Treatment fidelity in a multisite trial of Brief Strategic Family Therapy for adolescent drug abuse was poorest when youth had multiple arrests, high substance use, and high externalizing scores before treatment began. Research using fidelity ratings as a proxy independent variable should account for possible responsiveness related to case difficulty. The parent study compared BSFT to treatment as usual for substance-using adolescents in 8 community treatment programs, where volunteer clinicians randomly assigned to provide BSFT completed a training (certification) program before seeing cases in the clinical trial. The index adolescents were years old (M = 15.9), 79% male, 44% Hispanic, and 23% African-American. An expert panel rated treatment fidelity for 104 cases receiving at least 5 sessions of BSFT from one of 17 community therapists in NIDA CTN Protocol 014. The fidelity panel used session videos and progress notes from the first 4 months of therapy to generate case-level consensus ratings of formulation quality, intervention quality, off-model behavior, and over-all fidelity to the BSFT model. The panel also coded whether specific patterns of fidelity failure were present in each case. We used baseline data to construct indices of case difficulty representing both the severity of adolescent problem behavior and the quality of family functioning. Indicators of problem severity included (a) a composite measure of substance-use, which combined Timeline Follow-back self-reports and urine drug screens; (b) a composite measure of externalizing behavior, combining scores from the Youth Self Report (YSR), the DISC Predictive Scales (completed by the adolescent and one parent), and the Delinquency scale of the National Youth Survey (Feaster et al., 2010); and (c) a simple index of multiple prior arrests. Indicators of family functioning included (d) a self- report composite of the Family Environment Scale and Parenting Practices Questionnaire, completed by the adolescent and a parent (Feaster et al., 2010); and (e) observer ratings of the overall quality of family functioning during a structured family interaction task, based on the Global Assessment of Relational Functioning (GARF) scale (Dausch et al., 1996). Treatment fidelity (or integrity), defined as the extent to which a therapist faithfully implements manualized intervention procedures, is an increasingly important area in psychotherapy research (Perepletchickova et al., 2007). While most interest centers on associations between fidelity and outcome, recent studies of therapeutic “responsiveness” suggest that client characteristics such as problem severity or case difficulty might help to explain how competently a therapist applies a given manualized intervention (Schoenwald at el, 2003; Stiles et al., 1998). We investigated this possibility in a multisite trial of Brief Strategic Family Therapy (BSFT) for adolescent substance abuse. Does Case Difficulty Compromise the Fidelity of Family Therapy for Substance-Using Adolescents? Florencia Lebensohn-Chialvo a, Brant P. Hasler b, Michael J. Rohrbaugh a, Varda Shoham a a University of Arizona, b University of Pittsburgh NIDA Blending Conference, Albuquerque, NM, April 2010 The fidelity with which community therapists implemented a complex, manualized family therapy for adolescent substance users was responsive to case difficulty, with youth problem severity predicting compromised fidelity more than the quality of family interaction. In particular, youth with relatively severe externalizing problems appeared to “pull” specific kinds off-model therapist behavior, and this may imply directions for training (or inoculating) family therapists who work with this difficult population. Another implication is that research using treatment fidelity ratings as a proxy “independent” variable should account for possible responsiveness effects related to case difficulty. The study was supported by NIDA awards R01-DA , U10-DA15815, and U10-DA Dausch, B.M., Miklowitz,D.J., & Richards, J.A. (1996). Global Assessment of Relational Functioning Scale (GARF): II. Reliability and validity in a sample of bipolar patients. Family Process, 35, Feaster, D.J., Robbins, M.S., et al. (2010). Equivalence of family functioning and externalizing behaviors in adolescent substance users of different race/ethnicity. Journal of Substance Abuse Treatment, 38, S113-S124. Perepletchickova, F., Treat, T.A., & Kazdin, A.E. (2007). Treatment integrity in psychotherapy research: Analysis of the studies and examination of the associated factors. Journal of Consulting and Clinical Psychology, 75, Shoham, V., & Rohrbaugh, M.J. (2009, October). Elusive effects of Brief Strategic Family Therapy for adolescent drug abuse: Results from the CTN-014 mediator-moderator platform study. Steering committee of the Clinical Trials Network, National Institute on Drug Abuse, Bethesda, MD. Schoenwald, S.J., Halliday-Boykins, C.A., & Henggeler, S.W. (2003). Client-level predictors of adherence to MST in community service settings. Family Process, 42, Stiles, W. B., Honos-Webb, L., & Surko, M. (1998). Responsiveness in psychotherapy. Clinical Psychology: Science and Practice, 5, The modal quality of BSFT was less than ideal, as only a third of the TFS cases received what the expert panel considered “adequate” BSFT (fidelity > 3 on a 1-5 scale). As reported elsewhere, case-level fidelity correlated positively and often significantly with most outcomes at most follow-up intervals, with minority participants accounting for most of these associations (Shoham & Rohrbaugh, 2009). In the main regression analyses (Table 1), the three indicators of adolescent problem severity together accounted functioning did not (R 2 ∆ =.01). Youth externalizing problems predicted off- model therapist behavior most clearly, and the specific forms or a significant proportion of BSFT fidelity variance (R 2 ∆ =.10, p =.012) while the two measures of family of fidelity failure most implicated in this were therapist centrality (r =.39), didactic intervention style (r =.36), and non- systemic formulations (r =.33; all ps <.01). Correspondence: Florencia Lebensohn-Chialvo, Department of Psychology, University of Arizona, P.O. Box , Tucson, AZ California-Arizona Node, NIDA Clinical Trials Network U10 DA