A Systematic Scoping Review of Research on Black Participants in the National Drug Abuse Treatment Clinical Trials Network

Abstract

Black individuals experience a disproportionate burden of substance-related disabilities and premature death relative to other racial/ethnic groups, highlighting the need for additional research. The National Drug Abuse Treatment Clinical Trials Network (CTN), a research platform for multi-site behavioral, pharmacological, and integrated trials designed to evaluate the effectiveness of substance use treatments in community settings with diversified patient populations, provides a wealth of research knowledge on substance use. Although CTN trials have enrolled over 5,000 Black individuals since its inception in 2000, there has been no synthesis of the findings, discussion of the implications, or suggestions for future research for Black individuals. Members of the Minority Interest Group (MIG) of the CTN conducted a scoping review of published research on Black participants in CTN trials. Studies were included if the sample was 75%+ Black and/or specific findings pertaining to Black participants were reported. The review yielded 50 articles, with studies that mostly focused on baseline characteristics, followed by substance use treatment outcomes, HIV/risky sex behaviors, retention, comorbid conditions and measurement issues. This review highlighted the importance of several issues that are critical to understanding and treating substance misuse among Black people, such as the characteristics of Black people entering treatment, measurement equivalence, and engaging/retaining adolescents and young adults in treatment. There is still a continued need to identify the most effective treatments for Black individuals who use substances. The CTN offers several untapped opportunities to further advance research on Black individuals who use substances (e.g., secondary analyses of publicly available data).

INTRODUCTION

Despite the detrimental effects of substance use observed across all racial/ethnic groups, Black individuals experience a disproportionate burden of substance-related disabilities and premature death (Kandel, Hu, Griesler, et al., 2017; Keen, Khan, Clifford et al, 2014) and Blacks with more severe substance use problems are less likely than Whites to receive treatment (Schmidt, Ye, Greenfield et al., 2007). Black individuals are frequently underrepresented in substance use treatment studies, and when they are represented, researchers often fail to conduct moderator or subgroup analyses by race, which contributes to gaps in knowledge about substance use treatment for Blacks. Further, research findings conducted using predominantly White samples are frequently applied to racial/ethnic minority populations (Lambert et al., 2004) despite racial/ethnic variation in the etiology of substance use disorders (SUDs) that may limit the generalizability of findings based on Whites to racial/ethnic minorities (Curtis-Boles & Jenkins-Monroe, 2000, Lambert et al., 2004). Nevertheless, the limited available research revealing meaningful racial/ethnic differences in contextual factors (Lambert, et al., 2004), etiology (Bell & McBride, 2012; Curtis-Boles & Jenkins-Monroe, 2000), risk factors (Curtis-Boles & Jenkins-Monroe, 2000; Lister, Greenwald, & Ledgerwood, 2017), treatment retention (Davis & Ancis, 2012; SAMHSA, 2013; Saloner & Le Cook, 2013), response to treatment (Amaro, 2007; Calsyn et al., 2012) and health, social and legal consequences of drug use (Blakey, 2011; Davis & Ancis, 2012; Stuntz, 2008) argues for research on specific racial/ethnic groups. Accordingly, the strategic plan of the National Institute on Drug Abuse (NIDA, 2015) calls for more research on the causes and effective treatments of SUDs among racial/ethnic minorities at high risk for problematic substance use (Lister et al, 2017). Thus, this review addresses this gap in the literature by focusing specifically on Black individuals who use substances.

Existing reviews of substance use among Black people are limited in scope. Specifically, these reviews focused narrowly on specific subgroups such as youth (Chipungu, Herman, Sambrano, Nistler, Sale, & Springer, 2000; Lee, Cintron and Kocher, 2014; Lauricella, Valdez, Okamoto, Helm & Zaremba, 2016), rural adolescents (McBride Murry, Liu, Bethune, 2016), incarcerated males (Lichtenstein, 2009), rural males (Brown & Smith, 2006), females (Davis & Ancis, 2012) or individuals with alcohol use disorder (Sutherland, 2010). The one comprehensive review of 23 articles was limited to research conducted by social workers, focused only on substance use interventions, and few of the samples were exclusively Black (Clark, McGovern, Mgbeokwere, Wooten, Owusu, and McGraw, 2014). In addition, although some studies in existing literature reviews were multisite, many were single-site studies.

The National Drug Abuse Treatment Clinical Trials Network (CTN) of the National Institute on Drug Abuse (NIDA) was developed to improve the quality of drug treatment in the U.S. (Wells et al., 2010), and thus has the potential to play a significant role in addressing several gaps in the literature on substance use among Black individuals. The CTN includes multisite behavioral, pharmacological, and integrated research projects aimed at evaluating the effectiveness of alternative treatment interventions in community settings with diversified patient populations. As of May 2019, 5,804 Black individuals had participated in CTN protocols. Two important strengths of CTN studies related to this review include the use of multisite randomized clinical trials, which increases the generalizability of their findings, and the ability for CTN investigators to conduct secondary analyses examining moderation or subgroup analyses by race/ethnicity. Because the purpose of the CTN is to use science to improve drug treatment, it is important that CTN research informs drug treatment outcomes for all, including Black people. However, there have been no reviews of the CTN to ensure that Black people are benefitting equitably from CTN research.

The aim of the Minority Interest Group of the CTN is to ensure racial/ethnic minorities benefit equitably from the knowledge gained from CTN research. Given that no study has synthesized the information about Black individuals participating in CTN trials, the actual contribution of the CTN to understanding the etiology and treatment of substance use among Black people has not been fully realized.

Scoping reviews are designed to synthesize research evidence to convey the breadth and depth of a field (Levac, 2010; Tacconelli, 2010), and differ from traditional systematic reviews in that they provide a map of the literature without quality assessment or extensive data synthesis (Armstrong, Hall, Doyle et al., 2011). Several reasons have been cited for undertaking a scoping review including a need to summarize and disseminate findings and to identify gaps in existing literature that has not yet been comprehensively reviewed (Arskey & O’Malley, 2005; Peters, Godfrey, Khalil et al., 2015). Given our lack of synthesized findings on substance use among Black participants in the CTN, a scoping review is the appropriate vehicle for compiling an overview of CTN studies and for identifying gaps in research on substance use among Blacks. Thus, the aim of the current study was to conduct a scoping review to determine what has been learned from CTN data about Black individuals who use substances.

METHODS

A scoping review, following the methodological framework of Arskey and O’Malley (2005), was conducted on Black participants enrolled in multisite randomized clinical trials in the CTN. Given the lack of existing reviews of CTN data among Black participants, the research question was purposefully broad to capture a wide range of findings in this population. Thus, the research question that guided this review was: What have we learned from published CTN studies about Black individuals who use substances?

Study Identification and Selection

Given that this review focuses specifically on studies conducted within the CTN, the primary source for identifying articles was the CTN Dissemination Library (http://ctndisseminationlibrary.org/). To ensure a comprehensive literature search, studies were also identified through PubMed, PsycINFO, and Google Scholar using the following search terms: (“African American” OR “Black”) AND (“NIDA CTN” OR “National Institute on Drug Abuse Clinical Trials Network” OR “National Drug Abuse Treatment Clinical Trials Network”) in the title or the abstract. Backward searches were also conducted (i.e., reviewing the references of articles that met inclusion criteria in the initial search). The last search took place on 4/4/2019. Studies met inclusion criteria if they were (1) published CTN studies and (2) at least 75% of the sample was Black and/or reported findings specifically on Black individuals. If studies included race/ethnicity as a moderator but categorized race as “White and Non-White” or did not explicitly compare Black participants to another racial/ethnic group, they were excluded. Review articles and studies that focused on substance use program or workforce characteristics were also excluded.

As shown in Figure 1, 174 articles were identified through several scientific databases. Two independent reviewers assessed the titles and abstracts for all 174 articles to determine if they met inclusion criteria. A third reviewer was consulted when there was disagreement. A total of 124 articles were excluded because they did not meet one or more of the inclusion criteria listed above. Therefore, 50 studies were included in the present review.

Figure 1.

Flow diagram for search strategy.

Charting the Data

The data were charted according to common themes. First, a descriptive summary of each study was provided to identify themes (Table 1). Second, after a thorough review of Table 1, the studies were organized thematically (described below). Notably, some studies (k = 9) were categorized in more than one theme. In these cases, the specific findings from each study were categorized and presented under their respective themes.

Table 1.

Systematic Scoping Review on Black Participants Enrolled in Multisite Trials Conducted Within the National Drug Abuse Treatment Clinical Trials Network (CTN)

CTN #	Article	Total # of Participants	% Black	Age (M, SD)	%Women	Inclusion Criteria	Treatment	Findings among Blacks
Baseline Characteristics
0001, 0002, 0005, 0006, 0007	Brooks et al., 2010	1429	36.90%	Overall range: 18.1–73.2; Overall Mean: 37.2 (9.7)	Overall: 45% Black: 39.3%	(1) patients engaging in multi-site trials between 2001 and 2005 upon treatment entry; (2) primary outcome of interest was HIV risk behaviors	Buprenorphine/Naloxone, Motivational Enhancement Therapy, Motivational Interviewing, Motivational Incentives	(1) Women were more likely to be White (51% vs. 47%) or Black (39% vs 36%)
0044	Campbell et al., 2017	507	22.10%	Black: 38.1 (10.4)	Blacks: 40.18%	(1) 18 or older, (2) using illicit substances in the 30 days prior to study entry (or 60 days if the patient was exiting a controlled environment), (3) within 30 days of entering the treatment episode, and (4) proficient in English	Therapeutic Education System	(1) Black adults appeared to be older than White, Hispanic, Multiracial, and Other adults, (2) Greater coping skills for Black participants who were abstinent at study entry (baseline negative)
0037	Chartier et al., 2015	302	51.9% men; 29.75% women	Overall: 35.67 (9.9) for women; 41.17 (10.8) for men	Overall: 40.0%; Blacks: 29.75%	(1) reported illicit stimulant drug use (e.g., cocaine, methamphetamine, or amphetamine) in the 30 days prior to residential treatment program entry, (2) received medical clearance for exercise	Stimulant Reduction Intervention using Dose Exercise (STRIDE)	(1) Black race/ethnicity was associated with lower abstinence symptom severity relative to non-Blacks
0044	Cochran et al., 2014	494	22% at baseline Overall drug test positive: 26.7%; Overall drug test negative: 19.6%	Overall: 35 (11)	Overall: 38%	(1) adults (18 years or older) within the first 30 days of their current treatment episode who self-reported illicit substance use in the preceding 30 days, were proficient in English, (3) were planning to remain in the treatment program for at least 3 m	Therapeutic Education System	(1) Black and Hispanic adults were more likely than their White counterparts to test positive for baseline drug use
0006	Killeen, et al., 2007	410	41.7%	Overall less treatment experience: 34.6 (8.9); Overall more treatment experience: 37.2 (8.0)	Overall less treatment experience: 47%; Overall more treatment experience: 68%	(1) new intake to a drug-free community-based treatment program, (2) any reported cocaine or methamphetamine use in past two weeks or positive urine screen (any stimulant use within two weeks of entering controlled environment, if applicable)	Motivational Incentives	(1) Treatment experienced participants were more likely to be Black relative to individuals with less prior treatment episodes
0053	McClure et al., 2017	302	27.8%	30.3 (9.0)	28.5%	(1) between the ages of 18–50, (2) able to provide informed consent, (3) met DSM-IV criteria for cannabis dependence, (4) were treatment seeking (for cannabis) and (5) had a positive urine toxicology result for THC at screening	N-acetylcysteine (versus data from 3 national datasets)	CTN 0053 clinical trial had higher representation of Black adults compared to national household surveys
0053	Montgomery et al., 2019	377	27.3%	30.2 (8.9)	27.6%	(1) between the ages of 18–50, (2) able to provide informed consent, (3) met DSM-IV criteria for cannabis dependence, (4) were treatment seeking (for cannabis) and (5) had a positive urine toxicology result for THC at screening	N-acetylcysteine	(1) Based on screening/baseline data, Black individuals were more likely than their White counterparts to report blunt use
	Pagano et al., 2018	1,840	19.2%	Blacks: 44.9 (12.54)	Blacks: 39.6%	Clients who participated in programs that were (1) publicly funded, (2) had at least 60 active clients and (3) the program director agreed to participate in the study and assigned a staff liasion to coordinate data collection with the study team	Survey of 24 CTN addiction programs	(1) Black adults relative to Whites were less likely to be daily smokers and to have used NRT, but more likely to be menthol cigarette users and to report having made a past-year quit attempt, (2) Black adults smoked fewer cigarettes per day compared to Whites, (3) Blacks adults were less likely to have used smokeless tobacco and e-cigarettes, but were more likely to have smoked cigars in the past month, (4) Blacks were more likely than Whites to have endorsed the statement “The best point to stop smoking in drug treatment is as soon as treatment begins” and report higher receipt of smoking cessation services
0031	Peavy et al., 2017	395	43.3%	Overall: 39.1 (9.8); Blacks: 42.7 (8.7)	Overall: 58.7%; Blacks: 53.2%	(1) age 18 years or older, (2) in outpatient treatment at participating community-based treatment programs, (3) stimulant drug use within the past 60 days (or within the past 90 days if incarcerated during the past 60 days), (4) DSM-IV diagnositic criteria for current (within the past 6 months) abuse or dependence on a stimulant drug as primary or secondary drug of abuse, 5) able to provide consent and willing to participate	Stimulant Abuser Groups to Engage in 12-Step (STAGE-12)	(1) Black participants were older and more likely to report cocaine as their primary substance relative to White participants; (2) Black adults reported higher levels of spirituality and indicated more perceived benefits of twelve-step involvement compared to White adults, (3) No significant treatment differences in abstinence or in the rate of stimulant and nonstimuluant use among Black and White adults
0007	Petry et al., 2006	803	Non-methdone clinic patient non-gamblers: 38.8%; Nonmethadone clinic patient gamblers: 51.9%; Methadone clinic patient non-gamblers: 38.8%; Methadone clinic patient gamblers: 70.4%	Non-methdone clinic patient non-gamblers: 35 (8.4); Nonmethadone clinic patient gamblers: 38 (9.2); Methadone clinic patient non-gamblers: 40.8 (8.7); Methadone clinic patient gamblers: 44 (7.9)	Over all Non-methdone clinic patient non-gamblers: 60.9%; Nonmethadone clinic patient gamblers: 39.8%; Methadone clinic patient non-gamblers: 53.3%; Methadone clinic patient gamblers: 47.2%	(1) recent stimulant use or positive urine sample, (2) able to understand study procedures by passing an informed consent quiz with a score of 80% or better, (3)denied being in recovery for gambling addiction	Motivational Incentives	(1) Black adults in methadone clinics were more likely to gamble than White, Hispanic and Other race adults
0027	Potter et al., 2013	1250	Heroin Only: 10.8%; Opioid Analgesic only: 5.3%; H& OA: 6.7%; Non injectors: 11.4%;Injector s: 7.4%; No use: 7.7%; Use: 13.8%	Heroin Only: 38.2 (10.9); Opioid Analgesic only: 34.4 (10.1); H& OA: 37.1 (11.6); Non injectors: 35.4 (10.4);Injectors: 38.3 (11.3); No use: 38.6 (11.2); Use: 38.3 (11.5)	Heroin Only: 30.4%; Opioid Analgesic only: 38.8%; H& OA: 31.8%; Non injectors: 37.4%;Injectors : 29.8%; No use: 34.2%; Use: 29%	(1) adults (at least 18 years old) (2) endorsing substance use in the past 30 days	START	(1) Participants using opioids were more likely to be Black
0015	Ruglass et al., 2014	141	46.10%	Overall 41.01 (9.02)	100	(1) Reported stimulant use within 30 weeks of study entry	Seeking Safety	(1) Light Users (n=79) Black 44.30%; (2) Heavy Users (n=62) Black 48.39%; There were no significant differences between light and heavy users on any social demographics
0053	McClure et al., 2018	762	39.0%	30.3 (9.0)	26.7%	(1) between the ages of 18–50, (2) able to provide informed consent, (3) met DSM-IV criteria for cannabis dependence, (4) were treatment seeking (for cannabis) and (5) had a positive urine toxicology result for THC at screening	N-acetylcysteine (versus data from 3 national datasets)	CTN 0053 clinical trial had higher representation of Black adults compared to national household surveys
0053	Montgomery et al., 2020	770.0714286	42.8%	30.2 (8.9)	25.8%	(1) between the ages of 18–50, (2) able to provide informed consent, (3) met DSM-IV criteria for cannabis dependence, (4) were treatment seeking (for cannabis) and (5) had a positive urine toxicology result for THC at screening	N-acetylcysteine	(1) Based on screening/baseline data, Black individuals were more likely than their White counterparts to report blunt use
0007	Wu et al., 2008	383	49%	Overall: Ages 18–35: 45%; 36–50: 49%; >50: 7%	Overall: 45%	(1) opioid dependent patients enrolled in methadone maintenance treatment for at least 30 day no longer than 3 years (1095 days), (2) provided positive stimulant urine samples within two weeks of study entry, (3) denied being in recovery for gambling addiction, and (4) able to understand study procedures by passing an informed consent quiz with a score of 80% or better.	Motivational Incentives	(1) Black participants had significantly less past-month illicit methadone use than White participants
0006, 0007	Wu et al., 2011	682	52.8%	Overall: 39.8 (0.34)	Overall: 51.3%	(1) reported stimulant use within 2 weeks of study entry, (2) used stimulants within two weeks of entering a controlled environment and exited it within 2 weeks of study entry, (3) submitted a strimulant-positive urine at treatment entry, (4) denied having or being in recovery from a gambling problem, (5) demonstrated understanding of study procesures	Motivational Incentives	(1) Cocaine users were more likely to be Black, (2) Black participants were more likely to report an inability to cut down cocaine use compared to White participants
Comorbid Conditions
0015	McHugh et al., 2014	353	Seeking Safety: 33%; Womens Health Education: 35%	Seeking Safety: 39.36 (9.5); Womens Health Education: 39.04 (9.12)	100	(1) patients between 18–65, meeting DSM-IV criteria for Full or Subthreshold PTSD; (2) must endorse substance abuse within past 6 months; (3) have a diagnosis of drug or alcohol dependence (4) English speaking	Seeking Safety	(1) Black women were less likely than White women to report nightmares
0044	Sanchez et al., 2015	507	Overall positive depression screening: 18.9; Overall negative depression screening: 22.9	Overall positive depression screening: 36.5 (10.3); Overall negative depression screening: 34.5 (11.0)	Overall positive depression screening: 45.7%; Overall negative depression screening: 35.9%	(1) adults (18 years or older) within the first 30 days of their current treatment episode who self-reported illicit substance use in the preceding 30 days, were proficient in English, (3) were planning to remain in the treatment program for at least 3 months	Therapeutic Education System	(1) No significant differences in the prevalence of positive versus negative screens for depression among Black participants
0027	Schulte et al., 2015	1039	8.60%	32.10%	37.4 (11.1)	(1) opioid dependent patients enrolled in methadone maintenance treatment (2) primary outcome was HCV serostatus	START	(1) Compared to White individuals, African American individuals were more likely to exhibit HCV +/+
0037	Warden et al., 2016	302	46.3%	39 (10.8)	Overall: 40.1%	(1) Treatment seeking adults age 18–65; (2) endorsing psychostimulant use in past 30 days; (3) meeting DSM-IV criteria for stimulant abuse or dependence in past 12 months	STRIDE	(1) Black participants were less likely to have two or more psychiatric diagnoses compared to 0 or 1 psychiatric diagnoses
Measurement
0004, 0005	Dillon et al., 2015	389	50.1%	Overall: 35.93 (10.2); Blacks: 37.90 (10.0)	Overall: 29%	(1) seeking outpatient treatment for any substance use disorder, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol, (5) able to understand and provide writen informed consent	Motivational Enhancement Therapy (MET)	(1) Partial strong/scalar invariance and partial strict metric invariance was demonstrated on SIP-R between Black and Non-Latino White adults
0004	Kiluk et al., 2013	886	26.70%	Overall: 33.8 (10.2)	Overall: 35%	(1)English speaking, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol contacted for follow-up and have sessions audiotaped	Motivational Enhancement Therapy (MET)	(1) No significant difference in SIP-R total scores across Black, White, Hispanic, Multiracial, and Other race individuals
0047	Sharma et al., 2016	1285	N/A	N/A	N/A	(1) Partcipants in 0047 study, completed TFLB at 3, 6, and 12 mo followup		(1) Black participants and individuals in the other combined racial/ethnic group had greater odds of providing a hair sample, (2) Black adults who used prescription opioids had greater odds of under-reporting use given a positive hair sample, (3) Black adults who used prescription and street opioids were less likely to overreport use given a negative hair sample
HIV/Risky Sex Behavior
0019	Ahuama-Jonas et al., 2017	124	100%	37.56 (10.14)	100	(1) adults (at least 18 years old) (2) English proficient, (3) Capable of understanding informed consent, (4)Enrolled in substance abuse treatment, (5) Endorsed at least one unprotected heterosexual vaginal or anal sex occasion in the past 6 months	Safer Sex Skills Building	(1) Adults sexual abuse among Black women predicted relationship control and decision making dominance factors
0019	Campbell et al., 2012	513	24.30%	40 years or older: 45.8%	100	(1) adults age 18 or older, (2) English proficient, (3) enrolled in drug treatment, (4) reported at least one unprotected vaginal or anal intercourse with a male partner in the past 6 months prior to study entry	Safer Sex Skills Building	(1) Black women reported higher decision-making scores on the sexual relationship power scale than White women, (2) There was no significant differences among racial/ethnic groups on the relationship control scale
0019	Cohen et al., 2009	214	16.40%		100	(1) adults age 18 or older, (2) English proficient, (3) enrolled in drug treatment for at least 30 days to ensure methadone dose stability (4) reported at least one unprotected vaginal or anal intercourse with a male partner in the past 6 months prior to study entry.	Safer Sex Skills Building	(1) Black participants reported significantly fewer unprotected sexual occasions than White participants
0018, 0019	Crits-Christoph et al., 2014	1669	26%	39 ()	Randomized Sample 5 sessions: 46% Randomized Sample 1 session: 47% Analysis Sample 5 Sessions: 44.8%; Analysis Sample 1 session: 48.3%	(1)adults 18 years old, English speaking, enrolled in drug treatment, (2) self-report of engaging in unprotected vaginal and anal sex in the past 6 months,(3) agree to be randomly assigned to study intervention groups.	Real Men Are Safe Safer Sex Skills Building	(1)Black adults (compared to non-Black adults) were more likely, following either intervention, to engage in unprotected sex at least once, (2) Among those with at least one unprotected sex occasion, African American adults had fewer unprotected sex occasions (compared to non-Black adults)
	Kyle et al., 2015	1224	27%	Overall: 40.6 (12.4)	Overall: 33%	(1)participants were required to be 18 years or older; (2) English proficient to provide consent and complete survey.		(1) Black adults relative to their White counterparts were more likely to be tested within the last 12 months
0018	Wilson et al., 2011	126	100.0%	43.4 (10.7)	0.0%	For the purposes of the secondary analysis: (1) be 18 or older, (2) acknowledge engaging in unprotected vaginal or anal intercourse in the prior six months on the Risk Behavior survey, (3) be willing to attend HIV/STI prevention groups, (4) be willing to complete assessments at baseline and at two weeks, three months and six months post intervention, (5) be enrolled in substance abuse treatment	Real Men are Safe (REMAS)	(1) The endorsement of both personal and social masculinity predicted more unprotected sexual occassions with casual partners, (2) The perception that condoms decreased sexual pleasure also predicted higher unprotected sexual occasions (USO) with casual partners, (3) Fewer partner barriers was not associated with USO among casual partners, (4) Neither the endorsement of social or personal masculinity or perceived condom barriers predicted USO with main partners
Substance Use Treatment Outcomes
0004	Burlew et al., 2013	194	100.0%	37.5 (9.9)	24.7%	(1) seeking outpatient treatment for any substance use disorder, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol, (5) able to understand and provide writen informed consent, (6) self-identify as African American or Black (for this secondary project)	Motivational Enhancement Therapy (MET)	(1) Among the high readiness to change (RTC) participants, MET participants reported few days of substance use over time relative to those in treatment as usua (TAU) (2) Among the lower RTC participants, the TAU group reported fewer days of substance use over time compared to those in MET
0027-A-1	Crist et al., 2013	643	12.0%	Blacks in Methadone: 47.8 (8.7); Blacks in Buprenorphine: 47.4 (9.8)	Blacks in Methadone: 27.8%; Blacks in Buprenorphine : 34.1%	(1) being age 18 or older, (2) meeting DSM-IV-TR criteria for opioid dependence, (3) not having an alanine amino transferase (ALT) or aspartate amino transferase (AST) value > 5 times or alkaline phosphatase (ALP) value > 3 times the upper limit of normal	Buprenorphine/Naloxone and Methadone	(1) Black adults had significantly more opioid-positive urine tests than White adults when treated with either methadone or buprenorphine, (2) Among Black adults who were treated with buprenorphine, individuals with the CC genotype at rs678849 had significantly more positive opioid urine test results during 24 weks of treatment than individuals in the combined and TT genotypes group, (3) Among Black adults, the intronic SNP rs678849 predicted treatment outcome for both medications
0027, 0050	Hser et al., 2017	795	9.2%	Overall: 37.4 (11.2)	Overall: 34.1%	(1) being age 18 or older, (2) meeting DSM-IV-TR criteria for opioid dependence, (3) not having an alanine amino transferase (ALT) or aspartate amino transferase (AST) value > 5 times or alkaline phosphatase (ALP) value > 3 times the upper limit of normal	Buprenorphine/Naloxone and Methadone	(1) Greater odds of being in the high opioid use group was associated with Hispanic individuals relative to Black individuals
0001, 0002, 0003, 0004, 0005, 0006, 0007, 0013	Korte et al., 2011	1,897	36.8%	Not reported	Overall: 45.2%	(1) databases were locked and had been posted to the Clinical Trials Network (CTN) data sharing repository, (2) primary outcome of interest was illicit drug use during follow up, comparing randomized treatment and control groups, (3) primary results were published and posted to the CTN dissemination repository	Buprenorphine/Naloxone, Motivational Enhancement Therapy, Motivational Interviewing, Motivational Incentives	(1) Positive intervention effect on the percent of negative urine drug screens during follow-up among Black women
0004	Lee et al., 2014	289	Overall good outcome: 43.4%; Overall poor outcome: 39.0 %; Overall good outcome effective: 64.7%; Overall good outcome ineffective: 9.4%	Overall Good outcome: 35.99 (10.66); Overall Poor Outcome: 33.43(11.02); Overall good outcome effective: 36.31 (10.98); Overall good outcome ineffective: 35.48 (10.30)	Overall good outcome: 26.5%; Overall poor outcome: 33.9%; Overall good outcome, effective: 21.6%; Overall good outcome ineffective: 34.4%	(1) seeking outpatient treatment for any substance use disorder, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol, (5) able to understand and provide writen informed consent, (6) study used information on participants with no missing data (for this secondary project)	Motivational Enhancement Therapy (MET)	(1) Black adults appeared to receive more benefits from MET than White adults
0004	Montgomery et al., 2014	387	50.1%	Overall: 35.5 (10.2); Blacks: 37.5 (9.9)	Overall: 29.2%; Blacks: 24.7%	(1) seeking outpatient treatment for any substance use disorder, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol, (5) able to understand and provide writen informed consent, (6) self-identify as African American or Black or White (for this secondary project)	Motivational Enhancement Therapy (MET)	(1) Black participants rated 9 out of 12 treatment components as being more helpful than their White counterparts, even after controlling for age, gender, employment status, primary drug type and treatment assignment, (2) Perceived helpfulness ratings were not associated with substance use outcomes among Black participants
0009	Reid et al., 2011	153	28.0%	Overall: 41.6 (10.2)	49.0%	(1) 18 years of age or older, (2) smoked at least 10 cigarettes/day, (3) had an interest in quitting smoking, (4) were in substance abuse treatment for at least 30 days prior to enrollment, (4) no medical conditions contraindicated for nicotine partches, (5) limited to participants who were in smoking cessation treatment arm of the study (for the purposes of this secondary analysis)	Smoking Cessation Treatment plus transdermal nicotine patches	(1) Abstinence during treatment was positively associated with Hispanic or White race/ethnicity (as opposed to Black)
Retention
	Korte, Rosa et al., 2011	11,449	21.2%	Overall: <18: 6.4%; 18 to 24: 14.2%; 25–35: 26.1%	Overall: 40.6%	(1) First 24 CTN completed multisite clinical trials	Wide range of behavioral and medical trials	(1) Non-Hispanic White and Hispanic adults remain in certain studies longer than Black adults
0001, 0002, 0005, 0006, 0007, 0008, 0011	Margruder et al., 2009	1737	36%	Overall: Ages 1835: 45%; 36–50: 49%; >50: 7%	Overall: 42%	(1) databases were locked and had been posted to the Clinical Trials Network (CTN) data sharing repository, (2) primary outcome of interest was CTN study retention rates by race/ethnicity, age, and client characteristics that might impact retention rates	Buprenorphine/Naloxone, Motivational Enhancement Therapy, Motivational Interviewing, Motivational Incentives, Telephone Enhancement Procedure	(1) Younger Black adults have significantly lower retention rates in treatment studies relative to other racial/ethnic groups, (2) No significant differences in study retention between all Black adults and non-Hispanic White adults
0004	Montgomery et al., 2017	194	100%	Black: 37.52(9.98)	Black: 24.7%	(1) seeking outpatient treatment for any substance use disorder, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol, (5) able to understand and provide writen informed consent	Motivational Enhancement Therapy (MET)	(1) Overall the more readiness to change increased, the longer Black participants were likely to remain in treatment
0004	Petry et al., 2008	1687	Overall contingency management study: 17.5% Overall MET study: 7.7%	Overall contingency management study: <=38 years: 13.8%; 39 years or older: 15% Overall MET study: <=34 years: 8.7%; 35 years or older: 11.6%	Overall contingency management study: 19% Overall MET study: 11.9%	(1) seeking outpatient treatment for any substance use disorder, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol, (5) able to understand and provide writen informed consent	Motivational Enhancement Therapy (MET)	(1) No significant difference in the incident rate of serious adverse events between Black and White participants
0013	Robbins et al., 2011	480	22.9%	Overall: 16.0 (1.3)	Overall: 21.5%	Adolescents who (1) self-report illicit drugs (other than alcohol or tobacco) in the 30-day period that preceded the baseline assessment or be referred for an institution for the treatment of substance abuse, (2) provide assent and a parent or legal guardian had to provide informed consent to participate in therapy, (3) living with a famility and in the same geographical area as the study site	Brief Strategic Family Therapy	(1) Black adolescents were more likely to fail to engage in treatment, (2) Black adolescents were also more likely than White adolescents to fail to retain
Multiple Themes
0001, 0002, 0004, 0005, 0006, 0007, 0021	Brooks et al., 2013	2,063	32.0%	Overall range: 18.1–73.2; Blacks range: 18.4–65.0	Overall: 35.4%; Blacks: 42%	(1) studies utilized common HIV risk behavior assessment measures	Buprenorphine/Naloxone, Motivational Enhancement Therapy, Motivational Interviewing, Motivational Incentives	BASELINE CHARACTERISTICS AND HIV/RISKY SEX BEHAVIOR: (1) Black adults were older than White and Hispanic adults, more likely to report combined opiate and stimulant use as their primary drug, (2) Alcohol use and legal severity was lowest in non-Hispanic Black adults and length at present address was longest, (3) Black adults were the most likely to report multiple partners, most likely to report tradiing sex and least likely to have unprotected sex with casual partners, (4) Black adults engaged in less HIV sexual risk behaviors overall than White adults, (5) Alcohol use severity was related to engaging in higher sex risk behaviors for Black adults
0003	Brown et al., 2010	724	12.8%	Blacks: 42.5 (9.3)	Blacks: 19.4%	(1) at least 15 years of age, (2) seeking treatment for opioid dependence at one of elevent participating treatment programs in 10 US cities	Buprenorphine	BASELINE CHARACTERISTICS AND RETENTION: (1) Black individuals were more likely to be older, male, have a lower level of education, have a lower rate of employment and report higher rates of lifetime heroin use relative to their White and Hispanic counterparts and less likely to be (2) Lower craving and withdrawal symptoms among Black individuals relative to White and Hispanic individuals, (3) Non-Hispanic White and Hispanic individual reported more adverse events than African American individuals
0004	Dillon, 2013	271	50.9%	Overall: 36.4 (10.3); Blacks: 38.25 (10.1)	28.0%	(1) seeking outpatient treatment for any substance use disorder, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol, (5) able to understand and provide writen informed consent	Motivational Enhancement Therapy (MET)	BASELINE CHARACTERISTICS AND MEASUREMENT: (1) Black participants were older than non-Hispanic White participants, (2) Configural invariance and two forms of metric invariance (weak and strong/scalar), measurement equivalence of the HAQ between Black and non-Latino White participants
0014	Feaster et al, 2010	480	22.9%	Overall: 16.0 (1.3)	Overall: 21.5%	Adolescents who (1) self-report illicit drugs (other than alcohol or tobacco) in the 30-day period that preceded the baseline assessment or be referred for an institution for the treatment of substance abuse, (2) provide assent and a parent or legal guardian had to provide informed consent to participate in therapy, (3) living with a famility and in the same geographical area as the study site	Brief Strategic Family Therapy	BASELINE CHARACTERISTICS AND MEASUREMENT: (1) Black families had significantly higher initial levels of family functioning and lower levels of adolescent externalizing than Hispanic or White familiies, (2) configural and metric invariance of family functioning and externalizing behavior scales across Black, Hispanic and White non-Hispanic families
0004	Montgomery et al., 2011	194	100.0%	37.5 (9.9)	24.7%	(1) seeking outpatient treatment for any substance use disorder, (2) acknowledging substance use within 28 days prior to the study, (3) at least 18 years of age, (4) willing to participate in the protocol, (5) able to understand and provide writen informed consent, (6) self-identify as African American or Black (for this secondary project)	Motivational Enhancement Therapy (MET)	SUBSTANCE USE TREATMENT OUTCOMES AND RETENTION: (1) Higher retention rates among women in MET relative to treatment as usual (TAU) during the initial 12 weeks of the 16 week study, (2) MET participants selfreported more drug-using days per week than participants in CAU
N/A	Montgomery & Carroll, 2017	388	43.20%	Overall: 36.6 (7.8); Blacks: 38.8 (7.3)	Overall: 33.8%; Blacks: 39.3%	(1)Participants in treatment for cocaine dependence, and (2) meeting DSM-IV-TR criteria for cocaine dependence	N/A	BASELINE CHARACTERISTICS AND SUBSTANCE USE TREATMENT OUTCOMES: (1) Black adults reported less number of days of cocaine use 28 days before treatments, less cocaine use, legal, and family problems, and less days paid at work than White adults, (2) Black adults were older than White adults at baseline, endorsed more employment problems, and more likely to be supported by public assistance than White adults, (3) no racial differences in cocaine use treatment outcomes
0015	Ruglass, Hien, et al., 2014	224	45.0%	Overall: 39.4 (9.2); Blacks: 40.8 (7.9)	100.0%	(1) at least one traumatic event in their lifetime and current DSM-IV criteria for full or threshold PTSD, (2) 18–65 years of age, (3) used alcohol or an illicit substance within the 6 months prior to screening and met current diagnosis of drug or alcohol abuse or dependence, (4) capable of providing informed consent	Seeking Safety	BASELINE CHARACTERISTICS AND COMORBID CONDITIONS(1) Black women were younger and had lower education levels than White women, more likely to be single than White women, Blacks more likely to have used stimulants/cocaine in the past month prior to baseline assessment, Black women were prescribed less psychotropic medications than Whites women at baseline (2) Racial/ethnic match did not confer additional benefits for Black clients in terms of PTSD outcomes compared to their counterparts who did not have an individual racial/ethnic match with their therapist
0037	Sanchez, Chartier et al., 2015	290	44.0%	Overall: 39.1 (10.8); Blacks: 44.1 (10.1)	Overall: 39.7%; Blacks: 28.1%	(1) reported illicit stimulant drug use (e.g., cocaine, methamphetamine, or amphetamine) in the 30 days prior to residential treatment program entry, (2) met DSM-IV criteria for stimulant abuse or dependence in the past 12 months, (3) received medical clearance for exercise	Stimulant Reduction Intervention using Dose Exercise (STRIDE)	BASELINE CHARACTERISTICS AND COMORBID CONDITIONS: (1) Black participants were significantly older than White or Hispanic participants, more likely to use alcohol than White participants, had higher higher rates of cocaine use relative to White or Hispanic participants and lower rates of other stimulant use and other illicit dtugs compared to White participants, (2) Black adults were more likely than Hispanic adults to be diagnosed with cocaine abuse or dependence only, less likely to be diagnosed with a cocaine and other stimulant use disorder and more likely to report smoking cocaine than White or Hispanic adults, (3) Black participants endorsed fewer psychiatric disorders and symptoms of depression than White or Hispanic participants and reported a lower risk for sucide than White participats and (4) Black participants reported poorer physical health status and lower cognitive and physical functioning than White participants
0037	Sanchez et al., 2017	297	44.0%	Overall: 39.0 (10.8); Blacks: 44.1 (10.0)	Overall: 40.1%; Blacks: 27.7%	(1) reported illicit stimulant drug use (e.g., cocaine, methamphetamine, or amphetamine) in the 30 days prior to residential treatment program entry, (2) met DSM-IV criteria for stimulant abuse or dependence in the past 12 months, (3) received medical clearance for exercise	Stimulant Reduction Intervention using Dose Exercise (STRIDE)	BASELINE CHARACTERISTICS AND SUBSTANCE USE TREATMENT OUTCOMES: (1) Findings are similar to those reported in #1 and #2 in Sanchez, Chartier et al., 2015 article above, (2) Adherence rate for dose exercise intervention (DEI) was 55% for Black adults (47% for White adults, 47% for Hispanic adults), (3) Probability of stimulant use did not differ between Black and Hispanics or White adults [DEI versus health education intervention], (4) Days of stimulant use differed between White and Black adults, (5) Difference between treatment groups was significantly larger among Black adults than that of Hispanic adults

Collating, Summarizing and Reporting the Results

Six themes were identified across studies: (1) baseline characteristics included studies providing sociodemographic and sociocultural characteristics (e.g., age, sex, primary drug type, stage of change), (2) comorbid conditions characterized studies reporting psychiatric and medical conditions co-occurring with substance use, (3) measurement focused on measurement-related issues (e.g., measurement equivalence) of commonly used CTN assessments, (4) HIV/risky sexual behaviors identified factors associated with risk for HIV, (5) substance use treatment outcomes included within-treatment or follow-up substance use outcomes based on behavioral or medication trials, and (6) retention focused on factors impacting engagement in substance use treatment. Given that multiple studies in this review used data from the same protocols (e.g., seven studies used data from protocol CTN 0004) and the calculation of demographic characteristics varied from study to study (e.g., some studies presented the average age of Black participants in the sample, while others only presented the overall age of the entire sample), there was no meaningful way to aggregate and summarize demographic information for the entire sample. An overall summary and implications of the findings are provided by theme in the following section.

RESULTS AND DISCUSSION

Sample Description

This review identified 50 CTN studies that provided findings specific to Black individuals with SUDs and/or consisted of a sample with 75%+ Black participants. Many studies (48%) described baseline characteristics (k = 24), followed by substance use treatment outcomes (k = 10), HIV/risky sex behaviors (k = 7), retention (k = 7), comorbid conditions (k = 6) and measurement issues (k = 5). Nine of the studies had multiple findings that fell under more than 1 theme. As shown in Table 1, all of the studies were secondary analyses of data from behavioral (Motivational Enhancement Therapy, Motivational Interviewing, Twelve-Step, Motivational Incentives [Contingency Management], Brief Strategic Family Therapy, Therapeutic Education System, Smoking Cessation behavioral counseling, Real Men are Safe, Safer Sex Skills Building, Seeking Safety, or dosed exercise) or medication (Buprenorphine/Naloxone, Methadone or Transdermal Nicotine Patches) trials conducted within the CTN. The majority of studies consisted of adults, with only two studies (4.0%) focusing specifically on outcomes among adolescents.

Baseline Characteristics

CTN studies have demonstrated that Black adults enter treatment (1) at an older age, (2) with higher levels of socioeconomic issues and (3) with a range of self-reported primary drug use. In terms of studies reporting age (Brown et al., 2013; Dillon et al., 2015; Montgomery & Carroll, 2017, Pagano et al., 2018; Peavy et al., 2017; Ruglass et al., 2014; Sanchez et al., 2015; Sanchez et al., 2017), the average age range for Black participants was between 37.9 – 44.9 years. One study, consisting of a sample of women with PTSD and SUD, found Black women were older than their White counterparts (Ruglass, Hien, Hu et al., 2014). Although the findings were somewhat mixed, the findings that Black people enter treatment at an older age were consistent with other non-CTN related observational (Booth, Stewart, Curan et al., 2014; Semple, Amaro, Strathdee et al., 2009) and clinical trial studies (King, 2011; Mitchell, Gryczynski, Kelly et al., 2014) among racially/ethnically diverse and predominantly Black samples. Moreover, as consistent with other non-CTN literature (Acevedo, Panas, Garnick et al., 2018; Mulia, Karriker-Jaffe, Witbrodt et al., 2017), Black adults who use substances reported lower education levels (Brown et al., 2010; Ruglass et al., 2014), lower rates of employment (Brown et al., 2010), more employment problems, higher rates of public assistance support, and less days paid at work than their White counterparts (Montgomery & Carroll, 2017).

Several inconsistencies were found related to primary drug type. Although several studies found higher rates of cocaine use among Black participants (Ruglass et al., 2014; Sanchez et al., 2015; Wu, Pan, Blazer et al., 2011), others revealed lower rates of cocaine use relative to White individuals (Montgomery & Carroll, 2017; Sanchez et al., 2015) and a lower likelihood of cocaine use disorders compared to Hispanic and White people (Sanchez et al., 2015; Sanchez et al., 2017). This inconsistent pattern was also found for other drugs. Two studies found Black participants entered treatment with lower rates of stimulant (Sanchez et al., 2015; Sanchez et al., 2017), and methadone use (Wu, Blazer, Stitzer et al., 2008), while others showed higher rates of current opioid use (Potter, Marino, Hillhouse et al., 2013), other drug use (Cochran, Stitzer, Nunes et al., 2014), blunt use (Montgomery et al., 2019) and lifetime heroin use (Brown et al., 2010) relative to their White, and in some cases, Hispanic, counterparts. Further, one study using data from multiple CTN trials showed higher rates of combined opiate and stimulant use among Black compared to White adults (Brooks, Lokhnygina, Meade et al., 2013). Studies in this review revealed both lower (Brooks et al., 2013) and higher (Sanchez et al., 2015; Sanchez et al., 2017) levels of alcohol use among Black adults relative to their counterparts. Moreover, a survey of clients enrolled in one of 24 CTN addiction treatment programs found racial/ethnic differences in tobacco use, with Black adults less likely to be daily smokers and to have used smokeless tobacco and e-cigarettes than their White counterparts (Pagano et al., 2018). Black adults were also more likely than White adults to smoke menthol cigarettes and cigars in the past month (Pagano et al., 2018).

CTN studies also highlight the consequences of substance use among Black individuals. Specifically, Black participants with opioid dependence reported fewer craving and withdrawal symptoms relative to their White and Hispanic counterparts (Brown et al., 2010). Black participants were more likely to report an inability to cut down on cocaine use (Wu et al., 2011) and reported a lower abstinence symptom severity compared to White participants (Chartier, Sanchez, Killeen et al., 2015).

Interestingly, one study revealed higher representation of Black participants in a CTN clinical trial on cannabis relative to three national samples of individuals who use cannabis (McClure et al., 2017). Although that pattern mandates further investigation, the sample size has the potential to examine more research questions on cannabis use among Blacks.

Other studies examined sociocultural and demographic factors. In terms of sociocultural factors, relative to White participants, Black participants had higher levels of spirituality (Peavy et al., 2017) and gambling rates (Petry, Kolonder, Li et al., 2006), more treatment experience (Killeen, Carter, Copersino et al.,2007), less internet access (Todighi, Campbell, Palicova et al., 2016), fewer legal and family problems (Montgomery & Carroll, 2017), fewer psychiatric disorders and lower suicide risk (Sanchez, Chartier, Greer et al., 2015) and a myriad of other factors (Brooks et al., 2013; Campbell et al., 2017; Feaster, Robbins, Henderson et al., 2010; Pagano et al., 2018; Ruglass et al., 2014). Regarding demographic characteristics, Black participants were more likely to be single relative to White participants (Ruglass et al., 2014). There were higher rates of Black women in CTN trials investigating HIV risk behaviors between 2001–2005 (Brooks et al., 2010) and Black men participating in a CTN trial on stimulant dependence (Winhusen & Lewis, 2013).

In sum, data from CTN studies highlight the need for (1) connecting Black adults to treatment earlier, (2) developing interventions consistent with the sociocultural (e.g., spirituality) and demographic characteristics (e.g., for single adults), (3) linking participants to employment and education assistance to provide the recovery capital known to increase the likelihood of maintaining sobriety (Laudet & White, 2008), and (4) assessing drug use patterns of treatment-seeking Black individuals, including a focus on the effectiveness of existing treatments for Black individuals who use cocaine given the high rate of cocaine-related overdose deaths in this population (Shiels, Freedman, Thomas et al., 2018). The CTN offers an untapped opportunity to provide a sociodemographic profile of understudied groups, including Black people, who present to treatment.

Comorbid Conditions

Six studies provided outcomes associated with multiple psychiatric diagnoses and Hepatitis C virus (HCV) among Black individuals with comorbid SUDs. Warden and colleagues (2016) assessed multiple current comorbid psychiatric disorders (i.e., major depression, dysthymia, mania, hypomania, panic disorder, social phobia, obsessive-compulsive disorder, PTSD or generalized anxiety disorder) and found that Black participants were less likely than White participants to have two or more comorbid psychiatric disorders. Regarding co-occurring PTSD, McHugh, Hu, Campbell et al. (2014) found that Black women were less likely than White women to report nightmares. This finding, despite being based on only one study, highlights the need to further examine racial/ethnic differences in the symptoms associated with PTSD. In terms of treating co-occurring PTSD in women, Ruglass et al., (2014) found a three-way interaction such that White patients with high baseline scores on the Clinical Administered PTSD Scale (CAPS; Blake et al., 1995) who were racially/ethnically matched to their group therapist had greater reductions in PTSD symptoms; however, this finding did not hold for Black women. These findings are somewhat consistent with prior meta-analyses on racial/ethnic matching that found Black patients with a variety of mental health issues had either no or mildly better treatment outcomes when matched to Black therapists (Calabral & Smith, 2011; Maramba & Nagayama, 2002; Shin et al., 2005).

Regarding co-occurring depression, Sanchez and colleagues (2015) found Black individuals represented 18.87% of adults positive for depression and 22.94% of those negative for depression and found no significant differences in the prevalence of depression among White, Black, Hispanic/Latino and Multiracial/Other adults. Sanchez, Cartier, Greer et al. (2015) found endorsement of fewer psychiatric symptoms (including symptoms of depression), lower risk for suicide, and better mental health status among Black compared to White and Hispanic participants.

In terms of co-occurring HCV, Black participants were more likely than White participants to exhibit HCV +/+ (i.e., both antibody and antigen were positive) (Schulte, Hser, Saxon et al., 2015). These findings suggest the importance of drug treatment options that assess for medical conditions and refer for medical treatment as needed. Also, needle exchange programs might conduct agency-wide assessments to determine who is utilizing their services and whether additional steps might be needed to increase access among racially/ethnically diverse individuals, Black individuals in particular.

In summary, these findings highlight the importance of the assessment, diagnosis and treatment of psychiatric disorders and medical conditions comorbid with SUDs among individuals from diverse racial/ethnic backgrounds. Given the evidence that separate programs for addiction and other co-occurring health problems are less effective compared to integrated treatment (Mueser & Gingerich, 2013), additional research on the effectiveness of integrated treatment options, and their availability to Black individuals with SUDs is warranted.

Measurement

Given that measurement equivalence is essential to good science, we applaud the CTN researchers who examined measurement equivalence across racial/ethnic groups for four measures used in the CTN. Although one CTN study found no racial/ethnic differences in total scores on the SIP-R, a measure of the negative consequences from substance use (Kiluk et al, 2013), another study directly assessed measurement equivalence of the measure (Dillon et al., 2015). The authors found partial/strong scalar invariance and partial strict metric invariance on the SIP-R between Black and White adults. Similarly, Dillon (2013) reported configural invariance and two forms of metric invariance (weak and strong/scalar) between Black and non-Hispanic White adults on the HAq-II, a measure of therapeutic alliance. Nevertheless, racial/ethnic differences were evident on the normative levels of four items of the SIP-R and three items of the HAq-II.

Feaster, Robbins, Henderson et al., (2010) found configural and metric invariance across Black, White and Hispanic participants on a problem behavior composite scale and a family functioning composite scale for adolescents and their parents. However, differences in the reliabilities of the factors, the factor variances, and the factor means raise some cautions that require further exploration in future research. Notably, studies external to the CTN have demonstrated some degree of measurement non-equivalence between Black and White adults on two measures used in the CTN (Trauma Symptom Checklist-40; Ghee, Johnson, & Burlew, 2010) and the Condom Use Self Efficacy Scale (CUSE; Lanaway, 2017).

One study also found measurement issues related to hair samples among Black participants. Specifically, the discrepancy between self-report and hair test results varied by drug type. Although Black participants with SUDs overall had greater odds of providing a hair sample relative to their White counterparts, Black participants reporting prescription opioid dependence with positive hair samples had greater odds of under-reporting use compared to their White counterparts. However, Black participants using prescription and street opioid drugs were less likely to over-report use given a negative hair sample than Whites (Sharma et al., 2016). As consistent with other studies (Feucht, Stephens, & Walker, 1994; Ledgerwood et al., 2008), these findings suggest that the rates of disagreement between self-report and hair test results are higher among Black individuals and often varies by drug type. Additional studies are needed to further assess the relationship between race and disagreement between drug use measurement approaches, especially hair testing.

Taken together, the CTN data represents a largely untapped opportunity for investigating measurement equivalence of commonly used assessments in clinical trials. Further, these findings argue for the assessment of measurement equivalence as a standard operating procedure in clinical research.

HIV/Risky Sexual Behaviors

Regarding HIV and risky sexual behaviors among Black women, Ahuama-Jonas et al. (2017) found that a history of sex abuse jeopardizes the sexual relationship power that women may need to protect themselves. However, among Black men, the endorsement of stereotypical masculinity roles appears to be associated with more unprotected sexual occasions with casual partners (Wilson et al., 2011). Together, these findings argue for separate HIV risk reduction interventions for Black males and females in substance abuse treatment in order to focus on the priority domains of each group.

When Calsyn and colleagues (2012) evaluated the efficacy of Real Men Are Safe (REMAS), an intervention aimed at reducing risky sexual behaviors among substance abusing men, they found that the intervention was not as effective for Black compared to White men who misuse substances. However, in a small pilot, they later demonstrated that a culturally adapted version of REMAS had better outcomes (i.e., less unprotected sex) for Black men than the generic version (Calsyn et al., 2013). This finding suggests that culturally appropriate interventions may improve HIV risk reduction and other outcomes for Black men and other target groups.

CTN data also suggests the relationship between HIV risk behaviors, HIV testing, and HIV acquisition is complicated. Although the CDC reports higher rates of HIV among Black than White individuals, CTN data does not consistently support this finding. Brooks et al. (2013) reported the rate of risky or unprotected sexual behaviors is lower among Black compared to White people who use substances; however, the opposite was found by Crits-Cristoph et al. (2014). Additionally, Kyle et al., (2014) found that Black compared to White participants were more likely to have been tested for HIV in the past year. These inconsistent findings suggest that along with projects focusing on HIV risk awareness and HIV testing, both researchers and interventionists may need to explore other factors (e.g., history of sexual abuse, conceptualization of masculinity) related to HIV risk among Black people who use substances.

Substance Use Treatment Outcomes

Ten studies in this review described substance use treatment outcomes among Black participants. Across interventions from multiple CTN trials, Korte et al. (2011) found a lower percent of negative urine drug screens among Black women but not Black men. Black participants receiving Motivational Enhancement Therapy (MET) endorsed more drug using days per week during the study period than those in treatment as usual (TAU) (Montgomery et al., 2011). However, Black participants with high readiness to change scores reported fewer days of substance use in MET than TAU. In contrast, Black participants with low readiness to change scores endorsed fewer days of substance use over time in TAU versus MET (Burlew et al., 2013). These findings suggest clinicians should assess readiness to change to inform treatment plans, especially for Black patients.

In a study assessing the effectiveness of an exercise intervention for adults with stimulant use disorder, Sanchez and colleagues (2017) found that among exercise-adherent participants, Black adults displayed a significantly lower probability of stimulant use in the exercise treatment group relative to those in the health education control intervention. This finding suggests that exercise might improve treatment outcomes among Black adults with stimulant use disorders given adequate levels of adherence.

Inconsistencies were found regarding perceived benefits of substance use treatment among Black participants (Montgomery et al., 2014; Peavy et al., 2017). Specifically, nine out of 12 components of MET were rated as more helpful among Black compared to White participants. Notably, perceived helpfulness ratings were not associated with substance use outcomes among Black adults (Montgomery et al., 2014). In addition, the 12-step model to reduce stimulant use (STAGE-12) was reported as more useful among Black compared to White participants, yet there were no differences in treatment outcomes by race/ethnicity (Peavy et al., 2017). These findings are consistent with prior research suggesting that perception of benefit may not be a good stand-alone indicator of the effectiveness of substance use treatment (Korte et al., 2011; Lee et al., 2014; Montgomery et al., 2014; Peavy et al., 2017).

The available pharmacotherapy studies focused on smoking and opioid use. Secondary analyses of a CTN trial assessing the effectiveness of nicotine replacement therapy indicated the rates of smoking abstention during treatment were higher among White and Hispanic than Black individuals (Reid et al., 2011). These findings suggest the possibility of different factors maintaining tobacco use among Black individuals that need to be identified and targeted in smoking cessation interventions.

In terms of treatment for opioid use, Black adults were less likely to be in the high opioid using group than Hispanic adults (Hser et al., 2017) and had more opioid-positive urine samples while receiving Buprenorphine/Naloxone and Methadone treatment compared to White adults (Crist et al., 2013). Genetic differences of the ORPDF I gene were also assessed among Black participants receiving treatment for opioid use; the CC genotype at the rs678849 intronic SNP gene variant was associated with more opioid-positive urine test results during treatment among those receiving Buprenorphine/Naloxone compared to Methadone (Crist et al., 2013). Moreover, this gene variant predicted treatment outcomes among Black participants in both treatment groups, though the authors expressed the need to replicate these findings in an independent sample (Crist et al., 2013). Despite the increased awareness and focus on opioid treatment, only one study suggests methadone may produce better outcomes relative to Buprenorphine/Naloxone among Black people. Given the limited CTN research available on which treatment protocols are effective for Black participants with opioid use disorder, this should be a focus of future research especially due to the negative impact of opioid overdose among Blacks in multiple parts of the U.S. (Schmitz Bechteler & Kane-Willis, 2017).

Unfortunately, the available CTN research on treatment has not yet identified the most effective treatments for Black individuals. Nevertheless, several conclusions might be drawn from the available findings. First, the efficacy of a behavioral treatment may depend on characteristics other than drug type (e.g., readiness to change). For that reason, when feasible, providers should assess clients on those characteristics before deciding on the preferred treatment. Second, client reports of the benefits of treatment have only limited utility for assessing treatment effectiveness. Finally, although only limited information is available on the efficacy of pharmacotherapy, the CTN research has demonstrated that nicotine replacement therapy is not as effective for Black individuals when compared to White individuals.

Retention

Retention is critical to solid intervention research. Seven studies assessed study retention among Black participants in the CTN. Magruder and colleagues (2009) found no significant differences in study retention between Black and non-Hispanic White participants across six CTN studies. When examining retention in 24 trials including approximately 11,000 participants, the retention rate was under 75% for three retention indicators (baseline assessments, treatment exposure, and follow-up data) and consistently lower among Black compared to Hispanic and White participants, but the differences were not statistically significant. In CTN studies investigating retention in MET, retention was higher among Black women in MET vs. TAU (Montgomery et al., 2011), and high readiness to change was associated with greater retention among Black people in MET (Montgomery et al., 2017).

Regarding retention among Black adolescents and young adults, CTN research on retention among adolescents is limited. However, among adolescents participating in a study testing the effectiveness of BSFT, Black adolescents were less likely to remain in a study testing the effectiveness of BSFT than their White counterparts (Robbins, Feaster, Horigian et al., 2011). Although Magruder et al. (2009) found no overall racial/ethnic differences in retention, younger Black participants demonstrated lower retention. The finding that younger Black participants are the hardest to retain in treatment is consistent with other findings (Peters, Hendricks, Clark et al., 2014).

Overall, the CTN studies suggest that retention is a concern especially among younger Black individuals with substance use problems. We encourage researchers to be aware of the potential for high levels of attrition when recruiting, especially among younger Black participants, and to embed secondary studies in larger studies evaluating the effectiveness of alternative approaches to retaining Black youths. Although the evidence for the efficacy of MET in reducing substance use is limited, the studies reviewed herein suggest that MET and other activities aimed at increasing readiness to change might be effective as preliminary strategies to engage Black adults in treatment. Other approaches to successfully recruit and retain Black participants in clinical trials include using community-based participatory research, which involves including community members in all aspects of the research from formulating research questions, collecting and interpreting data, and disseminating the findings (e.g., De Las Nueces, Hacker, DiGirolamo, & Hicks, 2012; George, Duran, & Norris, 2014; Wallerstein & Duran, 2006; 2010). Researchers could also ensure they have a diverse research team who have had sensitivity training.

CONCLUSION

As with all studies, this review is not without limitations. First, the focus on Black people who use substances in this paper further perpetuates the assumption that Black people are a monolith and negates within group differences (e.g., sex, ethnic identity, nativity). However, even though race is a social construct, it has real consequences particularly as it relates to the development of SUDs and access to treatment for Black people and, thus, is a critical area of study. Future CTN research could benefit from investigating within group differences among Black individuals with SUDs and other substance related concerns. Second, we conducted a scoping review, which is the first step to understanding what is known about Black people with SUD based on CTN research and does not offer prescriptive suggestions on how treatment outcomes might be improved among Black people with SUD. Third, this review was unable to provide specific details on how the sample characteristics were assessed in each study. For example, although we conclude that CTN research suggests Black participants tend to be single, it is unclear how single was defined so we do not know if single represents not having a partner or having a partner but unmarried. Fourth, it is difficult to draw firm conclusions on the existing literature in this area when most of the findings are based on a single study. Additional research is needed replicating many of the findings discussed in this review. Fifth, the focus on CTN studies likely resulted in leaving out other important studies that could inform the findings in this review. However, given that the CTN was developed specifically to use science to improve the quality of drug and alcohol treatment provided in the U.S. (Wells et al., 2010), there is a need to identify and summarize how existing CTN research informs effective treatment approaches for Black people. Sixth, the search strategy involved searching for keywords in the title and abstract, which may have resulted in excluding studies in which the key words were only included in the body of the text. Finally, many of the studies included in this review are based on secondary data analysis, which limits the research questions that can be investigated. Alternatively, utilizing secondary data can be especially informative given the difficulty recruiting large enough samples of Black people who use substances to conduct subgroup analyses.

Despite these limitations, this scoping review provides the first synthesis of existing published NIDA CTN research on Black people who use substances. Overall, the most significant patterns and implications are described below:

1. Racial/ethnic differences in treatment entry. Future research is needed to explore strategies to attract Black individuals to treatment at an earlier age.

2. Racial/ethnic differences in HIV/risky sex related behaviors (e.g., HIV testing, rates of unprotected sexual occasions, response to specific HIV prevention interventions) and within-group gender differences (e.g., predictors of unprotected sex). Culturally based interventions that address the unique HIV-related characteristics that Blacks bring to treatment and gender differences may result in more effective interventions for Black individuals

3. Racial/ethnic differences in measurement. The findings support the benefits of increased measurement equivalence work within the CTN.

4. Racial/ethnic differences in treatment retention. The CTN findings demonstrate the need for further research investigating barriers to retention among Blacks, especially Black youth and young adults.

Perhaps the most significant gap is the limited research available on effective treatment for Black people who use substances. Compiling the knowledge gained from the CTN on Black people increases our understanding of the unique etiological factors that should be considered in developing and implementing effective substance use treatment protocols for Black people, determining which existing treatments are most impactful, and ascertaining gaps in the literature for future research. We were surprised by the limited amount of information on substance use treatment outcomes among Black people. Although the CTN has enrolled 5,804 Black participants, only ten studies provided findings specifically on treatment outcomes among Black people. Many studies simply did not have large enough samples of Black participants. Some studies had a reasonable sample size of Black participants but did not test race/ethnicity as a moderator or conduct subgroup analyses. Previous research both within (Calsyn et al., 2012) and outside (Amaro, Dai, Arevalo et al., 2007) the CTN has demonstrated that interventions effective for one racial/ethnic group may not be as effective for other groups. For that reason, we strongly encourage the CTN to take advantage of its tremendous resource of existing and future CTN data sets to examine the efficacy of interventions for specific racial/ethnic groups.