Treatment process evaluation: the role of personality functioning

Background: Treatment engagement is a major factor contributing to favourable outcome of drug treatment, but high dropout rates persist. It has remained difficult to draw conclusions regarding specific predictors of engagement, but there is a clear need to identify and target clients’ major attrition vulnerabilities. Despite evidence of the association of personality with drug misuse, little is known about its role in the treatment process. Aims: This study set out to examine whether, and to what extent, personality functioning contributes to or hinders individuals’ treatment journeys. The study examined service users’ personality characteristics as potential determinants of treatment initiation, engagement and completion and whether characteristic adaptations are malleable during treatment. Methodology: A longitudinal multi-site design was utilized, examining the therapy process in a naturalistic setting in outpatient and inpatient treatment centres. The first part of the study examined whether service users’ personality traits (TPQue) and characteristic adaptations (SIPP-118) predict treatment initiation (CEST-Intake), involving n = 200 from 5 outpatient preparation treatment centres. The second part examined whether characteristic adaptations predict treatment engagement (CEST) and completion involving n = 340 participants from 6 inpatient centres. Multivariate regression analyses were applied for hypotheses testing. The final part of the study explored the malleability of characteristic adaptations and examined whether clinically significant change occurred in dysfunctional characteristic adaptations (n = 70). A series of mixed between-within subject analyses of variance were conducted to compare service users who dropped out and those who completed treatment across the two-time periods. Results: Findings indicated that certain dysfunctional characteristic adaptations are associated with treatment initiation (RQ1) and drop out (RQ3). Broad and facet level characteristic adaptation emerged as strong predictors on different segments of treatment engagement (RQ2). Dysfunctional levels on Self-control and Relational capacities significantly predicted low counselling rapport and treatment participation. The analyses at the facet level provided additional insight of the important role of Identity and Relational capacities on initiation, engagement and treatment completion. The final step shed light on the malleability of characteristic adaptations during treatment and revealed that completers had more functional characteristic adaptations at baseline and had higher levels of significant clinical improvement (RQ4). Only Social concordance remained unchanged at the second inpatient time point. This has important clinical implications considering that Social concordance and especially the Aggression regulation facet was the strongest predictor of treatment initiation, counselling rapport and treatment completion. Conclusions: These findings extend our knowledge of the predictive role of characteristic adaptations in the treatment process, and suggest it may be important to capture these individual differences early on. Delineating the role of characteristic adaptations in treatment engagement and their sensitivity to change under treatment may provide the basis for enhancing treatment specificity through individualized interventions that are scientifically-driven and empirically-validated. This is of major clinical relevance, since it provides a node-link mapping of early warning signs of individuals’ maladaptive areas that require clinical attention and may open new avenues for the scientific enquiry of personality and treatment