(PS8-C56) Latent Classes of Symptom Trajectories in a Brief Treatment for Borderline Personality Disorder

Borderline personality disorder (BPD) is a heterogeneous condition characterized by pervasive instability in interpersonal relationships, self-image, emotion, and impulsive behavioral responses. Given the heterogeneity in symptom presentation and the instability that characterizes BPD, it is likely that patients with this disorder progress through treatment in different ways. Characterizing patients’ treatment trajectories at the individual or subgroup level can facilitate the identification of unique treatment responses, deviation from anticipated progress, and personalized treatment plans. Researchers have consistently identified at least two classes of symptom trajectories during treatment for mood and anxiety disorders: (1) non-responders, who do not meaningfully improve and (2) responders, who demonstrate consistent improvement. Despite the identification of distinct classes of symptom trajectories in patients with mood and anxiety disorders, no research to date have sought to identify them in patients receiving treatment for BPD. Thus, the current study sought to identify and characterize BPD symptom trajectories among patients receiving a novel, 18-session cognitive-behavioral treatment for BPD. We used latent growth mixture modeling to explore potential BPD symptom trajectories among this population. In addition, we sought to examine whether baseline clinical factors (i.e., including mood symptoms, functioning, quality of life) or personality dimensions (i.e., negative affectivity, agreeableness, conscientiousness) predict membership in symptom class trajectories. The sample included 40 adult outpatients with DSM-5 BPD who were 85% female, 12.5% non-binary, 2.5% transgender and 95% white, with an average age of 28.0. Participants completed 18 sessions of BPD Compass, a novel, modular, cognitive-behavioral treatment for BPD that targets negative affectivity, disinhibition, and antagonism. Two distinct BPD symptom classes were identified in this sample: a low symptom starter class (n=35) and a high symptom starter class (n=5). Both classes demonstrated a decrease in symptoms at a similar rate, however, those in the high symptom starter class began treatment with significantly greater symptom severity. At baseline, the high symptom starter class also reported greater baseline severity across all clinical measures as well as higher neuroticism and lower conscientiousness. Those in the high symptom starter class also ended treatment with significantly greater symptom severity. These results demonstrate that distinct symptom trajectories can be identified in an outpatient sample of patients receiving treatment for BPD, and baseline clinical characteristics can be used to predict which of these trajectories a patient is likely to follow. If replicated, clinicians may use this information to identify likely symptom trajectories prior to treatment, as well as identify when a patient is following a trajectory likely to end in nonresponse, and therefore modify treatment accordingly. Finally, these results are based in sample data. Data collection will conclude in June 2023 with an expected sample size of N=100 for final analysis.