Personality Disorders in Primary Care: Impact on Depression Outcomes Within Collaborative Care

Individuals with personality disorders (PDs) are high utilizers of primary care and mental health services; however, they struggle to utilize the care effectively and studies have shown a strong association between having a PD and higher impairment in social role functioning. This is especially important because PDs are highly comorbid with a wide range of other mental health disorders. The collaborative care model (CCM) for depression was developed with an emphasis on patient engagement and aimed to reduce health care utilization, while improving treatment outcomes in primary care. We hypothesized that the diagnosis of a personality disorder in primary care patients will negatively affect 6-month depression outcomes after enrollment into a CCM.

This retrospective chart review study was conducted on patients enrolled into CCM over a period of 7 years with collection of 6-month follow-up data. A total of 2826 patients were enrolled into CCM with a clinical diagnosis of depression and a baseline Patient Health Questionnaire-9 (PHQ-9) ≥10 were included in the study cohort. Using the depression database, baseline and 6-month follow-up data were obtained. Adjusted odds ratios (AORs) were determined for both remission and persistent depressive symptoms using logistic regression modeling for the 6-month PHQ-9 outcome; while retaining all the study variables.

Of the 2826 CCM patients with depression in our study, 216 (7.6%) were found to have a PD. Patients with PD were younger (37.7 vs 42.5 years, P < .001) and more likely to be unmarried (36.1% vs 55.6%, P < .001) than patients without a PD. While age, marital status, clinical diagnosis, and Mood Disorders Questionnaire (MDQ) score were significant predictors of remission; anxiety symptoms, gender, and race were not. The presence of a PD diagnosis was associated with a 60% lower likelihood of remission at 6 months (AOR = 0.39; 95% CI 0.28-0.54). Conversely, patients without a PD were 2.5 times as likely to experience remission at 6-month remission compared to patients with PD (AOR =2.57; 95% CI 1.85-3.56).

Patients with a personality disorder were more likely to have a recurrent depressive disorder diagnosis, an abnormal MDQ score, increased anxiety symptoms, and higher baseline PHQ-9 score. Patients with PD had worse CCM outcomes at 6 months with only 25.0% able to achieve remission versus 54.3% ( P < .001) without a PD. The presence of a PD with depression was associated with poor outcomes (reduced remission rates and increased persistent depressive symptoms rates) in comparison to patients without a diagnosis of PD, while treated within CCM.