Reliability and validity of the Diagnostic Scales of the Schedule for Nonadaptive and Adaptive Personality-2 (SNAP-2) in Italian community-dwelling adults and psychiatric patients

To evaluate the psychometric properties of the Italian translation of the Schedule for Nonadaptive and Adaptive Personality-2 (SNAP-2) diagnostic scales, 837 Italian community-dwelling adults and 429 consecutively admitted Italian psychiatric adults were administered the SNAP-2. The 12 SNAP-2 diagnostic scales yielded reliable scores in both community (median ω value = .90) and psychiatric (median ω value = .92) samples. The 6-month temporal stability was adequate for all SNAP-2 diagnostic scales (median test-retest r-value = .84) in a subsample of the community-dwelling adults (n = 97). When we examined the correlations between the SNAP-2 diagnostic scales and the Five-Factor Model Rating Form trait scales among the community-dwelling adults, the double-entry intraclass correlation values (median ICCDE = .94) indicated a marked similarity between our correlation profiles and the correlation profiles that were reported in Samuel and Widiger (2008) meta-analysis. In our psychiatric-adult sample, the SNAP-2 diagnostic scales showed adequate convergent-validity coefficients (median r-value = .61) with criterion measures of DSM-IV axis II/DSM-5 Section II personality disorders (PDs). Finally, relative-weight analysis results showed that selected Personality Inventory for DSM-5 trait-scale scores explained a substantial amount of variance in SNAP-2 antisocial, avoidant, borderline, narcissistic, obsessive-compulsive, and schizotypal PD scale scores (median R 2 value = .55). As a whole, our data suggest that the Italian SNAP-2 diagnostic scales have adequate reliability and construct validity in the Italian culture. (PsycInfo Database Record (c) 2021 APA, all rights reserved).