Patient interpersonal factors and the therapeutic alliance in two treatments for bulimia nervosa.

Although the therapeutic alliance is robustly associated with psychotherapy outcomes, less is known about factors that influence its development. This study examined the association between baseline patient interpersonal factors and patient-rated alliance in a randomized trial comparing cognitive-behavioral therapy (CBT) and interpersonal therapy (IPT) for bulimia nervosa. Using hierarchical linear modeling, early and middle alliance were negatively associated with interpersonal distress and positively associated with interpersonal affiliation. Middle alliance was also related to treatment group interactions with rigidity, affiliation, and control. Overall, alliance growth was higher in IPT than CBT. Using group-based trajectory analysis, three divergent alliance trajectories emerged (high and improving, low and improving, and low and stable), with group mean differences between two of them in terms of interpersonal distress and hostile-submissiveness.