The development of a brief personality scale to measure vulnerability to postnatal depression

Background: While a vulnerable personality style may increase the risk of developing non-psychotic and somatoform disorders, its measurement has been problematic. In this paper we describe the development of a 9-item Vulnerable Personality Style Questionnaire (VPSQ). Methods: The scale was administered to a randomly selected community sample and a sample of women who had given birth at Nepean Hospital. Principal components analyses was used to identify the underlying dimensions of the scale and to construct sub-scales. Scores on these sub-scales were compared between women diagnosed with postnatal depression (PND) and non-depressed women. Results: A principal components analysis of the VPSQ isolated two factors; labelled "vulnerability" and "organised/responsive" with similar results found in the separate samples. The instrument has good internal consistency (coefficient α = 0.63 for the whole scale, 0.77 for the "vulnerability" sub-scale and 0.18 for the "organised/responsive" sub-scale) and acceptable test-retest reliability. Significantly higher scores on the vulnerability sub-scale were found for women who were cases of postnatal depression compared to non-depressed women. The utility of the VPSQ as a brief, easily administered personality measure for early identification of those at risk of developing postnatal depression is discussed.