Spanish Adaptation of the Working Alliance Inventory-Short (WAI-S)

The goal of our research was to adapt the short forms of the Working Alliance Inventory into the Spanish language for patients and therapists (WAI-S-P and WAI-S-T). The psychometric properties of scores from these measurement instruments were evaluated in Spanish outpatients with depressive disorders and their therapists. The scores of both measures exhibited excellent reliability in terms of internal consistency and excellent convergent validity. Their discriminant validity exhibited some limitations, particularly when the scores of both short measures correlated with those of two empathy measures. Regarding predictive validity, the scores of the overall WAI-S-P and WAI-S-T significantly correlated with residual gain scores of patients in the Beck Depression Inventory (BDI) after the tenth psychotherapy session. Additionally, the overall WAI-S-T scores explained a moderate percentage of the variance in patient BDI score changes. These results are satisfactory and similar to those found in the studies that have utilized the respective original versions of WAI-S in English.