A mathematical typology analysis of DSM-III-R personality disorder classification: Grade of membership technique

This study employed grade of membership (GoM) analysis in a clinical setting to determine if the DSM-III-R personality disorder (PD) diagnostic criteria cluster into recognizable disorders resembling the official axis II nosology. The GoM model, based on fuzzy-set theoretic concepts, explicitly examines medical diagnostic systems by quantitatively identifying and characterizing subpatterns of illness within a broad class. A semistructured assessment of 110 outpatients was performed for 12 PDs and their 112 diagnostic criteria. GoM analysis was performed using internal variables of the 112 PD criteria rated as present or absent. Demographic variables, axis I and II diagnosis (structured clinical Interview for DSM [SCID]), and treatment response (Global Adjustment Scale [GAS]) information were used as external validators. Four pure types (PT) provided the most satisfactory solution to the data. PT-I is characterized by marked maladaptive personality pathology, which is manipulative, egocentric, impulsive, and alloplastic. PT-II consists primarily of exaggerated socially anxious and detached traits. PT-III is sociably dependent and autoplastic(. PT-IV is essentially asymptomatic. GoM provides a more parsimonious handling of the PD criteria than provided by classifying according to DSM categories. The analysis fails to confirm the natural occurrence of any single specific axis II PD or cluster. Copyright (C) 1999 by W.B. Saunders Company.