Aims Most people who inject drugs (PWID) were first initiated into injection by a current PWID. Few studies have examined PWID who assist others into drug injection. Our goal is to describe the prevalence of and risk factors for initiating someone into injection in the last 12 months. Methods We recruited a cross-sectional sample of PWID (N=605) in California from 2011 to 2013. We examined bivariate and multivariate risk factors for initiating someone into injection with a focus on behaviors that might encourage injection initiation such as injecting in front of non-PWID, describing how to inject to non-PWID, and willingness to initiate someone into drug injection. Results Having initiated someone into injection was reported by 34% of PWID overall and 7% in the last 12 months. Forty-four PWID had assisted 431 people into injection in the past year. Factors independently associated with initiating someone into injection in the last 12 months were having injected any person in past month – referred to as being a street doctor‟ -- (Adjusted Odds Ratio [AOR]=3.49; 95% confidence interval [CI]=1.72, 7.08), having described how to inject to non-injectors (2.76; 95% CI=1.28, 5.93), self-reported likelihood of initiating someone in the future (AOR=6.37; 95% CI=3.12, 13.01), and non-injection powder cocaine use in past month (AOR=4.40; 95% CI= 1.90, 10.19). Conclusion Active PWID are important in facilitating the process of drug injection uptake. Interventions to reduce initiation should include efforts to change behaviors and intentions among PWID that are associated with injection uptake among others.

Background Ecological momentary assessment (EMA) uses mobile technology to enable in situ self-report data collection on behaviors and states. In a typical EMA study, participants are prompted several times a day to answer sets of multiple-choice questions. Although the repeated nature of EMA reduces recall bias, it may induce participation burden. There is a need to explore complementary approaches to collecting in situ self-report data that are less burdensome yet provide comprehensive information on an individual’s behaviors and states. A new approach, microinteraction EMA (μEMA), restricts EMA items to single, cognitively simple questions answered on a smartwatch with single-tap assessments using a quick, glanceable microinteraction. However, the viability of using μEMA to capture behaviors and states in a large-scale longitudinal study has not yet been demonstrated. Objective This paper describes the μEMA protocol currently used in the Temporal Influences on Movement & Exercise (TIME) Study conducted with young adults, the interface of the μEMA app used to gather self-report responses on a smartwatch, qualitative feedback from participants after a pilot study of the μEMA app, changes made to the main TIME Study μEMA protocol and app based on the pilot feedback, and preliminary μEMA results from a subset of active participants in the TIME Study. Methods The TIME Study involves data collection on behaviors and states from 246 individuals; measurements include passive sensing from a smartwatch and smartphone and intensive smartphone-based hourly EMA, with 4-day EMA bursts every 2 weeks. Every day, participants also answer a nightly EMA survey. On non–EMA burst days, participants answer μEMA questions on the smartwatch, assessing momentary states such as physical activity, sedentary behavior, and affect. At the end of the study, participants describe their experience with EMA and μEMA in a semistructured interview. A pilot study was used to test and refine the μEMA protocol before the main study. Results Changes made to the μEMA study protocol based on pilot feedback included adjusting the single-question selection method and smartwatch vibrotactile prompting. We also added sensor-triggered questions for physical activity and sedentary behavior. As of June 2021, a total of 81 participants had completed at least 6 months of data collection in the main study. For 662,397 μEMA questions delivered, the compliance rate was 67.6% (SD 24.4%) and the completion rate was 79% (SD 22.2%). Conclusions The TIME Study provides opportunities to explore a novel approach for collecting temporally dense intensive longitudinal self-report data in a sustainable manner. Data suggest that μEMA may be valuable for understanding behaviors and states at the individual level, thus possibly supporting future longitudinal interventions that require within-day, temporally dense self-report data as people go about their lives.

BACKGROUND Studies report that among people who inject drugs (PWID), approximately 1 in 7 initiated injection during their thirties or later (referred to hereafter as “late initiates”). However, little is known about individuals who are late initiates. This study aims to describe characteristics of late initiates to drug injection and to examine how they differ from people who initiated drug injection prior to the age of 30 (“typical initiates”). METHODS We recruited 696 active PWID in Los Angeles and San Francisco, California between 2011 and 2013, using targeted sampling and street outreach methods. Participants completed personal interviews that covered items on demographics, drug use history and practices, injection initiation episode, HIV injection- and sex-related risk, health care utilization among others. We used bivariate and multivariate analyses to examine factors associated being a late initiate. RESULTS In our sample, 19% of participants who were 30 years or older were classified as late initiates. In multivariate analysis controlling for city, late initiates had higher odds of being female and African American, having been in treatment prior to initiation, initiating illicit drug use at an older age, and being assisted into injection by someone of the same age or younger. Late initiates had lower odds of frequent recent injection, and having a bipolar disorder diagnosis. CONCLUSION Late initiates comprise a significant proportion of active PWIDs. More study on the health consequences of late initiation are needed as are interventions to prevent transition to drug injection among at-risk populations.

Background Clinical, experimental, and ethnographic research suggests that cannabis may be used to help manage pain. Ethnographic research has revealed that some people are using cannabis to temper their illicit opioid use. We seek to learn if there is an association between cannabis use and the frequency of nonmedical opioid use among people who inject drugs (PWID). Methods PWID were recruited using targeted sampling methods in Los Angeles and San Francisco, California, 2011–2013. We limited analysis to people who used opioids in past 30 days (N=653). Outcome variable: number of times used any opioids non-medically in past 30 days. Explanatory variable: any cannabis use past 30 days. Statistics: multivariable linear regression with a log-transformed outcome variable. Results About half reported cannabis use in the past 30 days. The mean and median number of times using opioids in past 30 days were significantly lower for people who used cannabis than those who did not use cannabis (mean: 58.3 vs. 76.4 times; median: 30 vs 60 times, respectively; p<0.003). In multivariable analysis, people who used cannabis used opioids less often than those who did not use cannabis (Beta: −0.346; 95% confidence interval: −0.575, −0.116; p<0.003). Conclusions There is a statistical association between recent cannabis use and lower frequency of nonmedical opioid use among PWID. This may suggest that PWID use cannabis to reduce their pain and/or nonmedical use of opioids. However, more research, including prospective longitudinal studies, is needed to determine the validity of these findings.

Aims Injection drug use initiation typically involves an established person who injects drugs (PWID) helping the injection-naïve person to inject. Prior to initiation, PWID may be involved in behaviors that elevate injection initiation risk for non-injectors such as describing how to inject and injecting in front of injection-naïve people. In this analysis, we examine whether PWID who engage in either of these behaviors are more likely to be asked to initiate someone into drug injection. Methods Interviews with PWID (N=602) were conducted in California between 2011 and 2013. Multivariate analysis was conducted to determine factors associated with being asked to initiate someone. Results The sample was diverse in terms of age, race/ethnicity, and drug use patterns. Seventy-one percent of the sample had ever been asked to initiate someone. Being asked to initiate someone was associated with having injected in front of non-injectors (Adjusted Odds Ratio [AOR]=1.80, 95% Confidence Interval [CI]=1.12, 2.91), having described injection to non-injectors (AOR=3.63; 95% CI=2.07, 6.36), and doing both (AOR=9.56; 95% CI=4.43, 20.65) as compared to doing neither behavior (referent). Being male (AOR=1.73; 95% CI=1.10, 2.73) and non-injection prescription drug misuse in the last 30 days (AOR=1.69; 95% CI=1.12, 2.53) were also associated with having been asked to initiate someone. Conclusion Reducing initiation into injection drug use is an important public health goal. Intervention development to prevent injection initiation should include established PWID and focus on reducing behaviors associated with requests to initiate injection and reinforcing refusal skills and intentions among established PWID.