In both adult and youth psychotherapy, the therapeutic alliance is considered to play an important role in therapeutic progress and treatment success. Recent meta-analyses among adults and youths found consistent, albeit moderate, associations between a strong therapeutic alliance and beneficial outcomes in mental health treatment (2–4). In the past decades, researchers have developed and adapted a wide range of instruments to assess the alliance, including versions for patients, therapists, parents and observers. Thus, the Working Alliance Inventory (WAI; Horvath and Greenberg, 1989) is the most extensively used questionnaire to assess therapeutic alliance. Specifically, more than two-thirds of the studies in the meta-analysis by Flückiger et al. (2) on adult psychotherapy used a version or adaptation of the WAI and in both meta-analyses on youth psychotherapy (3, 4) the WAI was also the most frequently used measure.
The WAI and its short forms the WAI-Short (WAI-S) (6) and WAI-Short Revised (WAI-SR) (7) are based on Bordin’s (1) conceptual model of the therapeutic alliance or 'working alliance'. Bordin (1, 8) describes the working alliance as the collaborative relationship between patient and therapist based on purposeful collaboration and an affective bond. Elements of the working alliance are the extent to which the patient-therapist dyad engages in purposeful collaboration, including the explicit negotiation of therapeutic tasks and goals, as well as the development of a sufficiently strong affective bond to engage in the therapeutic work during different treatment phases. In line with Bordin’s conceptualization, the working alliance is operationalized as a three-dimensional construct which incorporates the level of task collaboration (task), the degree of agreement on the treatment goals (goal) and the affective quality of the client-therapist relationship (bond). Both the WAI and WAI-S(R) are based on this three-dimensional structure with items that fall into a total scale and three subscales, i.e. task, goal and bond.
In adult populations the WAI has shown good internal, inter-rater and test-retest reliability indices (9) but empirical evidence for its underlying three-dimensional factor structure has been mixed. Some studies confirmed the 3-factor structure (5–7, 10, 11) whereas other studies demonstrated a 2- or single factor structure (12–15). Moreover, inter-correlations between the three subscales were high, especially the task and goal scale were highly correlated. More moderate correlations between the task and goal scales and improved model fit were found for the WAI-SR, the revised version of the WAI-S with negatively worded items excluded (7).
Distinguishing these different components of alliance has implications for research and practice. Some alliance studies focus primarily on the different components of alliance to determine which component has the highest priority at which stage of treatment (14, 15), while others see the value of alliance primarily as synergy of the different dimensions (5). According to Bordin (1) the demands placed on the different alliance dimensions differ by type of treatment. For example, cognitive behavioral therapy may focus more on collaboration (1, 14, 16–18) while interpersonal and humanistic therapies might place a greater emphasis on the bond (1, 14, 17). Although it is plausible that different types of treatments require different alliance `profiles`, most psychometric studies of the WAI do not differentiate between the specific alliance dimensions, especially in youth psychotherapy.
Although the WAI was originally designed for adult treatment and then adapted for use with children and adolescents (19, 20), its factor structure has not received much attention in the youth alliance literature. More research on this topic is particularly important since youth in psychotherapy may have a different understanding of the therapeutic alliance than adults. Some researchers propose that youth may view the alliance more as an affective instead of a cognitive construct (21). Others suggest that young people do not yet fully possess the cognitive skills needed to reflect on their own behavior and emotions, to formulate long-term treatment goals, to convert these abstract goals into specific tasks and to distinguish between treatment goals and tasks (19, 22, 23). Furthermore, it can be difficult to agree on treatment goals with young people who are often referred to treatment because of concerned parents or significant others, when they themselves may not recognize the symptoms of mental illness (24). Finally, typical characteristics of adolescents' developmental stage, such as the strong aspiration for independence and self-determination, may affect the formation of an affective and collaborative relationship between adolescents and their therapist (25, 26). In sum, due to (developmental) differences youth may experience the therapeutic alliance differently compared to adults which may imply that Bordin’s three-dimensional alliance model and the related factor structure of the WAI do not adequately reflect alliance in youth.
The few studies that have examined the factor structure of versions of the WAI questionnaire in youth have shown inconsistent findings and do not allow definite conclusions about the dimensional structure of the WAI in youth. The original WAI (5), with 36 items for both the patient and therapist version, was first investigated by DiGiuseppe et al. (19) among youth in psychotherapy. Their factor analysis yielded one single alliance factor for youth while for therapists besides the one single alliance factor the three factors for goal, task and bond were found. In addition, Diamond et al.(27) found a single alliance factor structure for both the therapist- and youth-rated WAI among patients in cannabis youth treatment (27).
The 12-item WAI-S (6), a shorter version of the WAI, was investigated in two youth studies showing a single factor solution for the client version in youths receiving treatment for anxiety (28) or depression (29). Although findings from Cirasola et al. (29) also provide some support for a two-factor alliance structure with collaboration (goal and task combined) and bond, the correlation between these two factors was very high (r = 0.91). Regarding the therapist version of the WAI-S, Cirasola et al. (29) demonstrated the best fit for the two-factor model and some evidence for the three-factor model. Unfortunately, factor analytic studies on the WAI-SR, the most refined version of the WAI, are lacking in youth.
Overall, prior studies on the factor structure of the WAI and WAI-S in youth treatment provide most empirical support for the general one-factor alliance model for both the youth and therapist versions. These results may indicate that the alliance structure is different in youth than in adults, but may also be explained by methodological limitations and the type of questionnaire that was investigated. A major limitation of previous studies is the lack of attention to the hierarchical ordering of the data, which may have led to biased parameter estimates, incorrectly and usually overestimated standard errors, and incorrect model fitting (30–34). Therefore, the use of multilevel confirmatory factor analyses (MCFA) to account for hierarchical data would be more appropriate for alliance data than the traditional confirmatory analyses.
Another explanation for previous findings may be the version of the WAI that was investigated. Both the WAI and WAI-S contained negatively worded items that could result in response bias among youth, a method effect found by Cirasola et al. (29). These earlier versions of the WAI may not be able to discern the different dimensions of the alliance in adolescents, whereas the WAI-SR may be more apt to identify the three-dimensional structure of the therapeutic alliance in adolescents.
In sum, therapeutic alliance is considered to play an important role in youth treatment and the emphasis on the three different alliance dimensions may vary by treatment type. To date, most psychometric studies that examined the factor structure of the WAI did not distinguish the three alliance dimensions but provided strongest support for a one-dimensional structure. These findings may indicate that the true alliance structure in youth consists of one general alliance dimension but may also be explained by methodological shortcomings, since most studies did not account for the clustering of the alliance data and examined WAI versions with negatively worded items which may lead to response bias.
In the present study we aim to address previous methodological limitations of psychometric studies on the WAI in youth by testing the factor structure of the latest adapted version of the WAI to avoid possible bias from negative items and by applying multilevel confirmatory factor analysis to account for clustered data. The main objective of the present study is to examine the psychometric properties of the WAI-SR in youth mental health and addiction treatment by (1) investigating whether the three-dimensional (task, goal and bond), or a one- or two-factor model of alliance adequately fits the construct of alliance in youth treatment; (2) examining whether the alliance structure is robust (a) across youths and therapists and (b) across time; and (3) taking into account the nested data structure, in which youth are nested in therapists.