Brief motivational interviewing for teens at risk of substance use consequences: A randomized pilot study in a primary care clinic

Journal of Substance Abuse Treatment 35 (2008) 53 – 61

Regular article

Brief motivational interviewing for teens at risk of substance use consequences: A randomized pilot study in a primary care clinic Elizabeth J. D'Amico, (Ph.D.)⁎, Jeremy N.V. Miles, (Ph.D.), Stefanie A. Stern, (M.A.), Lisa S. Meredith, (Ph.D.) RAND Corporation, Santa Monica, CA 90407-2138, USA Received 18 April 2007; received in revised form 7 August 2007; accepted 8 August 2007

Abstract The current study examined the impact of a brief motivational interviewing (MI) intervention (Project CHAT) on alcohol consumption and drug use for high-risk teens in a primary care clinic that provides health care for underserved populations. Youth (N = 42, 48% male) were screened, and those eligible completed a baseline survey. Baseline survey completers were randomly assigned to usual care or to an MI intervention and completed a 3-month follow-up survey. The sample (age 12 to 18 years) was 85.7% Hispanic or Latino, 9.5% African American, and 4.8% White. At the 3-month follow-up, Project CHAT teens reported less marijuana use, lower perceived prevalence of marijuana use, fewer friends who used marijuana, and lower intentions to use marijuana in the next 6 months, as compared to teens assigned to usual care. Providing this type of brief intervention is a viable approach to working with high-risk teens to decrease substance use. © 2008 Published by Elsevier Inc. Keywords: Adolescents; Drug use and alcohol consumption; Motivational interviewing; Intervention; Primary care

1. Introduction A significant percentage of high-school-aged youth who consume alcohol and use drugs report enough problems from use to meet diagnostic criteria for a substance abuse disorder (14% and 23% in Grades 9 and 12, respectively; Dukes, Marinex, & Stein, 1997). Many of these teens may then go on to have a substance abuse or substance dependence disorder in late young adulthood (D'Amico, Elickson, Collins, Martino, & Klein, 2005]), which substantially increases the risk of having a substance use disorder in later life (Helzer, Burnam, & McEvoy, 1991). Thus, it is crucial to intervene with this age group because decreasing substance use during the teen years can reduce the chances of later problems in young adulthood and adulthood. Most teens, however, do not seek help for substance use due to stigma (Corrigan, 2004), fears about confidentiality

⁎ Corresponding author. RAND Corporation, Santa Monica, CA 904072138, USA. Tel.: +1 310 393 0411x6487; fax: +1 310 260 8150. E-mail address: elizabeth_d'[email protected] (E.J. D'Amico). 0740-5472/08/$ – see front matter © 2008 Published by Elsevier Inc. doi:10.1016/j.jsat.2007.08.008

(Dubow, Lovko, & Kausch, 1990), or inability to relate to the person implementing the service (D'Amico, 2005). It is therefore important to provide services that are developmentally relevant and easily accessible to youth. For example, teens tend to respond more positively to a motivational approach (Brown, 2001; D'Amico, Elickson, Wagner, et al., 2005; Masterman & Kelly, 2003). This approach emphasizes an interactive process in which people are active participants (Miller & Rollnick, 2002), thus increasing the probability that the intervention is acceptable to adolescents (D'Amico & Edelen, in press; Masterman & Kelly, 2003; Tevyaw & Monti, 2004). In terms of access, the primary care (PC) setting presents a unique opportunity to intervene with substance-abusing adolescents as 62% of 14- to 17-year-old youth visit a physician at least once a year and 83% of youth from this age group are seen at least once over a 2-year period (O'Connor, Hollis, Polen, & Lichtenstein, 1999). In addition, PC lends itself to discussing sensitive information, and most adolescents report a desire to discuss drug use and smoking with their PC provider if they are assured of confidentiality (Ford, Millstein, Halpern-Felsher, & Irwin, 1997).

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A number of studies have demonstrated the effectiveness of screening for alcohol problems and delivering brief interventions for adult problem drinkers in PC settings (Fleming, Barry, Manwell, & Johnson, 1997; Kaner et al., 2007; Ockene, Adams, Hurley, Wheeler, & Herbert, 1999). More recently, clinicians and researchers have begun to test the potential effectiveness of brief interventions for adolescents that may well be suited to PC settings. For example, Colby et al. (2005) and Monti et al. (1999) have developed and tested brief motivational interventions for alcohol and smoking in hospital and clinic settings with successful results. One brief motivational intervention targeted older adolescents (18 and 19 years of age) who were treated in the emergency room (ER) for an alcoholrelated injury. Participants received either a brief motivational intervention for approximately 45 minutes or standard care (Barnett, Monti, & Wood, 2001; Monti et al., 1999). Findings indicated that teens who received the motivational intervention were less likely to report driving after drinking and alcohol-related problems than those who received standard care at a 6-month follow-up (Monti et al., 1999). Of note, this intervention took place in a hospital ER setting and targeted teens who had experienced a traumatic event, such as an alcohol-related injury and did not therefore take place as part of a regular PC appointment. Another study evaluated the efficacy of a brief motivational intervention for teen smokers (Colby et al., 2005). Teen patients were recruited from an emergency department and an adolescent outpatient clinic and were either assigned to a brief motivational intervention (35 minutes plus a 15- to 20-minute booster 1 month later) or subjected to brief advice (5 minutes). Both groups showed reduced cotinine levels at 6 months; however, no differences were found between the groups (Colby et al., 2005). Knight et al. (2005) recently examined the potential of a motivational interviewing (MI) intervention for alcohol consumption and drug use in a PC setting. They screened patients, ages 14–18, from a medical practice and an adolescent substance abuse program at Children's Hospital in Boston. Eligible youth were invited to participate in the study at the conclusion of their clinic visit. Youth received two 60-minute sessions targeting alcohol consumption and drug use. The first MI session occurred 2 weeks after their clinic appointment and the second MI session occurred 2 weeks after the first MI session. This study did not have a comparison group of teens. As with many studies with highrisk teens, the authors had great difficulty with recruitment and attrition. Specifically, they were only able to recruit 33 adolescents over a 12-month period and only 22 teens completed the study. Despite these difficulties, at a 3-month follow-up, youth who completed the intervention reported reduced substance use and driving after drinking (Knight et al., 2005). This study addresses several gaps in the literature. First, we examined the efficacy of a 15-minute MI intervention for

high-risk youth that is delivered in a PC setting. Second, we randomized teens into an intervention group or to a “care as usual” control group. Third, our intervention targets both alcohol consumption and drug use and is designed to take place during a regular PC appointment. Project CHAT makes a unique contribution to the field because (a) it is delivered in a PC medical setting rather than in a school setting or an emergency department, (b) it requires only a single 15- to 20-minute session (relative to other interventions that take at least 45 minutes and multiple sessions), and (c) there are currently no brief MI interventions for teens in the PC setting that can be incorporated within the time frame of a typical PC appointment (Stern, Meredith, Gholson, Gore, & D'Amico, 2007). 2. Materials and methods 2.1. Sample and study site We recruited participants from a community-based health care clinic in Los Angeles County between June 2005 and December 2006. Our clinic partner was a community-based PC clinic in Los Angeles County that provides free care to underserved populations, described as the uninsured; the working poor; homeless, runaway, and high-risk youth; and others who are unable to access affordable health care and human services. Most of the clients are members of an ethnic minority group. Clinic statistics during the time this study took place indicated that of the 12- to 18-year-olds who attended the clinic, 61% were Hispanic, 13% were African American, and 12% were White. Fig. 1 provides a flowchart outlining the process by which participants were screened and enrolled. Adolescents were approached if they were between the ages of 12 and 18 (n = 724). Approximately 43% (n = 313) of those approached agreed to complete the anonymous screening questionnaire. Noncompletion of the screening questionnaire was mainly due to either the teen or the parent being non-English speaking (41%), hard refusal by the parent or teen (36%), or the teen being too busy (13%). Approximately 26% of screened youth (n = 81) were high risk and met our eligibility criteria (e.g., reported alcohol consumption and drug use and some consequences due to use; see Section 2.5). To participate, youth also had to be able to return to the clinic for a 15- to 20-minute appointment and had to be English speaking. Sixty-four adolescents enrolled in the study, and 42 of these youth completed the study. Youth ranged in age from 12 to 18; 48% were male, and 85.7% identified themselves as Hispanic or Latino, 9.5% as African American, and 4.8% as White (see Table 1). Of the 22 noncompleters, 16 were in the intervention group and 6 were in the control group. To maximize the utility of the limited resources available to the researchers, youth who failed to attend the intervention were considered to be dropouts. A teen was

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Fig. 1. Flowchart of participant enrollment.

dropped out of the study if he or she could no longer be reached (either due to a disconnected telephone connection or due to his or her having moved to a new address; n = 14) or if he or she no longer wanted to participate in the study (n = 8). 2.2. Procedure All materials and procedures were approved by RAND's Institutional Review Board and the community clinic. Each week, we were provided a schedule with appointment times

for teens between the ages of 12 and 18. No names were provided. A RAND staff member went to the clinic during heavily scheduled appointment times and approached teens to see if they met eligibility criteria; that is, participating teens had to be English speaking, 12–18 years of age, interested in our study, and willing to complete our anonymous screening questionnaire. Although all youth were required to be English speaking because the intervention was conducted in English, materials were provided in both English and Spanish for parents who spoke only Spanish and for those youth who felt more

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Table 1 Demographic characteristics of the total sample (N = 42) Demographics Age (years) 12 13 14 15 16 17 18 Gender Male Female Race/Ethnicity Hispanic or Latino African American White Living arrangement a With 2 parents With 1 parent With an adult other than a parent Mother's education b Completed high school Yes No Don't know Attended at least some college Yes No Don't know Reported last 30-day use Alcohol Marijuana Cigarettes Reported lifetime use Alcohol Marijuana Cigarettes

n

%

2 1 8 6 6 5 14

4.8 2.4 19.0 14.3 14.3 11.9 33.3

20 22

47.6 52.4

36 4 2

85.7 9.5 4.8

23 12 7

54.8 28.6 16.7

18 18 6

42.9 42.9 14.3

13 22 7

31.0 52.4 16.7

33 22 16

78.6 52.4 38.1

42 34 31

100.0 81.0 73.8

a In this case, “parent” could be any of the following: mother, father, stepmother, or stepfather. b Mother's education was chosen because teens did not typically know their father's education.

comfortable completing the measures in Spanish. Both parental consent and youth assent were obtained for those teens who completed the anonymous screener and were eligible for inclusion in the study. After obtaining consent, youth were randomly assigned to either the intervention (Project CHAT) group or the usual-care group. Initially, youth were randomized on a one-to-one basis; that is, the probability of being assigned to either group was equal. However, as the trial progressed, we recognized that dropout rates were unequal between the groups, with youth from the intervention group less likely to be followed up. Thus, to maximize power, we altered the allocation schedule such that the probability of being allocated to the intervention group was higher, and hence, 26 youth were assigned to the control group and 38 youth were assigned to the intervention group. All teens

completed a baseline survey in the clinic, sealed it in an envelope, and gave it to a RAND staff member, or they completed the survey at home and mailed the survey back to RAND. Youth in both conditions were sent follow-up mail questionnaires (3 months after completion of baseline for the control group and 3 months after the intervention for the intervention group) and returned the questionnaire in a postage-paid envelope to RAND. Youth received US$15 for the baseline survey and US$25 for the 3-month survey. Youth who completed Project CHAT received US$15. During the study, we increased the incentive for the intervention to US$30 to encourage more teens to complete the study. Eight of the 22 teens received this amount. 2.3. Project CHAT intervention Teens assigned to Project CHAT received a 15- to 20-minute MI intervention after completing their baseline survey. Most teens (68%) received Project CHAT within 3 weeks after completion of the baseline survey. We also provided a 5- to 10-minute booster telephone call 1 month after they completed Project CHAT. Up to five call attempts were made to reach teens over a 2-week period. If teens could not be reached during this period, then they did not receive the booster. Eleven of 22 teens received the booster call. We trained case managers at the clinic on Project CHAT who worked in the mental health division of the clinic (see Section 2.4). Due to staff turnover, four different case managers delivered Project CHAT during the study period. Two case managers had an associate degree and two had a master's degree. Briefly, the session focused on assessing motivation to change (5–7 minutes), enhancing motivation for change (5–7 minutes), and making a plan (5–7 minutes). The booster call briefly reiterated what the teen had discussed in the Project CHAT session, reviewed their goals and whether they had been able to implement any of the strategies they had discussed during the session, and revised goals as necessary. Project CHAT is described more fully elsewhere (Stern et al., 2007). 2.4. Training and fidelity For the current study, the first author (E.D.), a licensed clinical psychologist, was the lead study trainer. E.D. is also certified as one of the Motivational Interviewing Network of Trainers (MINT). MINT membership is limited to trainers who have completed a training workshop for new MI trainers recognized by the MINT to encourage good practice standards. During the study, the training for each interventionist consisted of an overview of MI, a thorough review of the 15-minute protocol, and several practice role-play sessions of different scenarios that the interventionist might encounter. The role plays were based on data from previous adolescent tapes from our pilot study (Stern et al., 2007) so that the scenarios were realistic. Throughout the study, E.D.

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listened to every audiotape for fidelity to both MI and the protocol. After every intervention session, E.D. provided supervision to the interventionist to discuss the session, address questions and concerns, and discuss the interventionist's overall adherence to both MI and the protocol for that session. This is consistent with the recommendation of Miller, Yahne, Moyers, Martinez, and Pirritano (2004) to provide coaching and feedback to clinicians who are learning MI as this type of supervision was most effective in increasing posttraining proficiency. In addition, at the end of each session, teens rated their satisfaction with the intervention (e.g., found discussion and interventionist helpful) and the interventionist's adherence to the protocol from 1 (completely satisfied/covered) to 5 (not at all satisfied/covered). Mean ratings for satisfaction ranged from 1.30 to 2.0, indicating that teens found the discussion (M = 2.0) and interventionist (M = 1.30) helpful, liked the style of the meeting (M = 1.65), and could use the information (M = 2.0). Mean ratings on adherence were high and ranged from 1.35 to 1.43, indicating that specific content that was supposed to be discussed was talked about during the session (e.g., discussed a plan in case the participant wants to make a change in his or her alcohol consumption or drug use). 2.5. Measures 2.5.1. Screener The CRAFFT was developed by Knight et al. (1999) to screen youth for alcohol consumption and other drug use and is a mnemonic based on its six yes/no questions: (a) Have you ever ridden in a Car driven by someone (including yourself) who was high or had been using alcohol or drugs? (b) Do you ever use alcohol or drugs to Relax, feel better about yourself, or fit in? (c) Do you ever use alcohol or drugs while you are by yourself (Alone)? (d) Do you ever Forget things you did while using alcohol or drugs? (e) Do your family and Friends ever tell you that you should cut down on your drinking or drug use? (f) Have you ever gotten into Trouble while you were using alcohol or drugs? To qualify for the current study, we used a cutoff score of 1 to include adolescents with potential problems who could benefit from a brief intervention in the PC setting. However, if teens endorsed “Have you ever ridden in a car driven by someone (including yourself) who was high or had been using alcohol or drugs?” they had to answer yes to one additional CRAFFT question. Our screener questionnaire also included six filler questions so that recruitment criteria were less evident, such as “Do you generally feel confident and relaxed in social situations?” and “In the past week, have you watched any television programs where people used drugs other than alcohol (e.g., marijuana, cocaine)?” Of the 81 teens who were screened for the study, 27% answered yes to one screening question, 19% answered yes to two questions, and 53% answered

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yes to three or more questions. The following were the most frequently endorsed questions: “used alcohol or drugs to relax,” “got into trouble while using,” and “family/friends tell you to cut down.” 2.5.2. Survey 2.5.2.1. Background questions. Background questions included age, gender, ethnicity, grades received in school, number of grades repeated, number of schools attended during the elementary and middle school years, family education, and living situation. 2.5.2.2. Peer influence. Youth were asked several questions to address peer influence. They were asked single items about how often they spent time around teens who drank alcohol or used marijuana (1 = never to 4 = often; Tucker, Orlando, & Ellickson, 2003). Participants estimated the percentage of students in their grade who drank alcohol and smoked marijuana (WestEd., 2005). Responses were made using an 11-point response format, ranging from none (0%) to all (100%), with each point reflecting 10 percentage points. We also assessed friends' consumption of alcoholic beverages and use of marijuana with two items from Monitoring the Future (0 = none to 4 = all; Johnston, O'Malley, Bachman, & Schulenberg, 2007). 2.5.2.3. Intentions to use. Separate single items from the RAND Adolescent/Young Adult Panel Survey (Tucker et al., 2003) assessed whether teens thought they would consume alcohol or use marijuana in the next 6 months (1 = definitely no to 4 = definitely yes). 2.5.2.4. Alcohol consumption and marijuana use. We measured alcohol consumption and marijuana use with parallel items from the RAND Adolescent/Young Adult Panel Survey (Tucker et al., 2003). Single items asked the number of days in the last month youth drank alcohol or used marijuana (on a Likert scale from 0 [none] to 5 [10 or more days]), the number of times they used marijuana (once a day to three times a day or more) on the days they used the substance, the number of alcoholic drinks they consumed (a few sips to three or more drinks) on the days they drank alcohol, and the number of days in the last month they consumed three or more alcoholic drinks (none to more than 8 days). 2.5.2.5. Consequences. Two sets of questions based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria assessed whether adolescents had experienced consequences due to their alcohol consumption (e.g., missed school or work) or marijuana use (e.g., got into trouble at school or home) in the past year (Tucker et al., 2003). Scales ranged from 0 (none) to 2 (two or more times; α = .76 for marijuana and α = .77 for alcohol in the current study).

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2.5.2.6. Social desirability. We measured social desirability with the social desirability response scale (Hays, Hayashi, & Stewart, 1989; e.g., I am always courteous even to people who are disagreeable). Responses ranged from definitely true to definitely false (α = .61).

based on the difference found in the analysis of covariance and a pooled standard deviation estimate. Finally, we examined the effect of receiving the booster telephone call by comparing teens in the intervention group who received the call with teens who did not receive the call, using the same procedures used for the evaluation of the intervention.

3. Results

3.2. Attrition

3.1. Overview of analyses

The baseline measure of each outcome, age, gender, and treatment group were used as predictors of completion of follow-up. Three measures were significant predictors of follow-up. The number of days that teens consumed three or more drinks (odds ratio [OR] = 0.51, 95% confidence interval [CI] = 0.32–0.80; p = .002) and the number of days they consumed any alcohol in the last month (OR = 0.63, 95% CI = 0.43–0.92; p = .019) were both significant predictors of follow-up, with higher consumption indicating lower compliance. Although this marginally failed to achieve statistical significance, teens in the intervention group were less likely to be followed up compared to teens in the control group (61% of teens in the intervention group; 83% of teens in the control group; OR = 0.31, 95% CI = 0.09–1.11; p = .059). No demographic measures were significantly associated with completion rates.

We first used logistic regression to explore baseline predictors of completion and dropout in unifactorial analyses. We examined baseline measures of outcome variables, age, gender, intervention group, and ethnicity (Hispanic vs. not Hispanic) as potential predictors of dropout. We next used analysis of covariance to examine the effect of the intervention versus control. In each case, the baseline measure of the outcome variable was employed as a covariate, along with age, gender, and baseline scores of social desirability. For variables with smaller numbers of categories, or where the distribution seemed to depart from normality, we also carried out ordinal logistic regression. As these analyses did not alter our substantive conclusions, we do not report them. Due to the problem of nonrandom failure to follow up, we carried out a sensitivity analysis using expectation maximization parameter estimates to make use of partially complete data, as implemented in Mplus 4.2 (Muthén & Muthén, 2007). This allowed us to make the assumption that the data were missing at random (Schafer & Graham, 2002) and avoid problems with biases that may occur with nonrandom follow-up. These results were not substantively or meaningfully different from the complete case analysis, and hence, we have only reported the complete case results. To ease interpretation of our effects, we calculated a standardized effect size (ES; Cohen's d; Cohen, 1992)

3.3. Effects of Project CHAT For each outcome of interest, we used analysis of covariance to examine the effect of the intervention (Table 2). Outcome effects were in the predicted direction for all dependent variables, with the exception of alcohol consequences, which had a small nonsignificant effect in the opposite direction (estimate = 0.04, ES = .07). Four outcomes achieved statistical significance (at the conventional p ≤ .05 level). Youth in Project CHAT were less likely to report intentions to use marijuana (ES = .86) in the next

Table 2 Effects of Project CHAT intervention on all outcome variables Outcome Alcohol Intentions Perceived prevalence Number of friends who consume How often with teens who consume Consequences No. of days consumed (last month) How many drinks consumed Number of days consumed 3+ drinks Marijuana Intentions Perceived prevalence Number of friends who use How often with teens who use Consequences No. of days used (last month) How many times used

Estimate of effect of intervention

SE

p

Lower 95% CI

Upper 95% CI

Standardized ES

−0.62 −1.39 −0.37 −0.39 0.04 −0.80 −0.18 −0.22

0.34 0.75 0.30 0.28 0.14 0.63 0.42 0.35

.074 .073 .223 .171 .801 .210 .675 .542

−1.30 −2.92 −0.97 −0.95 −0.25 −2.07 −1.03 −0.93

0.06 0.14 0.23 0.18 0.33 0.47 0.67 0.50

.62 .47 .34 .40 .07 .43 .11 .20

−0.97 −2.27 −0.66 −0.53 −0.22 −0.84 −0.76

0.32 0.75 0.26 0.33 0.19 0.56 0.26

.004 .004 .016 .114 .257 .142 .005

−1.61 −3.78 −1.18 −1.19 −0.60 −1.97 −1.27

−0.33 −0.75 −0.13 0.13 0.17 0.29 −0.24

.86 .79 .61 .49 .31 .45 .79

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Fig. 2. Effects of Project CHAT intervention on perceived prevalence for alcohol and marijuana.

6 months, as compared to youth in the control group. In addition, Project CHAT teens reported lower perceived prevalence of marijuana use (Fig. 2; ES = .79) and fewer friends who used marijuana than teens in the control group (ES = .61). Project CHAT teens also reported using marijuana fewer times on the days they used, as compared to teens in the control group (Fig. 3; ES = .79). Using Cohen's d (Cohen, 1992), ESs were calculated for each outcome variable to determine the clinical significance of current results (see Table 2). For all outcomes of interest, ESs in favor of the intervention ranged from .11 to .86, with half of the ES in the medium-to-large range. This is notable because the current sample size was small. Thus, for some of the statistically nonsignificant results, such as number of friends who consume alcohol (ES = .34), how often around teens who use marijuana (ES = .49), and marijuana consequences (ES = .31), one can see that with a slightly larger sample, it would be possible to achieve statistically significant effects for these outcomes (assuming that the magnitude of the effect is unchanged). 3.4. Booster call

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estimates of marijuana use. ESs were large for the marijuana variables and in the small-to-medium range for many of the alcohol outcome variables, although alcohol outcomes were not statistically significant. This emphasizes the clinical significance of this intervention and suggests that this type of brief MI intervention can be effective in reducing substance use among high-risk teens. Reaching high-risk teens is often difficult. Project CHAT is a promising approach because it requires only 15–20 minutes and can therefore be provided within the context of an already scheduled PC appointment. PC providers could easily designate staff to screen adolescents, and those who report high-risk substance use could be referred to Project CHAT right after their PC appointment. In the current study, teens in the intervention group had to return to the clinic one extra time for their appointment, which decreased our retention rates for this group. Although we provided transportation costs and scheduled the appointment at a time that is convenient for the teen, many did not return due to difficulty with transportation back to the clinic (e.g., teens had to depend on their parents), their being very busy (e.g., school activities during clinic hours), or loss of communication (e.g., their telephone line had been disconnected or they had moved). Thus, it seems important to implement the intervention on the same day that the teen is seen at the clinic for his or her PC appointment. This would require having someone available in the setting who is trained to provide this service. In the current clinic setting, this was not an issue because case managers were available to provide services. In other PC settings, it would be important to train staff, such as nurses, interns, or mental health specialists, so that the teens could be seen immediately following their appointment with their PC provider. Of note, due to turnover rates in staff during the study period, we trained four different people to implement the intervention, all of whom had an associate or a master's degree with different educational backgrounds. Despite this difficulty, the intervention still had a significant impact on marijuana use rates, and many ESs for statistically nonsignificant outcomes were in the medium range. This highlights the transferability of this intervention to different PC settings as it is possible to successfully train staff with

We examined the effect of the booster call by comparing teens in the intervention group who received the booster with those who had not received the booster. In each analysis, the baseline measure of the outcome variable was employed as a covariate. No statistically significant effects were found for any of the outcome variables. 4. Discussion The current study provides preliminary evidence that a brief MI intervention for high-risk teens in PC can significantly impact marijuana use, intentions to use marijuana, number of friends who use marijuana, and prevalence

Fig. 3. Effects of Project CHAT intervention on the number of times teens used marijuana.

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different educational backgrounds on MI and the brief Project CHAT protocol. We also contended with many unique circumstances in this clinic setting that affected our enrollment and retention rates. For example, many patients were recent immigrants (e.g., from Mexico, Russia, and Korea) visiting this clinic for vaccinations. Because this small pilot study only offered the intervention in English, we could not include them in the study. In addition, this health care setting served a predominantly poor and minority population and faced a number of challenges not typical in other PC settings, including numerous patients not showing for scheduled appointments and many patients reporting lack of transportation (Stern et al., 2007). This made it difficult to contact many teens after their initial appointment. We used standard follow-up procedures, such as calling other contacts that teens listed and driving to homes to drop off survey materials. In some cases, teens left their homes without telling their parents or they moved to another state so that they could not attend the intervention. Despite these difficulties, our sample comprised a large percentage of minority youth (95%) and represents the clinic population. Our retention rates are also similar to other intervention studies with high-risk teens (Knight et al., 2005). Of note, 45% of eligible teens were 17– 18 years old. This is not unusual as use rates and consequences typically increase with age (Johnston et al., 2007); however, it suggests that targeting an older age range in this setting may increase the likelihood of reaching more teens at high risk for substance use consequences. Due to difficulty in reaching teens, only 11 of 22 teens received the booster telephone call. However, results did not differ for those who received the booster versus those who did not receive the booster. Finally, teens who completed the study versus those who did not complete the study were also less likely to report heavy drinking, which may have affected our ability to detect statistically significant effects on the alcohol outcome variables. ESs indicate, however, that with slightly larger samples, the intervention may have also decreased heavy drinking, given that the effects remained constant. This small pilot study is the first step in a program of research to bring brief MI interventions to high-risk teens during a regularly scheduled PC appointment. Findings suggest that Project CHAT is effective in reducing marijuana use. Due to the preliminary nature of this work and the limitations due to enrollment and attrition, further research is warranted. However, current results are promising and the ESs generated from this study are crucial to help plan a larger test of Project CHAT in other PC settings with bigger samples and examination of long-term outcomes. Acknowledgments Work on this article was supported by a grant from the National Institute on Drug Abuse (R21DA018854) to Elizabeth J. D'Amico. We wish to thank the adolescents,

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