1. 22 November 2018
Factors predicting usage of low dead space syringes and association with Hepatitis C prevalence amongst people who inject drugs in the UK
Adam Trickey1,2, Margaret T May1,2, Vivian Hope3,4, Zoe Ward1,2, Monica Desai4, Ellen Heinsbroek4, Matthew Hickman1,2, Peter Vickerman1,2
1Bristol Medical School, University of Bristol 2NIHR Health Protection Research Unit (HPRU) for the Evaluation of Interventions 3Liverpool John Moores University 4Public Health England

2. People who inject drugs (PWID) and hepatitis C virus (HCV)
22 November 2018
People who inject drugs (PWID) and hepatitis C virus (HCV)
People who inject drugs (PWID) are at risk of blood borne viral infections through the sharing of needles, syringes, and other injecting equipment1
There is high prevalence of these infections, such as hepatitis C virus (HCV), amongst PWID1
Needle and syringe programmes and opiate substitution therapy can decrease the risk of getting HCV2
However, modelling suggests they are not enough to reduce HCV to low levels2
So other prevention or treatment strategies are required
-Mention cochrane review (platt & hickman)
1: Degenhardt, : Platt, 2017

3. Low dead space syringes (LDSS)
22 November 2018
Low dead space syringes (LDSS)
Syringes with attached needles, typically have a lower ‘dead space’ and retain far less blood following an injection, than syringes with detachable needles1
Fixed needle (1ml)
Low dead space syringes (LDSS)
Detachable needle
High dead space syringes (HDSS)
1: Zule, 2013

4. Low dead space syringes (LDSS)
22 November 2018
Low dead space syringes (LDSS)
For PWID that share injecting equipment, using low dead space syringes (LDSS) instead of high dead space syringes (HDSS) may lead to a reduced risk of acquiring blood borne infections1
The volume of blood held in a syringe predicts:
The amount of viral load transmitted2
Virus survival outside of the body2
The World Health Organization (WHO) recommends that LDSS are supplied to prevent the transmission of blood borne viruses
However, evidence for a prevention benefit is limited3
1: Vickerman, 2013, 2: Gaughwin, : Jacka, 2013

5. Research into which subgroups of PWID use LDSS has been limited
22 November 2018
Research into which subgroups of PWID use LDSS has been limited
Some research indicates HDSS with longer needles are required for injecting into veins around the groin1
HDSS allow replacement of needles during an injection episode1
Injecting practices differ depending on the drug2
Some older PWID inject into their groin after veins in the limbs are worn out3
Previous research indicates that groin injectors are more likely to have high risk behaviours3
Some crack users prefer wider needles – “bitty”
1: Zule, 2013, 2: Lankenau, 2004, 3: Hope, 2015

6. 22 November 2018
Aims
To investigate the predictors of LDSS use amongst PWID to gain information about how to intervene
To examine whether the type of syringe used is associated with reduced risk of HCV in the UK

7. Dataset 2014 and 2015 Unlinked Anonymous Monitoring Survey (UAM)
22 November 2018
Dataset
2014 and 2015 Unlinked Anonymous Monitoring Survey (UAM)
Annual sero-behavioural survey of PWID
Recruited from centres providing drug treatment, needle and syringe programmes and outreach work
Data from across England, Wales, and Northern Ireland (not Scotland)
Participants answer questionnaire about their drug use behaviours and demographic information
Participants provide a dried blood spot sample that was tested for HCV antibodies.

8. 22 November 2018
LDSS data
We calculated the percentage of syringes used in the past month that were LDSS or HDSS
Used two questions based on self-report:
“How many individual needles (including ones attached to syringes) did you get from Needle Exchanges during the last month (28 days)?”
“How many of these needles were already attached to syringes (barrels)?”
We excluded participants without information on LDSS use.
We used multiple imputation to account for missing data in covariates.

9. 22 November 2018
Methods
To investigate which subgroups of PWID used LDSS all the time, we used:
Logistic regression to estimate unadjusted odds ratios (OR) with 95% confidence intervals (CI) of 100% LDSS usage, vs 0-99% use, with demographic and injecting variables.
Multivariable logistic regression with backwards selection of predictors.
To investigate the relationship between LDSS use and HCV infection risk:
We estimated associations of LDSS usage with HCV with and without adjusting for groin injecting – due to the correlation between HDSS use and groin injecting
Using multivariable logistic regression
We repeated this with an interaction term between LDSS use and groin injecting
We repeated this analysis including an interaction term between LDSS use and whether a PWID recently started injecting (less than 3 years ago) – as many prevalent HCV infections will have occurred many years ago

10. Results – Demographics and characteristics
22 November 2018
Results – Demographics and characteristics
3,083 had injected in the previous month
-> 909 (28%) excluded due to missing information on LDSS use
-> 2,174 included in the analyses
-> 55% always used LDSS
-> 17% used both LDSS and HDSS
-> 27% always used HDSS.
Variable
Total
Number
2,174
Age (years) - Mean 37
Days injecting last month – Mean 17
Injecting duration (years) - Mean 15
Women
24%
anti-HCV positive 
55%
Ever been in prison
70%
Homeless in last year
19%
Shared equipment last month
37%
Injected into groin last month
40%
Injected heroin last month
90%
Injected crack last month
43%
Injected cocaine last month 8%
Injected speed last month
21%

11. Predictors of LDSS usage
22 November 2018
Predictors of LDSS usage
Those injecting into the groin were very unlikely to use LDSS compared to those not injecting into the groin, aOR 0.14 ( )
Injecting crack was predictive of not using LDSS, aOR 0.79 ( )
Heroin injectors were more likely to use LDSS than non-heroin injectors, aOR 1.47 ( )
-those using what were classified as “other” drugs within the survey were also less likely to use LDSS all the time

12. Regional variation Highest: West Midlands (68%) Second: London (66%)
22 November 2018
Regional variation
Highest: West Midlands (68%)
Second: London (66%)
Lowest: East Midlands (45%)

13. LDSS usage and HCV 22 November 2018
Proportion of PWID with HCV, stratified by injecting duration and whether or not they always used LDSS
Dark grey bars are those that use low dead space syringes all the time
Light grey bars are those that don’t
Prevalence of HCV increases with injecting duration

14. Fully adjusted without groin injecting
22 November 2018
Odds ratios (OR) of being anti-HCV positive (against negative) N=2,174.
Variable
Unadjusted
Fully adjusted without groin injecting
Fully adjusted
0-99% LDSS use 1
100% LDSS use
0.64 (0.54, 0.76)
0.77 (0.64, 0.93)
0.95 (0.77, 1.18)
Injections (every 10) per month
1.11 (0.92, 1.33)
1.10 (0.90, 1.35)
1.07 (0.87, 1.31)
Shared equipment last month
1.22 (1.01, 1.46)
1.27 (1.04, 1.55)
1.30 (1.06, 1.59)
Injecting duration
1.08 (1.07, 1.09)
1.07 (1.06, 1.08)
Injecting crack
2.58 (2.15, 3.09)
2.23 (1.83, 2.71)
2.17 (1.78, 2.65)
Injecting heroin
1.67 (1.24, 2.24)
1.20 (0.86, 1.68)
1.15 (0.82, 1.61)
Injecting “other drug”
0.77 (0.54, 1.11)
0.78 (0.52, 1.17)
0.81 (0.54, 1.21)
Injecting into groin
2.35 (1.96, 2.81) NA
1.67 (1.35, 2.08)
Ever been in prison
2.83 (2.34, 3.42)
2.10 (1.71, 2.58)
2.04 (1.66, 2.51)
Homeless in last year
1.18 (0.95, 1.47)
1.23 (0.96, 1.57)
1.20 (0.94, 1.53)
-first column is the unadjusted analyses looking at the relationship between the variables and HCV
-exclusive LDSS use associated with lower odds of hep c
-when adjusted for other variables such as drug type and injecting duration (second column) LDSS use still associated with lower odds of HCV
-however when also adjusting for groin injecting there is no association between ldss use and hcv
-groin injecting is associated with higher odds of HCV
-mention separate analysis looking at non groin injectors
Also: The aOR of HCV infection for exclusive LDSS use (versus any HDSS use) amongst non-groin injectors was 0.86 (0.65, 1.13).

15. LDSS usage and HCV amongst PWID that had recently started injecting
22 November 2018
LDSS usage and HCV amongst PWID that had recently started injecting
Variable
Unadjusted
Fully adjusted without groin injecting
Fully adjusted
0-99% LDSS use & recent starter 1
100% LDSS use & recent starter
0.46 (0.26, 0.80)
0.53 (0.30, 0.95)
0.60 (0.34, 1.08)
Injections (every 10) per month
1.11 (0.92, 1.33)
1.10 (0.90, 1.35)
1.07 (0.87, 1.31)
Shared equipment last month
1.22 (1.01, 1.46)
1.29 (1.05, 1.57)
1.31 (1.07, 1.61)
Injecting duration
1.08 (1.07, 1.09)
1.06 (1.05, 1.08)
1.06 (1.05, 1.07)
Injecting crack
2.58 (2.15, 3.09)
2.26 (1.85, 2.76)
2.20 (1.81, 2.69)
Injecting heroin
1.67 (1.24, 2.24)
1.18 (0.84, 1.65)
1.13 (0.81, 1.58)
Injecting “other drug”
0.77 (0.54, 1.11)
0.78 (0.52, 1.17)
0.81 (0.54, 1.22)
Injecting into groin
2.35 (1.96, 2.81) NA
1.66 (1.34, 2.06)
Ever been in prison
2.83 (2.34, 3.42)
2.06 (1.68, 2.53)
2.00 (1.63, 2.47)
Homeless in last year
1.18 (0.95, 1.47)
1.23 (0.97, 1.58)
1.21 (0.94, 1.54)
-within last 3 years
-this analysis was performed as a lot of the hcv infections are probably historical and by restricting the analysis to this subset there is more chance of the behaviours at the time of hcv infection being captured in the survey
-same as last table, but there is stronger evidence of reduced odss of hcv for ldss users
-groin injecting is still associated with higher odds of hcv

16. 22 November 2018
Limitations
Hard to separate out effects of LDSS use and groin injecting
98% responded to the groin injecting question, but only 72% to the LDSS questions
We could only examine injecting practices in the past month
We were unable to determine how current injecting practices related to practice over time
Do not know when participants had been infected with HCV, could have been many years ago
Recall bias and social desirability considerations
Some detachable needles are now low dead space, but this availability was unlikely during the study period
-(social desirability) we have a variable, self-reported, on sharing equipment but this is not necessarily reliable. Andrew mcauley did a talk where he mentioned that when questioned about whether or not they shared needles most PWID would say they didn’t but then when asked to describe their last injection it turns out that they are sharing equipment
-we are still debating whether the method of adjusting for groin injecting that we used is correct or whether we should use a mediation analysis, but either way the results seem to be the same that the use of syringe type does not explain many of the excess hepatitis c infections caused by groin injecting

17. 22 November 2018
Main results
Around 2/3 of our sample used LDSS every time they injected in the past month.
1/4 were not using LDSS.
Geographic differences in LDSS use across the UK, possibly due to variation in provision of LDSS, and variation in the types of drugs injected
Our study found an unadjusted association between LDSS use and HCV infection.
Association maintained following adjustment for drug type and injecting duration
These associations weakened following adjustment for injecting into the groin, which was highly correlated with HDSS use

18. 22 November 2018
Implications
To determine whether LDSS use reduces HCV infection risk it is crucial to understand the relationship with groin injecting
We know more about who uses LDSS in the UK
Groin injectors are a distinct subset of PWID who use HDSS with longer needles to enable injection into deep lying veins
For WHO guidelines to work needles are required that meet the needs of all PWID and minimise dead space
Detachable syringes with lower dead space are being developed but they still have greater dead space than LDSS
The association amongst recent initiates suggests LDSS may reduce HCV infection risk but more evidence is needed to confirm this

19. 22 November 2018
Acknowledgements
No conflicts of interest.