Table 2 Summary of main research findings of studies included in review

Hagan et al. 2000 [19]^a

Cooker or Filter

NSP users vs. nonusers

AOR (95%CI) of sharing paraphernalia with adjustment for heroin injection, frequency of injection, and syringe or cooker/cotton sharing or back loading

0.79 (0.58 - 1.08)

Huo et al. 2007 [20]^a

Cooker, Filter or rinse water

NSP users vs. nonusers

Proportion of participants reporting sharing paraphernalia (behaviour at baseline to behaviour at 3 year follow up)

NSP users: 60% to ~22%

NSP nonusers: 70% to ~22%

Huo et al. 2007 [20]^a

Cooker, Filter or rinse water

NSP users vs. nonusers

AOR (95%CI) of sharing paraphernalia with adjustment for year recruited, age, race, heroin or cocaine injection, injecting with others at least half the time, injecting in semi-public settings, injecting in shooting gallery, and having an IDU sex partner

0.70 (0.52 - 0.95)

Sears et al. 2001 [21]^a

Cooker, Filter or rinse water

NSP users vs. nonusers

(complete case analysis, n = 101)

Proportion of participants reporting sharing paraphernalia (behaviour at baseline to behaviour at 1 year follow up)

NSP users: 61% to 45%

NSP nonusers: 40% to 30%

Stoltz et al. 2007. [22]^a

Water

Frequent SIF user vs. infrequent SIF user

AOR (95%CI) of using clean water for injecting with adjustment for age, gender, sex trade involvement, daily cocaine and heroin injection

2.99 (2.13 - 4.18)

Vlahov et al. 1997 [23]^a

Cooker

Pre- vs. post-enrolment in NSP

Proportion of participants reporting sharing paraphernalia

(at baseline and at 6 months)

59% to 39% ^d

Vlahov et al. 1997 [23]^a

Filter

Pre- vs. post-enrolment in NSP

Proportion of participants reporting sharing paraphernalia

(at baseline and at 6 months)

46% to 31% ^d

Bluthenthal et al. 1998 [24]

Cooker, Filter or rinse water

Temporal trends in prevalence of sharing paraphernalia

Proportion of participants reporting sharing paraphernalia between wave 1 (1992) and wave 7 (1995)

~62% to ~40% ^d

Bluthenthal et al. 1998 [24]

Cooker, Filter or rinse water

Receipt of sterile injecting

paraphernalia in last 30 days vs. not

AOR (95%CI) of sharing paraphernalia with adjustment for wave of study recruitment, gender, neighbourhood, homelessness, HIV status, race, age, frequency of injection and drug preference.

1.11 (0.89 - 1.39)

Bluthenthal et al. 1998 [24]

Cooker, Filter or rinse water

NSP users vs. nonusers

AOR (95%CI) of sharing paraphernalia with adjustment for wave of study recruitment, gender, neighbourhood, homelessness, HIV status, race, age, frequency of injection and drug preference.

0.85 (0.68 - 1.07)

Morissette et al. 2009 [25]

Cooker

Use of sterile injecting equipment 'half the time or more' vs. 'less than half the time' in the last month

OR (95%CI) of sharing drug preparation equipment in the last 6 months

0.42 (0.22 - 0.80)

Morissette et al. 2009 [25]

Filter

Use of sterile injecting equipment 'half the time or more' vs. 'less than half the time' in the last month

OR (95%CI) of sharing drug preparation equipment in the last 6 months

0.52 (0.28 - 0.97)

Morissette et al. 2009 [25]

Water

Use of sterile injecting equipment 'half the time or more' vs. 'less than half the time' in the last month

OR (95%CI) of sharing drug preparation equipment in the last 6 months

0.51 (0.29 - 0.90)

Morissette et al. 2009 [25]

Cooker

Use of sterile injecting equipment 'half the time or more' vs. 'less than half the time' in the last month

AOR (95%CI) of being HCV negative vs. HCV positive (self-reported) adjusted for age, gender, education, injecting heroin as a primary drug, daily injecting, injecting alone, requiring help with injecting and problems obtaining sterile equipment from a NSP

3.92 (1.58 - 9.70)

Morissette et al. 2009 [25]

Filter

Use of sterile injecting equipment 'half the time or more' vs. 'less than half the time' in the last month

AOR (95%CI) of being HCV negative vs. HCV positive (self-reported) adjusted for age, gender, education, injecting heroin as a primary drug, daily injecting, injecting alone, requiring help with injecting and problems obtaining sterile equipment from a NSP

No association ^g

Morissette et al. 2009 [25]

Water

Use of sterile injecting equipment 'half the time or more' vs. 'less than half the time' in the last month

AOR (95%CI) of being HCV negative vs. HCV positive (self-reported) adjusted for age, gender, education, injecting heroin as a primary drug, daily injecting, injecting alone, requiring help with injecting and problems obtaining sterile equipment from a NSP

2.93 (1.12 - 7.68)

Longshore et al. 2001^e [26]

Cooker

NSP attendance > 4 times vs. once or less/month

AOR (95%CI) of sharing paraphernalia with adjustment for age, race, sex, injection frequency, primary drug, and treatment experience.

0.39 (0.16 - 0.95)^c

Longshore et al. 2001^e [26]

Cooker

NSP attendance > 4 times vs. 2-4 times/month

AOR (95%CI) of sharing paraphernalia with adjustment for age, race, sex, injection frequency, primary drug, and treatment experience.

0.50 (0.28 - 0.89) ^c

Longshore et al. 2001^e [26]

Filter

NSP attendance > 4 times vs. once or less/month

AOR (95%CI) of sharing paraphernalia with adjustment for age, race, sex, injection frequency, primary drug, and treatment experience.

0.64 (0.27 - 1.52)

Longshore et al. 2001^e [26]

Filter

NSP attendance > 4 times vs. 2-4 times/month

AOR (95%CI) of sharing paraphernalia with adjustment for age, race, sex, injection frequency, primary drug, and treatment experience.

0.88 (0.49 - 1.59)

Kipke et al. 1997 [27]

Cooker, Filter or rinse water

NSP users vs. nonusers

AOR (95%CI) of sharing paraphernalia with adjustment for age, gender and ethnicity

0.53 (0.28 - 0.99)^c

Sears et al. 2001 [28]

Filter

Intervention site vs. comparison site^f

AOR (95%CI) of using someone else's cotton with adjustment for age, race/ethnicity, illegal/marginal income source, use of drop-in centre, and number of times consumed alcohol in the past 30 days

No association ^g

Heimer et al. 2002. [29]

Cooker

NSP users vs. nonusers

Proportion of participants reporting sharing paraphernalia in last 30 days

9% vs.12% ^b

Heimer et al. 2002. [29]

Filter

NSP users vs. nonusers

Proportion of participants reporting sharing paraphernalia in last 30 days

6% vs.8% ^b

Heimer et al. 2002. [29]

Rinse water

NSP users vs. nonusers

Proportion of participants reporting sharing paraphernalia in last 30 days

3% vs. 9% ^d

Heimer et al. 2002. [29]

Drug water

NSP users vs. nonusers

Proportion of participants reporting sharing paraphernalia in last 30 days

3% vs.9% ^c

Guydish et al. 2008 [30]

Cooker, Filter or rinse water

NSP users who reported sharing rinse water in preceding 30 days vs. those who did not

Mean NSP visits in past 30 days

4.36 vs. 3.75 ^b

Guydish et al. 2008 [30]

Cooker, Filter or rinse water

NSP users who reported sharing rinse water in preceding 30 days vs. those who did not

Mean percent of syringes obtained from NSP

86% vs. 89% ^c

Colon et al. 2009 [31]

Water bottle

Pre vs. post intervention (18 week follow up)

Percentage of participants adopting injecting practices in the preceding 7 days

0% vs 56%^d,h

Colon et al. 2009 [31]

Syringe filter

Pre vs. post intervention (18 week follow up)

Percentage of participants adopting injecting practices in the preceding 7 days

0% vs. 34%^c,h

Colon et al. 2009 [31]

Cooker

Pre vs. post intervention (18 week follow up)

Percentage sharing cooker during last day of injection

16% vs. 6% ^b