Development and psychometric evaluation of the Interactive Test of Interpersonal Behavior (ITIB): a pilot study examining interpersonal deficits in chronic depression.

Chronic depression is assumed to be caused and maintained by interpersonal deficits. We describe the development and psychometric evaluation of the Interactive Test of Interpersonal Behavior (ITIB) that we developed for self-assessment of these deficits. Participants with chronic depression (CD, N = 15), episodic depression (ED, N = 15) and healthy controls (HC, N = 15) participated in this pilot study. They completed the ITIB and a number of pen and paper questionnaires including the Lübeck Questionnaire of Preoperational Thinking (LQPT) and the inventory of interpersonal problems (IIP). The ITIB was highly acceptable for use in these participants. Internal consistency for the ITIB was adequate for group comparisons (Cronbach's alpha = 0.649). Item-total correlations indicated adequate discriminatory power of five of the six items. The ITIB correlated moderately with the LQPT (r = 0.524) and the IIP (r = -0.568). The ITIB score differed significantly between the diagnostic groups (ANOVA F(2,42) = 6.22, p = 0.004). It was the only measure that - albeit at a trend level - was associated with diagnostic group (CD vs. ED) on multinomial logistic regression analysis (B = 0.049 ± 0.029; OR 1.051; p = 0.088). We found preliminary evidence that the ITIB is an acceptable and psychometrically adequate measure of interpersonal behavior that distinguishes between patients with CD and patients with ED. If replicated with an improved version of the test, our results could support the hypothesis that having interpersonal problems is a core deficit in patients with CD.