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. Author manuscript; available in PMC: 2021 Oct 15.
Published before final editing as: Int J Drug Policy. 2020 Apr 15;79:102756. doi: 10.1016/j.drugpo.2020.102756

THE EFFECT OF INJECTING ALONE ON THE USE OF DRUG CHECKING SERVICES AMONG PEOPLE WHO INJECT DRUGS

Karen McCrae a, Kanna Hayashi a,c, Geoff Bardwell a,b, Ekaterina Nosova a, MJ Milloy a,b, Evan Wood a,b, Lianping Ti a,b
PMCID: PMC7572842  NIHMSID: NIHMS1626533  PMID: 32304980

Abstract

Objectives

Drug checking services aim to provide people who use drugs with information on the content and purity of their substances as a harm reduction intervention. The objective of this study was to determine the relationship between injecting alone and use of drug checking services in Vancouver, Canada.

Methods

Data were derived from three prospective cohort studies of people who inject drugs (PWID). We conducted bivariable and multivariable logistic regression analysis to estimate the effect of injecting alone on use of drug checking services.

Results

Between May 2018 and December 2018, a total of 793 people who inject drugs were included in the study: 579 (73.0%) reported injecting alone and 177 (22.3%) reported use of drug checking services. In a multivariable model adjusted for various confounders (including various sociodemographic variables, drug use patterns, and whether participants had suffered physical attacks/violence), injecting alone was negatively associated with use of drug checking services (Adjusted Odds Ratio = 0.65; 95% Confidence Interval: 0.44–0.97).

Conclusions

We observed a negative association between injecting drugs alone and use of drug checking services, which may be due in part to a number of exogenous factors that prevent people who inject alone from accessing drug checking services (e.g., stigma, location of services). As these individuals are at heightened risk of experiencing overdoses, there is a need to pursue other strategies to reach this group of people who use drugs.

Keywords: drug checking, injecting alone, overdose

INTRODUCTION

In recent years, the number of deaths caused by opioid overdose has risen dramatically across North America. In 2018, approximately 68,500 people were estimated to have died of a drug overdose in the US (CDC 2019b, September 11) and 4,460 people died of apparent opioid-related overdoses in Canada (Special Advisory Committee on the Epidemic of Opioid Overdoses 2019). As of 2017 (the last year for which data is available), people died of apparent overdoses at the overall rate of 21.7 per 100,000 in the US (CDC 2019a), while individuals in the westernmost Canadian province of British Columbia (BC) suffered the highest illicit drug overdose death rate in the country at 30.4 per 100,000 population (Coroners Service 2019). This crisis is being overwhelmingly driven by the use of illicitly-manufactured synthetic opioids, particularly fentanyl, which has displaced the traditional heroin market (Beletsky and Davis, 2017b; Carlson, Nahhas, Martins and Daniulaityte, 2016a; Rudd, 2016). A wide array of interventions have been implemented in an attempt to mitigate this crisis, including the dissemination of naloxone kits (Hawk, Vaca & D'Onofrio, 2015), the opening of peer-run and hospital-based supervised injection (Kerr, Mitra, Kennedy & McNeil, 2017), and point-of-care drug checking services (Tupper, McCrae, Garber, Lysyshyn & Wood, 2018). Drug checking was originally implemented in recreational drug use settings in the United States in the 1960s and ‘70 s (Smith, 1974), with a second wave reaching Europe in the 1990s as synthetic party drugs such as 3,4-methylenedioxy-methamphetamine (MDMA) increased in popularity (Brunt et al., 2017). The primary rationale for the operation of drug checking for harm reduction purposes is to inform people who use drugs about the contents of their substances in order to enable them to make more informed decisions about their drug use.

While drug checking services in nightlife and music scenes have been studied elsewhere (Dilkes-Frayne, 2016; Measham, 2018), very little is known about the effectiveness of such services among people who inject drugs (PWID) (Bardwell & Kerr, 2018) – a group that experiences heightened societal risks, stigmas, and barriers to accessing health services (DeBeck et al., 2007). As drug checking has historically been designed for and marketed towards people who use drugs in nightlife and music scenes, it is reasonable to assume that barriers to accessing drug checking are higher for PWID than for this population, particularly in light of the risks and barriers to health and social services that this group typically experiences. While several studies suggest high willingness to use drug checking services among PWID (Kennedy et al., 2018; Krieger et al., 2018; Sherman et al., 2019), this does not appear to translate to use of drug checking services in many settings. For example, a recently published report from a health authority in London, Canada found that only 0.3% of visits to a local supervised consumption site (SCS) that hosted a pilot drug checking project led to a drug check (Middlesex-London Health Unit, 2019). This may have been due to a low willingness to access drug checking (those consuming drugs at SCS have a safer place to inject and may not deem it necessary to check their drugs before consuming therein), barriers to access, or a combination thereof (Bardwell, Boyd, Tupper & Kerr, 2019).

People who inject drugs alone are at particular risk of mortality and morbidity related to overdose as they typically consume substances in the absence of any public health interventions. Such individuals tend to be more vulnerable and experience heightened harms related to drug use (Mitra et al., 2019). For example, naloxone programs are unable to effectively reach such populations, as naloxone requires another person to administer it (Baca & Grant, 2005), and people who inject alone by definition use drugs under circumstances where overdoses are unlikely to be reversed. This has consequences for the risks involved in injecting drugs in the midst of an overdose crisis; in the Canadian context, the overwhelming majority of overdose deaths affect people who use drugs alone indoors (Coroners Service, 2019).

Drug checking has expanded dramatically in the city of Vancouver, Canada over the past several years through a series of drug checking projects undertaken by local organizations and health authorities. Fentanyl test strip testing has been made widely available within harm reduction centers, including overdose prevention sites (OPS) and supervised consumption sites (SCS) since 2017; more rigorous testing using Fourier Transform Infrared (FTIR) spectrometers have also been made available at select sites since November 2017 (Ministry of Mental Health & Addictions, 2017). Individuals who test substances at these sites are not required to consume the sample on site and are not required to dispose of the sample after testing, although they are able to do so if they choose to (Tupper et al., 2018). Individuals may also access other types of drug checking (e.g., reagent testing) offered privately or through non-profit service providers. Due to the widespread availability of drug checking and in light of the high risk of mortality among people who inject alone, this study examined the relationship between injecting alone and drug checking service utilization in Vancouver.

METHODS

Study design

Data were drawn from three prospective open cohort studies, namely the Vancouver Injection Drug Users Study (VIDUS), the AIDS Care Cohort to evaluate Exposure to Survival Services (ACCESS), and the At-Risk Youth Study (ARYS). Participants in these cohorts have been primarily recruited through self-referral, snowball sampling, and street outreach. While the cohorts have been described in detail elsewhere (Milloy et al., 2016; Strathdee et al., 1997; Wood, Stoltz, Montaner & Kerr, 2006), in brief: VIDUS is a cohort of adult, HIV-negative PWID; ACCESS is a cohort of adult, HIV-negative people who use drugs; and ARYS is a cohort of street-involved drug-using youth between the ages of 14 and 26. To be eligible for inclusion in the study, all individuals in the three cohorts must have used an illicit drug (not including cannabis, which was illegal for most of the study period) at least once, resided in the greater Vancouver region, and provided written informed consent in the month prior to enrollment.

At baseline and bi-annually, participants in VIDUS, ACCESS, and ARYS studies complete a harmonized and identical questionnaire administered by an experienced interviewer that span a wide array of questions including socio-demographic characteristics and drug use patterns. At each study visit, participants are provided with a $40 CDN stipend. VIDUS, ACCESS, and ARYS studies have been approved by the University of British Columbia/Providence Health Care Research Ethics Board.

Study sample

The present study is a cross-sectional study embedded within a prospective cohort study and was conducted between May 31, 2018 and December 1, 2018, as drug checking questions were added to the study instrument during this time period. The sample was restricted to participants who reported having injected drugs in the last six months.

Measures

The primary outcome of interest was having used drug checking services in the previous six months. The following question was asked: have you used any drug checking services in the last six months (yes vs. no). Use of drug checking services was not limited geographically nor was it limited to the type of test. Those who said yes to this question were then asked to describe the type of drug checking technology they had used. The primary explanatory variable of interest was whether participants had injected alone in the previous six months (yes vs. no).

Potential confounders that were considered were based on previous literature that suggested their likely impact (Hagan et al., 2007; Wood et al., 2001) and included sociodemographic variables such as: age (per year older); sex (male vs. female); self-reported ethnicity (white vs. non-white, i.e., Asian, Indigenous, Black, Other); whether the participant lived in unstable housing in the past six months (yes vs. no); whether the participant was in a stable relationship (i.e., had a regular partner) in the past six months (yes vs. no); whether the participant had completed high school (yes vs. no); and whether the participant had stable employment (i.e., regular job, temporary job, or self-employment) in the past six months (yes vs. no). A number of drug use patterns in the previous six months were also considered, including: whether the participant had injected in a supervised injection facility (yes vs. no); whether the participant had experienced a non-fatal overdose (yes vs. no); ≥ daily heroin injection (yes vs. no), ≥ daily cocaine injection (yes vs. no), ≥ daily methamphetamine injection (yes vs. no), ≥ daily illicit prescription opioid use (i.e., illicit use of prescription opioids such as OxyNEO, Percocet, Dilaudid, Vicodin, etc.) (yes vs. no), suspected exposure to fentanyl (yes vs. no), and whether participants had binged on injection drugs (i.e., whether participants had injected drugs more than usual in a “run” or “binge”) (yes vs. no). Whether participants had suffered physical attacks or violence in the previous six months (yes vs. no) was also considered, as such individuals may be more fearful of accessing the outside environment, including drug checking services, and have been demonstrated to be at heightened risk of accidental overdose (Braitstein et al., 2003).

Statistical analyses

First, we described the characteristics of the study sample, stratified by drug checking service utilization. Then, bivariable logistic regression analyses were conducted to determine factors associated with drug checking service utilization. Confounders significant in the bivariable analyses at p < 0.05 were then considered in a multivariable logistic regression model assessing the effect of injecting alone on drug checking service utilization. In a sensitivity analyses, we re-ran the multivariable logistic regression model using a p ≤ 0.10 cutoff for confounders. All data were analyzed using the R statistical software package, version 3.5.0 (R Foundation for Statistical Computing, Vienna, Austria). All p-values were two-sided and considered significant at p < 0.05.

RESULTS

A total of 793 people were eligible for inclusion during the study period (138 from ARYS, 422 from VIDUS, and 233 from ACCESS). Of these, 579 (73.0%) had injected alone and 177 (22.3%) had used drug checking services in the previous six months. Of the individuals who had used drug checking services, 56 had used fentanyl test strips, 57 had used FTIR spectroscopy, 47 had used both FTIR and fentanyl test strips, and 17 has used other types of other non-specified drug checking technologies. Among the 564 people who had reported using opioids in the previous six months, 84 (14.9%) preferred the use of fentanyl (data not shown). In total, the median age was 43.6 (Q1-Q3: 33.5–53.3) years and 303 (38.2%) were female. Among those who used drug checking services, we found that 605 (76.3%) suspected that they had been exposed to fentanyl in the previous six months. The full list of descriptive statistics is displayed in Table 1.

Table 1.

Descriptive statistics of the study sample, stratified by drug checking service use (n = 793).

Characteristic Total (%)
(n = 793)		 Outcome
Yes (%) No (%)
(n = 177) (n = 616)
Main exposure:
Injected alone* 579 (73) 119 (67.2) 460 (74.7)
Confounders:
Age (median, Q1-Q3) 43.6 (33.5–53.3) 41.1 (31–51.8) 44.1 (34.2–53.7)
Female sex 303 (38.2) 67 (37.9) 236 (38.3)
White ethnicity 363 (45.8) 90 (50.8) 273 (44.3)
Injected at a supervised injection facility* 451 (56.9) 143 (80.8) 308 (50)
Unstable housing* 557 (70.2) 132 (74.6) 425 (69)
In a stable relationship* 255 (32.2) 64 (36.2) 191 (31)
Completed less that high school education* 426 (53.7) 85 (48) 341 (55.4)
Stable employment* 183 (23.1) 40 (22.6) 143 (23.2)
Non-fatal overdose* 128 (16.1) 37 (20.9) 91 (14.8)
≥ Daily injection heroin use* 244 (30.8) 66 (37.3) 178 (28.9)
≥ Daily injection cocaine use* 32 (4) 1 (0.6) 31 (5)
≥ Daily injection meth use* 123 (15.5) 32 (18.1) 91 (14.8)
≥ Daily injection prescription opioid use* 12 (1.5) 3 (1.7) 9 (1.5)
Suspected exposure to fentanyl* 605 (76.3) 155 (87.6) 450 (73.1)
Binge use of injection drugs* 235 (29.6) 62 (35) 173 (28.1)
Physically attacked or suffered violence* 70 (8.8) 23 (13) 47 (7.6)
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*

Refers to the 6-month period before the interview.

The bivariable and multivariable analyses are displayed in Table 2. In bivariable analyses, injecting alone was negatively associated with drug checking service utilization (odds ratio [OR] = 0.70; 95% confidence interval [CI]: 0.49 – 1.00). As can be seen in the multivariable analysis adjusted for various confounders, injecting alone remained negatively associated with drug checking service utilization (adjusted OR = 0.65, 95% CI: 0.44–0.97). In sensitivity analyses, after adjusting for confounders p ≤ 0.1, we found that injecting alone had an adjusted OR of 0.63 (data not shown).

Table 2.

Factors associated with drug checking service utilization among people who inject drugs (n = 793).

Unadjusted
Odds Ratio
(95% CI)		 Unadjusted
P-Value		 Adjusted
Odds Ratio
(95% CI)		 Adjusted
P-Value
Main exposure:
Injected alone* (yes vs. no) 0.70 (0.49 - 1.00) 0.05 0.65 (0.44 - 0.97) 0.035
Confounders:
Age (per one-year increase) 0.99 (0.97 - 1.00) 0.045 1.00 (0.99 - 1.02) 0.867
Sex (male vs. female) 1.02 (0.72 - 1.44) 0.912 –
Ethnicity (white vs. others) 1.33 (0.95 - 1.87) 0.097 –
Injected at a supervised injection facility* (yes vs. no) 4.19 (2.83 - 6.38) <0.001 3.51 (2.31–5.44) <0.001
Unstable housing* (yes vs. no) 1.35 (0.93 - 1.99) 0.125 –
In a stable relationship* (legally married, common law, regular partner vs. others) 1.26 (0.88 - 1.78) 0.201 –
Education* (did not complete high school vs. completed high school or higher) 0.73 (0.52 - 1.02) 0.069 –
Stable employment* (yes vs. no) 0.96 (0.64 - 1.43) 0.856 –
Non-fatal overdose* (yes vs. no) 1.52 (0.98 - 2.30) 0.055 –
≥Daily injection heroin use* (yes vs. no) 1.46 (1.03 - 2.07) 0.034 1.13 (0.77 - 1.65) 0.537
≥Daily injection cocaine use* (yes vs. no) 0.11 (0.01 - 0.51) 0.028 0.13 (0.01 - 0.62) −2.065
≥Daily injection meth use* (yes vs. no) 1.27 (0.81 - 1.97) 0.285 –
≥Daily injection prescription opioid use* (yes vs. no) 1.16 (0.26 - 3.95) 0.822 –
Suspected exposure to fentanyl* (yes vs. no) 2.84 (1.69 – 5.10) <0.001 2.05 (1.16 - 3.81) 0.717
Binge use of injection drugs* (yes vs. no) 1.38 (0.96 - 1.96) 0.077 –
Physically attacked or suffered violence* (yes vs. no) 1.81 (1.05 - 3.04) 0.028 1.49 (0.83 - 2.61) 0.396
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CI: confidence interval.

*

Refers to the 6-month period before the interview.

DISCUSSION

In the present study, we observed that almost three-quarters of participants in the study injected drugs alone, while only a small proportion had used drug checking services. We also found a negative association between injecting drugs alone and using drug checking services, even after adjusting for various confounders. To our knowledge, this is the first quantitative cross-sectional study to document the relationship between injecting drugs alone and use of drug checking services.

These findings may be due in part to a number of plausible exogenous factors that prevent people who inject alone from accessing health and harm reduction services. Although more research into the social and structural conditions that influence using drugs alone is needed, existing research suggests that some people who use drugs inject alone due to an increased level of stigma and shame surrounding their drug use (Bardwell, Boyd, Kerr and McNeil, 2018). This may lead them to inject without the presence of others, even when they may acknowledge that doing so increases their personal health risks (Bardwell, Boyd, Kerr and McNeil, 2018). Studies further show that criminalization of drug use and targeted police action drives individuals to use privately indoors or in secluded areas away from the scrutiny of streetlevel enforcement (Small et al., 2006). All these factors may hinder their access to SCS, and in turn, they may be less likely to access the drug checking services located on the premises of these sites. Area restrictions may also contribute to the diminished likelihood of PWID accessing drug checking services and the increased likelihood of injecting alone. Commonly known as ‘red zone’ orders in Canada and ‘stay out of drugs areas,’ or ‘stay out of areas of prostitution’ orders in the United States, area restrictions prohibit people from entering designated drug or sex work areas or areas where they were arrested (McNeil, Cooper, Small & Kerr, 2015). Research shows that these restrictions function to disrupt access to health and social resources, displacing drugrelated activities to other, more dangerous locations and increasing vulnerability to harms such as unsafe drug use patterns (McNeil et al., 2015). In light of the fact that people who inject drugs are highly criminalized and that drug checking services in the region are located in SCS, which are themselves located in areas that commonly fall within red zones (Sylvestre, Blomley, Damon & Bellot, 2017), it is reasonable to hypothesize that the practice of area restricting is likely to increase barriers to accessing harm reduction services in these areas, including drug checking. More research is needed to determine whether geographical location plays a role in impacting the number of PWID who access drug checking services.

It is important to note that we are unable to infer causation as this study is cross-sectional in nature; while we expect that people who inject alone are less likely to access drug checking services due to a variety of structural barriers (Bardwell et al., 2019), it is also possible that people who use drug checking services are less likely to inject alone as a result of knowing the contents of their drug, or they may decide to use at the SCS since they are already present for the purposes of the drug check. However, consistent with previous literature, it seems more likely that the people who inject alone are less likely to use drug checking services due to the socialstructural barriers identified above. For example, a recent qualitative study in Vancouver found ambivalence to the use of drug checking services among structurally vulnerable PWID due to a variety of factors, including a stated disregard for the type of drugs used and lack of concern about risks associated with drug use, unwillingness to invest the time necessary to receive a drug check, and accessibility of drug checking services (Bardwell et al., 2019). Further research that seeks to tease apart the complex relationship between drug checking and injecting alone is needed to determine the chain of causation.

The findings from the present study reinforce the urgent need for novel policy strategies to be broadly implemented to address the opioid crisis. The current service model of drug checking available in Vancouver (i.e., operating out of SCS in the Downtown Eastside neighborhood of the city), which, according to the present study, does not seem to attract those who inject alone, is only one of many possible drug checking strategies. The introduction of various models such as those available in other settings globally, may increase uptake amongst more isolated populations.

For instance, many drug checking services targeting populations of people who use drugs in festival and recreational communities conduct pop-up, on-site operations at festival events, offices, hospitals, and outreach centers; others accept drug samples submitted through the postal service (Barratt, 2018). A limited pilot project began offering some access to take-home fentanyl test strips in the province beginning in May 2019, although these strips are available only from a tightly limited number of SCS and OPS (Interior Health Authority, 2019). While individuals who inject alone may be more willing to engage in drug checking if they are able to use strips at home, it should be emphasized that the strips must be acquired at these sites and a rigorous evaluation of the benefits of these programs have not yet been completed. However, the implementation of different service models may increase uptake of drug checking among underserved populations, including those who inject alone and are at heightened risk of overdose. Future evaluations should be conducted to determine whether these models are effective at reaching these populations.

Existing research has demonstrated that physical distances between harm reduction services and the residences and drug purchase and use locations of PWID have an impact on their willingness to access such services (Williams & Metzger, 2010). Evidence suggests that improving the convenience of harm reduction facilities also increases the uptake of such services (Hutchinson, Taylor, Goldberg & Gruer, 2000; Rockwell, Jarlais, Friedman, Perlis & Paone, 1999).

In light of this and the high proportion of overdose deaths that happen indoors (in BC in 2019, 87% of all overdose deaths occurred inside private residences, social and supportive housing, single room occupancy hotels, shelters, and hotels (Coroners Service, 2019), one possible drug checking service model should include outreach to housing facilities. As drug checking services in Vancouver (including take-home fentanyl strip tests and more advanced technologies) are largely limited to harm reduction centres, access to drug checking services is limited to those who are willing to travel to these sites. By decreasing barriers to accessing drug checking, housing-based service models may attract uptake from people who are not willing or able to travel to SCS or otherwise leave their residence.

Regardless of the model chosen, there is an urgent need for structural and policy changes that decriminalize and destigmatize drug use and encourage individuals to use drugs in safer environments where they can access a range of harm reduction services, including, but not limited to, drug checking. Importantly, even if the direction of causality that we hypothesize is incorrect and people who use drug checking services are less likely to inject alone as a result of their drug check, injecting alone remains associated with increased vulnerabilities and health risks. The fact that almost three-quarters of participants in the study inject alone (73.0%) is of concern and underscores the critical importance of harm reduction services, decriminalization, and destigmatization of drug use to increase the safety of this subpopulation. In particular, safe supply initiatives would obviate the need for drug checking, which is only necessary in the context of the unregulated drug market. If individuals had access to a regulated and safe supply of drugs, drug composition would not need to be checked by private and nongovernmental actors.

The present study has several additional limitations that should be noted. Our findings may not be generalizable to other settings and the study sample may not be representative of other populations of PWID. Moreover, this study relied on self-reported data and participant responses may be subject to reporting bias. Finally, although the study controlled for a number of possible confounding factors, there is the possibility that the observed negative association between accessing drug checking services and injecting alone may be explained by residual confounding.

CONCLUSION

In conclusion, our study found that people who inject alone are less likely to access drug checking services. This subgroup of individuals may be distinctly at risk of overdosing in the midst of an unequaled public health emergency. This finding underscores the urgency of implementing novel strategies, including expanded access to a variety of drug checking models and structural policy changes that destigmatize and decriminalize drug use.

Highlights.

  • We conducted logistic regression analysis to estimate the effect of injecting alone on use of drug checking services.

  • People who inject alone are less likely to use drug checking services.

  • Other strategies must be pursued to reach this group of people.

Acknowledgments

The authors thank the study participants for their contribution to the research, as well as current and past researchers and staff. The study was supported by the US National Institutes of Health (U01DA038886; U01DA021525) and the Canadian Institutes of Health Research (CIHR) Canadian Research Initiative on Substance Misuse (SMN–139148). M-JM is supported by NIDA (U01DA021525), and CIHR New Investigator and MSFHR Scholar Awards. He is the Canopy Growth professor of cannabis science at the University of British Columbia, a position established through arms’ length gifts to the university from Canopy Growth, a licensed producer of cannabis, and the Government of British Columbia's Ministry of Mental Health and Addictions. GB is supported by a CIHR postdoctoral fellowship. EW is supported by a Tier 1 Canada Research Chair in Addiction Medicine. LT is supported by a MSFHR Scholar Award. KH is supported by a CIHR New Investigator Award (MSH-141971), a Michael Smith Foundation for Health Research (MSFHR) Scholar Award, and the St. Paul's Foundation.

Footnotes

Declaration of Competing Interest

None.

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