Evaluation of assessment instruments for working alliance in psychological interventions with adolescents: A...

The working alliance is one of the most robust predictors of outcomes in adult psychotherapy. Since the alliance is often challenging to establish and maintain in psychotherapy with adolescents, conducting high-quality assessments of the alliance using sound measures in this population is critical. Still, measurement instruments developed for adults cannot be directly transferred to adolescent samples. This systematic review aimed to identify and critically evaluate available assessment tools for working alliance in adolescent psychotherapy using the COnsensus-based Standards for the Selection of Health Measurement INstruments (COSMIN) framework. A comprehensive literature search across PsycINFO, PubMed, Web of Science, and PsycARTICLES, up to October 2024, yielded 47 research studies reporting on working alliance measurement properties. Findings indicate that self-report measures are most commonly studied, with the Working Alliance Inventory-Short Form (WAI-S) and Therapeutic Alliance Quality Scale (TAQS) showing the best psychometric properties. Nevertheless, even with these measures, there are notable shortcomings in cross-cultural validity, measurement error, and responsiveness, which are essential for applications in longitudinal studies and with diverse populations. Less commonly studied, often with very small samples, observer-rated tools displayed high reliability but limited predictive validity. Our review highlights the need for more stringent research on developmentally appropriate, reliable working alliance instruments for adolescents to support clinicians and researchers in studying and monitoring this aspect of patient-therapist relations. These findings, together with the COSMIN guidelines, inform recommendations for future research mainly in terms of improved content validity, measurement error, cross-cultural validity, and responsiveness.