Background and Aim: Personality functioning is predictive of drug misuse and relapse, yet little is known about the role of personality in engagement with the treatment process. This study aimed to estimate the extent to which broad‐ and facet‐level characteristic adaptations contribute to or hinder treatment engagement, while controlling for psychosocial indicators.
Design: Multi‐site cross‐sectional survey.
Setting: In‐patient treatment units covering 80% of residential treatment entries in Greece.
Participants: A total of 338 service users, 287 (84.9%) male, 51 (15.1%) female, average age 33.4 years.
Measurements: Expressions of personality functioning (characteristic adaptations) were assessed using the Severity Indices of Personality Problems (SIPP‐118). Treatment engagement was measured using the Client Evaluation of Self and Treatment, in‐patient version (CEST).
Findings: Dysfunctional levels of relational capacities predicted counselling rapport [β = 1.50, 95% confidence interval (CI) = 0.326–2.69, P = 0.013], treatment participation (β = 2.09, 95% CI = 1.15–3.11, P < 0.001) and treatment satisfaction (β = 1.65, 95% CI = 0.735–2.57, P < 0.001). Counselling rapport was also predicted by dysfunctional levels in self‐control (β = 1.78, 95% CI = 0.899–2.67, P < 0.001), self‐reflective functioning at the facet‐level (β = 2.24, 95% CI = 1.01–3.46, P < 0.001) and aggression regulation (β = 1.43, 95% CI = 0.438–2.42, P = 0.005). Dysfunctional levels on social concordance (β = −1.90, 95% CI = −2.87 to –0.941, P = 0.001), emotional regulation (β = 1.90, 95% CI = 0.87–2.92, P < 0.001) and intimacy (β = 2.04, 95% CI = 1.31–3.05, P < 0.001) were significant predictors of treatment participation. Treatment readiness and desire for help predicted treatment engagement.
Conclusions: In people attending substance use treatment services, maladaptive interpersonal patterns and relational intimacy, emotional dysregulation and impulse control may be associated with low levels of counselling rapport and treatment participation. Low frustration tolerance and aggressive impulses also appeared to predict low participation.