A Second and Third Look at FIRST: Testing Adaptations of A Principle-Guided Youth Psychotherapy.

Objective: We examined the acceptability, integrity, and symptom trajectories associated with FIRST, a principle-guided treatment for youth internalizing and externalizing problems designed to support efficient uptake and implementation.Method: We conducted two open trials of an adapted FIRST, focusing on uptake and implementation by novice trainees in a university-affiliated clinic, limiting treatment duration to six sessions, and benchmarking findings against a 2017 FIRST trial with community therapists. In Study 1, trainees received a two-day training and weekly two-hour supervision (N = 22 youths, ages 7-17, 50% female, 54.54% Caucasian, 4.55% Latinx). In Study 2, trainees received a one-day training and weekly one-hour supervision, delivering the six-session FIRST in a predetermined sequence (N = 26 youths, ages 11-17, 42.31% female, 65.38% Caucasian, 7.69% Latinx). In Study 3, the original study therapists - now practitioners - evaluated FIRST's effectiveness and implementation difficulty, and reported their own post-study FIRST use.Results: Acceptability (treatment completion, session attendance, caregiver participation) and integrity (adherence, competence) were comparable across Study 1, Study 2 and the 2017 trial. Improvement effect sizes across ten outcome measures were in the large range in all three trials: M ES = 1.10 in the 2017 trial, 0.83 in Study 1, and 0.81 in Study 2. Study 3 showed high effectiveness ratings, low difficulty ratings, and continued use of FIRST by a majority of clinicians.Conclusions: Across two open trials and a follow-up survey, FIRST showed evidence of acceptability and integrity, with youth symptom reduction comparable to that in prior research.