Short-term diagnostic stability of schizotypal, borderline, avoidant, and obsessive-compulsive personality disorders.

OBJECTIVE: Personality disorders are defined as enduring patterns of maladaptive behaviors and traits that are stable over time. This study prospectively examined the stability of four personality disorders (schizotypal, borderline, avoidant, and obsessive-compulsive) over a 1-year follow-up period.
METHOD: Subjects (N=668) were recruited from multiple clinical settings at four collaborating institutions. Subjects met criteria for one or more of the four personality disorders or were part of a comparison group of subjects with major depressive disorder and no personality disorder. Diagnoses were established by using semistructured interviews. Follow-up assessments, conducted 6 and 12 months after the baseline assessment, included monthly ratings of all criteria for the four personality disorders and weekly ratings of the course of major depressive disorder. The current report is based on 621 subjects with complete data through 12 months of the follow-up period.
RESULTS: Significantly more subjects in each personality disorder group remained at diagnostic threshold throughout the 12 months of the follow-up period than did those in the major depressive disorder group. A continuous measure of number of criteria met was highly correlated across the three assessments. The majority of personality disorder subjects, however, did not consistently remain at diagnostic threshold, and the mean number of criteria met decreased significantly for each group.
CONCLUSIONS: Individual differences in personality disorder features appear to be highly stable, although the number of criteria present decreases over time. Personality disorders may be characterized by stable trait constellations that fluctuate in degree of maladaptive expression.