Sexual and emotional intimacy key to syringe sharing among women who inject drugs in Philadelphia

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Published in AIDS and Behavior, a recent study among women who inject drugs in Philadelphia set out to determine how the women’s relationships influenced syringe sharing. Women were more likely to use syringes after someone they had an intimate or close relationship with, including sex partners, people who helped them inject, and those providing emotional support.

Once on the decline, HIV diagnoses attributed to injection drug use have been rising in the US, and there are ongoing HIV outbreaks among people who inject drugs throughout the country. Changes in the drug supply and in drug using behaviours are contributing factors; synthetic opioids and mixtures of different drugs both lead to more frequent injections.

In Philadelphia, the proportion of new HIV diagnoses attributed to injection drug use increased by 151% between 2016 and 2019, alongside a 560% increase in fentanyl seized by law. Public health surveys among people who inject drugs in the city found that 89% of respondents reported injecting more than once a day, and 44% reported injecting more than four times a day. Less than a third reported using a new syringe for each injection; down from 44% in 2012.


harm reduction

Harm reduction is a set of practical strategies and ideas aimed at reducing negative consequences associated with drug use (including safer use, managed use and abstinence). It is also a movement for social justice built on a belief in, and respect for, the rights of people who use drugs.


Studies aim to give information that will be applicable to a large group of people (e.g. adults with diagnosed HIV in the UK). Because it is impractical to conduct a study with such a large group, only a sub-group (a sample) takes part in a study. This isn’t a problem as long as the characteristics of the sample are similar to those of the wider group (e.g. in terms of age, gender, CD4 count and years since diagnosis).


Improvement in a tumour. Also, a mathematical model that allows us to measure the degree to which one of more factors influence an outcome.


Short for logarithm, a scale of measurement often used when describing viral load. A one log change is a ten-fold change, such as from 100 to 10. A two-log change is a one hundred-fold change, such as from 1,000 to 10.


Receptive anal intercourse refers to the act of being penetrated during anal intercourse. The receptive partner is the ‘bottom’.

Dr Abby Rudolph and Susanna Rhodes from Temple University set out to determine how relationship factors influenced receptive syringe sharing – using a previously used syringe – among women who inject drugs in Philadelphia.

In 2020 they conducted interviews at Philadelphia’s largest syringe exchange. Eligible participants were adults who were assigned female at birth who reported injecting drugs daily with at least one other person in the previous six months. 

Participant characteristics

Sixty-four participants were included in the study. The median age was 37. Most participants identified as White (78%) and a quarter were of Hispanic ethnicity. Around 11% of the women reported that they were living with HIV, while 80% had a previous hepatitis C diagnosis.

The majority of participants (63%) reported income at or below $500 a month. Sixty-seven per cent of participants were unemployed, and 75% reported an illegal source of income, most often sex work or selling drugs.

Most participants (83%) reported being homeless in the previous six months, including all of the women who reported having a full or part time job. In the preceding two years, 59% of participants were incarcerated in a jail and 11% in a prison.

Drug use

Participants had been injecting drugs for a median of six years, the median number of daily injections was eight. Nearly all of participants reported injecting opioids: fentanyl (92%) and heroin (86%). Half reported injecting cocaine, nearly half (45%) methamphetamine, and nearly a quarter (22%) injected sedatives. Most (73%) participants had previously overdosed.

Researchers asked the participants about the people they injected drugs with, totaling 123 partners among the 64 participants. Over half of the women (56%) reported only one partner they had injected drugs with in the previous six months.

Most partners were male (62%) and were of similar age and ethnicity as the participants.  The median length of relationship was two years.

The women saw their injection partners frequently. They had daily interactions with 67% of partners, shared an injection setting with 55% of partners daily, and lived with (including in the same encampment) 56% of partners.

Over half (57%) of the injection partners were described as friends; less than a quarter (23%) of injection partners were also sex partners.  Participants were extremely likely to discuss personal and private matters with 41% of their partners and they received financial support from 37% of their partners.

Syringe sharing

Overall, women reported sharing a syringe after 21% of the partners they described.

Before adjusting for other factors, women who only had one injection partner were over three times more likely (prevalence ratio 3.27, 95%, CI: 1.45-7.40) to share syringes with that partner compared to women who had more than one injection partner. None of the women who had four or five injection partners used a syringe after any of their partners; nearly half of women with one partner (44%) shared syringes with their partner.

"Women's relationships influenced whether they used syringes after partners, with close relationships increasing the likelihood."

The researchers created two models using log-binomial regression in order to look at whether the nature of relationships influenced syringe sharing. They were unable to include race, age, ethnicity, and employment status in the final analysis because of convergence issues.  The following findings were significant in the final model(s).

After adjusting for other factors, women were nearly twice as likely to use a syringe after a partner who provided injection assistance (adjusted prevalence ratio [APR] = 1.92; 95%CI: 1.10–3.37); nearly three times as likely after a sex partner (APR = 2.77; 95%CI: 1.36–5.64); and over six times more likely after a partner who provided emotional support (APR = 6.19; 95%CI: 2.12–18.06).   

Women with more injection partners were less likely to use syringes after their partners (APR 0.66; 95%CI: 0.47–0.91).

The study had several limitations. The sample was largely White and the study was conducted at a syringe service programme, meaning participants were already seeking harm reduction services. People who inject drugs who do not access such services may be more likely to share syringes.


Using the median of eight injections per day found in this study, the researchers calculate that the supply of sterile syringes in Philadelphia is less than half of the estimated demand.

In this study, the relationships of women who inject drugs influenced whether they used syringes after partners, with close relationships increasing the likelihood. Women who only have one injection partner were particularly more likely to use a syringe after this partner.

The researchers urge for harm reduction efforts to be situated within the real world, social context of injection drug use. The authors call for women who inject drugs to be offered training on negotiating safer injection practices within the context of close relationships.