The impact of comorbid personality difficulties on response to IAPT treatment for depression and anxiety

Abstract The UK's Improving Access to Psychological Therapies (IAPT) initiative provides evidence-based psychological interventions for mild to moderate common mental health problems in a primary care setting. Predictors of treatment response are unclear. This study examined the impact of personality disorder status on outcome in a large IAPT service. We hypothesised that the presence of probable personality disorder would adversely affect treatment response. Method We used a prospective cohort design to study a consecutive sample of individuals (n = 1249). Results Higher scores on a screening measure for personality disorder were associated with poorer outcome on measures of depression, anxiety and social functioning, and reduced recovery rates at the end of treatment. These associations were not confounded by demographic status, initial symptom severity nor number of treatment sessions. The presence of personality difficulties independently predicted reduced absolute change on all outcome measures. Conclusions The presence of co-morbid personality difficulties adversely affects treatment outcome among individuals attending for treatment in an IAPT service. There is a need to routinely assess for the presence of personality difficulties on all individuals referred to IAPT services. This information will provide important prognostic data and could lead to the provision of more effective, personalised treatment in IAPT.