Psychometric properties of the Brief Symptom Inventory support the hypothesis of a general psychopathological factor

The existence of a general factor related to psychiatric symptoms is supported by studies using a variety of methods in both clinical and non-clinical samples.

This study aims to evaluate the replicability of the internal structure of the Brief Symptom Inventory in a large Brazilian sample.

Participants were 6,427 Brazilian subjects (81% female). Mean age was 42.1 years (standard deviation [SD] = 13.6, Min = 13, Max = 80). All participants completed the online version of the Brief Symptom Inventory. This scale presents a general score (GSI) and nine specific clusters of symptoms (depression, anxiety, phobic anxiety, interpersonal sensibility, psychoticism, paranoid ideation, obsessive-compulsive behavior, hostility, and somatization symptoms).

Confirmatory factor analysis was performed to assess the factor structure of the BSI. The results showed that the best-fitting model was a bifactor solution and the general factor was the main dimension explaining most of the reliable variability in the data.

The findings suggest that the BSI's internal structure was replicated in a non-clinical sample and that the general factor is the most reliable score. However, it is necessary to better understand the meaning of the general factor scores in a non-clinical sample to increase interpretability of scores.