowledgementsCo-Authors

Jennifer Evans, Michelle Yu, Alya Briceno, Martha Montgomery, Kimberly Page,

Judith HahnCollaborators

Paula Lum, Michael Busch, Eric Delwart, Leslie Tobler

Funding (NIH-NIDA)

R01-DA016017, R01-DA031056, K01-DA023365

The research participants and staff!

Background

• Research has supported the notion that relationships between IDU, rather than individual risk behaviors alone, contribute significantly to the disease transmission patterns in IDU populations.

Few studies have considered both the individual and their injecting partner when identifying factors associated with

drug using behaviors.

• For most young injection drug users (IDU), injecting drugs is a highly social activity.

Study Objectives• To characterize injecting partnerships within a

cohort of young (<30 years) IDU

• To measure the prevalence and estimate partnership characteristics associated with two high risk sharing behaviors: (1) receptive syringe sharing(2) receptive cooker use

Study Hypothesis

1. Female-Male injecting partnerships are at greater odds of high risk sharing behaviors than Male-Male injecting partnerships.

2. Partnerships engaging in both injection and sexual behaviors are at even greater odds of high risk sharing behaviors compared to partnerships engaged in only injecting.

The UFO “Partnership Study”Study Design:• Prospective study of

hepatitis C (HCV) transmission and acquisition within injecting dyads

• Injecting partnerships were interviewed monthly for up to 6 months; with possibility of reenrollment

• San Francisco, CA USA

Injecting Partnership Definition:1. Injected together ≥ 5x in

past monthAND 2. HCV RNA discordant upon

enrollment

Eligibility did not require that drugs or injection equipment were shared

HCV+ Index

HCV- Partner

Analytic MethodsStatistical Analysis:

Multilevel Generalized Estimating Equations were used:– To examine the effect of

partnership type on high risk sharing behaviors.

• Egocentric analysis focused on the “at risk” HCV-negative partner

Outcomes:1. Recent Receptive Syringe Sharing

“Within the past 30 days, did you inject with a needle that your partner had already used, even if by accident or mistake?”

2. Recent Receptive Cooker Sharing“Within the past 30 days, was there any time that your partner’s previously used needle had been used with a cooker before you used that cooker?”

Receptive Risk

HCV+ Index

HCV- Partner

28% receptive cooker sharing

17% receptive syringe sharing

Study SampleBaseline Sample

Baseline + Followup Sample

58 “at risk” partners

58 Injecting Partnerships

251 interviews among “at risk” partners

Median of 4 interviews per partnership

9 new HCV infections

85% agreement in reporting of high risk sharing behaviors within partnerships

• Median age 24 (IQR: 22-27)

• Median duration of injection drug use was 6 years (IQR:3-9)

Baseline characteristics of “at risk” partners (n=58)

Ever been in drug

treatment

Ever been in jail/prison

WhiteFemale0

10

20

30

40

50

60

70

80

90

100

Perc

ent (

%)

Baseline Partnership-level Characteristics (n=58)

35%

62%

4%

Gender Composition of Inject -ing Partnerships

Male-Male in-jecting part-nershipMale-Female injecting partnershipFemale-Female injecting part-nership

• 34% of injecting partnerships were engaged in sexual behaviors

• 56% always pooled money to buy drugs

• 80% lived together

• Median duration of injecting partnership was 4 months (IQR:2-12)

• Median time known partner was 10 months (IQR: 4-18)

Bivariate associations with high risk sharing behaviors

Receptive Syringe Sharing(n=251)

Receptive Cooker Sharing(n=251)

OR (95% CI) OR (95% CI)Male-Female injecting partnership vs. Male-Male injecting partnership

1.8(0.4-7.9)

1.1 (0.4-3.2)

Sex with injection partner in past month 2.8 (1.1-7.6)

2.5 (1.1-6.2)

Age at first injection drug use (per year increase)

0.9(0.9-1.9)

0.9 (1.0-1.3)

Biological Sex is Female vs. Male 1.1(0.3-3.4)

0.8(0.3-2.9)

Known partner for ≥ 1 year vs. <1 year 1.1 (0.5-2.7)

0.6 (0.3-1.4)

*GEE models with link logit, controlling for multiple partnerships

Recent sex with injecting partner independently associated with high risk sharing behaviors

Receptive Syringe Sharing(n=251)

Receptive Cooker Sharing(n=251)

OR (95% CI) AOR (95% CI) OR (95% CI) AOR (95% CI)

Sex with injection partner in past month

2.84 (1.06-7.57)

4.01 (1.30-12.36)

2.50 (1.02-6.17)

4.29 (1.40-13.19)

Age at first injection drug use (per year increase)

0.96(0.91-1.91) ns 0.88 (1.01-

1.29) ns

Biological Sex is Female vs. Male 1.06 (0.33-3.42) ns 0.77 (0.29-

2.91) nsKnown partner for ≥ 1 year vs. <1 year

1.10 (0.45-2.67) ns 0.60 (0.25-

1.41) ns

*GEE models with link logit, controlling for multiple partnershipsAOR=Adjusted Odds Ratio

ns= not significant

A higher proportion of recent high risk sharing behaviors occur within

female-male sex + injecting partnerships

Male-Male

Injec

ting Only Partn

ership

Female-M

ale Injecti

ng Only

Partnersh

ip

Female-M

ale Sexu

al + In

jecting P

artnersh

ip0%

5%

10%

15%

20%

25%

30%

Receptive Syringe Sharing

Partnership Type

Prev

alen

ce o

f rec

ent R

SS

Male-Male In

jecting O

nly Partnersh

ip

Female-M

ale Injecti

ng Only Partn

ership

Female-M

ale Sexu

al + In

jecting P

artnersh

ip0%

5%

10%

15%

20%

25%

30%

Receptive Cooker Use

Partnership Type

Prev

alen

ce o

f rec

ent R

CU

Overall p<0.01Overall p<0.01

Summary

• Sex-composition alone was not significantly associated with an increased odds of high risk sharing behaviors.

• Injecting partnerships engaged in sexual behaviors were at significantly greater odds of both receptive syringe sharing and receptive cooker use.

• For female-male injection partnerships, it appears to be the combination of a sexual and injecting partnership that drives high risk injection behaviors.

Future DirectionsFuture studies are needed to examine:

• Decision making processes within these injecting partnerships resulting in [or protecting from] high risk sharing behaviors.

• Why some partnerships remain HCV- even though they engage in high risk sharing behaviors with their HCV+ partners.

• Underlying factors influencing high risk sharing behaviors within sexual+injecting partnerships.

Acknowledgements to community collaborators and contributors

• Food Runners • HIV Prevention Project, SF AIDS Foundation• Homeless Youth Alliance• San Francisco Needle Exchange• SFDPH AIDS Office• SFDPH Adult Immunization Clinic• SFDPH Community Health Epidemiology & Disease

Control• SFDPH Housing and Urban Health• Street Outreach Services, SFCCC• Tenderloin Clinical Research Center (TCRC)

THANK YOU!

For more information:Email: MMorris@psg.ucsf.eduUFO study: www.ufostudy.org

InC3 Study: InC3.epi-ucsf.org