Validation of two informant-based screening instruments for personality disorders in a psychiatric outpatient population

Abstract

Purpose: The predictive validity of two informant-based screening instruments for personality disorders (PDs), the Standardized Assessment of Personality (SAP) and a short eight-item version (SAPAS-INF), were studied in 103 Dutch psychiatric outpatients, using the SCID-II as the ‘gold standard’. Methods: All patients and their informants were interviewed separately and independently by different interviewers who were unaware of the results in the other conditions. Results: According to the SCID-II, 66 patients had at least one personality disorder (PD). The SAP correctly classified 72% of all participants in the category PD present/absent. The sensitivity and specificity were 69% and 76%, respectively. The positive and negative predictive values were 84% and 58%. The SAPAS-INF, using a cut-off score of 3, correctly classified 70%; the sensitivity and specificity were 76% and 58%, respectively. The positive and the negative predictive values were 77% and 57%. Conclusion: These results show that the informant-based SAP as well as the shorter informant-based SAPAS-INF are adequate; though rather moderate screening instruments for identifying PD. The SAP and the SAPAS-INF, however, both performed worse than the SAPAS-SR, which is based on the patient’s self-report. Therefore, it is concluded that the SAP or the SAPAS-INF can be used as a satisfactory screening instruments for the presence/absence of PD in those cases where patients themselves are unable to provide the required information.