Psychometric properties of the Brief Symptom Inventory-18 in a Spanish breast cancer sample.

Objective: The objective of this work was to study the psychometric and structural properties of the Brief Symptom Inventory-18 (BSI-18) in a sample of breast cancer patients (N=175).

Methods: Confirmatory factor analyses were conducted. Two models were tested: the theoretical model with the original structure (three-dimensional), and the empirical model (a four-factor structure) obtained through exploratory factor analysis initially performed by the authors of the BSI-18.