1. Scott E. Hadland MD MPH John R. Knight MD Sarah H. Copelas BA Sion K. Harris PhD

2.  Conflict of interest statement:  I have no commercial relationships to disclose  I will not be discussing any unapproved uses of pharmaceuticals or devices  Research supported by grant funding:  NIH/NIAAA(1R01AA021904, 1R34AA023026, 1R01AA02243)  NIH/NIDA (3U10DA013720-15S3)

3.  Understanding trajectories of teen substance use is critical for primary care physicians  Escalation of use influenced by parent, sibling and peer use  Studies to date have been school- or community-based  Trajectories of use among teens in primary care have not been well characterized L Chassin et al. J Abnorm Psychol, 2004;113(4):483-98 TE Duncan et al. Addiction, 1995;90(12):1647-60

4. 1.To identify and classify major substance use trajectories of adolescent primary care patients during the 12 months following a routine clinic visit 2.To identify the demographic and familial/peer substance use associated with different trajectory groups

5.  Adolescents recruited:  Quasi-experimental clinical trial 1  9 primary care urban, suburban, and rural practices in New England  12 to 18 year-olds presenting for routine primary care  Adolescents in the treatment-as-usual arm  Complete baseline and 12-month follow-up data 1 Harris SK, et al. Pediatrics, 2012;129(6):1072-1082.

6.  Assessed days of substance use in past 90 days at baseline and12-month follow-up  Used Modified Timeline Followback (TLFB) calendar-based interview  Conducted hierarchical cluster analysis to inform generation of clinically meaningful trajectories, using cutoffs of:  < monthly (< 3 of 90 days) vs. ≥ monthly use (≥ 3 of 90 days)  < weekly (< 12 of 90 days) vs. ≥ weekly use (≥ 12 of 90 days)

7.  Examined parent, sibling, peer substance use exposure using items from the Personal Experience Inventory  Affirmative if answered “agree”/”strongly agree” to any item  Parent use (4 items), e.g., “I have a parent whose use of alcohol or other drugs worries me”  Sibling use (4 items), e.g., “I have a brother or a sister who gets drunk or high”  Peer use (5 items), e.g., “Some kids I hang around with have trouble at school due to using alcohol or drugs”  Related parent, sibling and peer substance use to trajectory group membership using logistic regression GA Henly, KC Winters. Int J Addict, 1989;24(10):973-1001 KC Winters et al. Exp Clin Psychopharmacol, 2004;12(4):227-236

8.  Among adolescents included in sample:  61% were female  66% were white non-Hispanic  Mean age 15.4 years (SD, 2.0 years)

9.  Past 90-day use of alcohol or drugs:  23% at baseline  28% at 12-month follow-up  High rates of using both alcohol and drugs, so examined overall substance use days rather than alcohol and drugs separately

10. Abstained from use n=576 (60%) 0 days  0 days Initiated low-level use n=38 (4%) 0 day  1 day Ceased use n=57 (14%) 3 days  0 days Rapidly escalated n=82 (10%) 0 days  6 days Continued low-level use n=19 (2%) 1 day  1 day Continued heavy use n=46 (5%) 7.5 days  22.5 days Reduced heavy use n=42 (5%) 12.5 days  3 days

11.  Odds ratios [OR] for remaining abstinent during follow- up year (adjusted for gender, age):  Parents, OR = 0.59 (95% CI: 0.48 – 0.72)  Siblings, OR = 0.47 (95% CI: 0.39 – 0.55)  Peers, OR = 0.43 (95% CI: 0.35 – 0.52) Characteristic % of youth abstinent at baseline (N = 860) AbstainedDid not abstainp value Female61% 0.887 Age Group 12-14 yrs46%11%<0.001 15-16 yrs32%28% 17-18 yrs22%61%

12.  Odds ratios for “ceasing” use during follow-up (adjusted for gender, age):  Peers, OR = 0.45 (95% CI: 0.28 – 0.71)  Not significant: Parents, OR = 0.92 (95% CI: 0.66 – 1.26)  Not significant: Siblings, OR = 0.88 (95% CI: 0.68 – 1.12) Characteristic % of youth using at baseline (n = 198) CeasedDid not ceasep value Female70%62%0.260 Age Group 12-14 yrs12%6%0.204 15-16 yrs30%26% 17-18 yrs58%68%

13.  Odds ratios for rapidly escalating use (adjusted for gender, age):  Siblings, OR = 1.68 (95% CI: 1.35 – 2.08)  Peers, OR = 2.15 (95% CI: 1.55 – 2.98)  Not significant: Parents, OR = 1.22 (95% CI: 0.92 – 1.62) Characteristic % of abstinent / low-level users (n = 772) EscalatedDid not escalatep value Female57%61%0.468 Age Group 12-14 yrs10%41%<0.001 15-16 yrs24%32% 17-18 yrs66%27%

14. 1.A majority of teen primary care patients remained infrequent users or non-users over one year 2.Teens who abstained from use were less likely to report exposure to use by parents, siblings and peers 3.Teens who ceased use were less likely to report exposure to use by peers 4.Rapid escalators were more likely to be older youth who reported exposure to use by siblings and peers

15.  Strengths:  Longitudinal study of adolescents in primary care  Identified high risk subgroups and contributing risk factors  Potential Limitations:  Data collection relied on self-report  Sample drawn from New England; generalizability to other populations unknown  Highest-risk patients lost to follow-up

16.  Parent, sibling and peer substance use are increasing the risk of teen substance use  Therefore, providers should ask about substance use by parents, siblings and peers to understand their patients’ likely trajectories of use

17.  We thank the study participants for their contribution to the research, as well as current and past researchers and staff