Transition from injecting opioids to smoking fentanyl in San Francisco, California
Introduction
There are an estimated six million people who have injected drugs (PWID) in the United States (Bradley et al., 2020; Lansky et al., 2014; Tempalski et al., 2013) and 15.6 million PWID globally (Degenhardt et al., 2017). Injection drug use is associated with transmission of blood borne infectious diseases such as HIV (Des Jarlais et al., 1985, 2020) and viral hepatitis (Girardi et al., 1990; Rashti et al., 2020; Sharhani et al., 2021), as well as abscesses and other soft tissue infections (Binswanger et al., 2000; See et al., 2020), and infective endocarditis (Kadri et al., 2019). Reducing the number of people who inject drugs and the number of times people inject drugs are public health goals, given the health complications associated with injection drug use. Public health campaigns in Scotland, Spain, and Australia in the 1990s aimed to convince PWID to switch to non-injectable routes of administration (Bridge, 2010; Dolan et al., 2004; Wodak, 1997). One study in Germany in 2012 showed it was possible to have people switch to smoking if safe consumption sites provided free sterile aluminum foil (Stover and Schaffer, 2014). However, these recommendations have been difficult for people to heed, as there are many reasons why people inject their drugs as opposed to other modes of administration.
Modes of administering drugs have long been dependent on the motivations for using drugs, types of drugs used, and drug market availability (Harris et al., 2015; Syvertsen et al., 2016) and cost (Swift et al., 1999). For most substances, bioavailability is highest when injected, making injection the most economical choice, an important factor when drugs are scarce or expensive relative to income. Others value the fast onset of injected drugs, which can be particularly important in situations where people are in drug withdrawal (Bluthenthal et al., 2020; Valente et al., 2020). The type of drug solution can also dictate modes of administration. For example, for many decades, heroin in the Western United States has consisted of a tar-like substance that is hard to administer in any way other than injection (Ciccarone, 2009; Roth et al., 2017).
The frequency with which people inject drugs can also be dependent upon the types of drugs they use. For example, people who inject cocaine tend to inject more times per day than people who inject methamphetamine or heroin (Ciccarone and Bourgois, 2016; Hyshka et al., 2012). People who use fentanyl appear to use it more frequently than people who use heroin because it has a shorter duration of action (Buresh et al., 2019; Geddes et al., 2018; Kim et al., 2020; Lambdin et al., 2019; Zibbell et al., 2021). The types of drugs used also confer risk for infectious diseases, overdoses, and soft tissue infections (Hyshka et al., 2012; Ivsins et al., 2020; Lambdin et al., 2019; Rhodes et al., 2007).
Given that types of drugs can dictate modes and frequency of administration, shifts in drug markets can be an important contributing factor to the prevalence of injection. The transition from smoking opium to injecting heroin in southeast Asia in the 1970s was driven by policing practice and price changes (Westermeyer, 1976). The shift in the drug market from powder cocaine to crack cocaine reduced drug injection significantly in the United Kingdom and Spain in the 1990s (Barrio et al., 1998; Hunter et al., 1995), and Montreal, Canada in the early 2010s (Roy et al., 2012). In the US in the 2010s, the tightening regulation of opiate pills led to a surge in heroin use, which increased the number of PWID (McCabe et al., 2020).
With the US illicit opioid market having made a momentous shift towards illicitly made fentanyl in the mid-2010s, there have been devastating increases in related overdose mortality (Mattson et al., 2021). We reported recently that fentanyl use was increasing among PWID in Los Angeles and San Francisco and found that nonfatal overdose increased among those using fentanyl (Lambdin et al., 2019). During this period, San Francisco California has had a 270 percent increase in opioid-related overdose mortality from 2018 to 2020 (259 opioid overdose fatalities in 2018, 442 in 2019, and 699 in 2020) (Thadani, 2021). The proportion of overdose deaths that involved fentanyl in San Francisco increased from 16 % in 2017 to 34 % in 2018, 54 % in 2019, and 72 % in 2020 (Rodda, 2021). It is important to learn whether these recent changes in the drug market have impacted the mode of administration, including injection. We conducted a mixed methods observational study to assess changes in the prevalence of injections and smoking of fentanyl among PWID in the context of growing fentanyl availability during 2018–2020.
Section snippets
Methods
Data analyzed in this study were collected using an exploratory sequential mixed method study design, which included quantitative and qualitative community-based methods. Using targeted sampling, we recruited 395 PWID in San Francisco, California (Kral et al., 2010; Watters and Biernacki, 1989). Participants completed quantitative interviews at baseline, 6 and 12 months from 2018 to 2020. Qualitative data collection (N = 21) took place before, during, and following quantitative data collection
Quantitative findings
There were 395 participants enrolled. Retention in the study was 81 % (n = 322) at 6-months (January 2019 to February 2020) and 77 % (n = 305) at 12-months (July 2019 to June 2020). The sample consisted of a quarter cis-women, 19 % African American, 14 % Latinx, the vast majority considered themselves to be homeless (86 %), and the median age was 39 years old (interquartile range (IQR) 32–50, Table 1). Almost all (88 %) had injected opioids at least once in the 30 days prior to enrollment. The
Discussion
Our quantitative results suggest the number of injections has been decreasing precipitously among PWID in San Francisco from 2018 to 2020. During the same period, we found that among PWID who use fentanyl, the number of days they smoke fentanyl has increased. We received data on the number of syringes provided by the largest syringe services program in San Francisco during our study period. They provided fewer syringes in January to June 2020 (n = 1,479,976) than in the previous three
Role of funding source
This research was funded by Arnold Ventures and United States National Institute on Drug Abuse, neither of which had any role in study design, data collection, analysis and interpretation of data, the writing of the report or the decision to submit the article for publication.
Contributors
All authors contributed to conceptualization, analysis, writing and editing.
Declaration of Competing Interest
No author has any conflicts to declare
Acknowledgments
This work was supported by Arnold Ventures and the United States National Institute on Drug Abuse grants R01DA046444 and R01DA046049.
We would like to thank the following people for important contributions: Finn Black, Veronica Majano, Terry Morris, and Rachel Robinson. We would like to thank the following ethnographers, drug use researchers and syringe service providers for providing us context in December 2020 on whether smoking is a predominant mode of administrating fentanyl in their cities:
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