Shea et al. (1990) found that Cluster C disorders had lower attrition (28%) by end of treatment than did Cluster A or B personality disorders. Avoidant patients generally stay in shorter-term treatments, but in the longest treatment duration reported, Barber et al. (1997) found that 46% dropped out before the intended 50 sessions, which contrasted with 7% attrition in an OCPD treatment arm. Karterud et al. (2003) found that those with DPD had lower attrition (16%) from an 18-week day-treatment program than all other personality disorder types except schizoid. In a study of long-term therapy, my colleagues and I found that DPD was the only personality disorder type associated with retention (Perry et al. 2005).