"CoMBI-SMI Multicenter Study: A Person-Centered Cognitive-Behavioral Intervention for Severe Mental Illness"

This multicenter observational study investigates the effectiveness of a treatment protocol for a personalized approach to behavioral problems in individuals with severe mental illness (SMI), grounded in patients' core psychological needs derived from their specific personality traits. Participants will be recruited from specialized mental health care institutions in the Netherlands, Belgium, and the Caribbean. Both adults (aged 18-64 years) and older adults (≥65 years) with SMI will be included.

The study employs a stepped-wedge design, where all participating teams initially provide treatment as usual (TAU), with outcome measurements every four weeks. At staggered time points, teams will be trained in the CoMBI-SMI intervention and transition to providing care based on this model. CoMBI-SMI (Cognitive Model for Behavioral Interventions - Severe Mental Illness) is a mediation-based approach in which behavioral interventions are implemented through a multidisciplinary team, rather than individual therapy. This model is particularly suited for the SMI population, where direct psychotherapy is often unfeasible due to lack of motivation or cognitive limitations.

The CoMBI-SMI intervention is based on Beck's cognitive model of personality disorders and integrates structured nursing interventions from the Nursing Interventions Classification (NIC). The intervention begins with the identification of maladaptive behavior patterns by the care team. These behaviors are analyzed in terms of their environmental triggers and maintaining consequences. A relevant core need is then selected from the CoMBI-SMI framework, and corresponding team-based interventions are planned. These are documented in a CoMBI care plan and implemented in a cyclical, evaluation-based format.

Primary outcome measures are the Neuropsychiatric Inventory Questionnaire (NPI-Q), assessing behavioral symptoms and associated distress, and the Brief Symptom Inventory (BSI), measuring psychological symptom severity. Secondary outcomes include perceived caregiver burden (NPI-Q distress scores) and patient-reported quality of life, measured by the Mental Health Quality of Life scale (MHQoL-7D). In addition, the study will identify predictive factors for treatment response using personality assessment tools: the Personality Inventory for DSM-5 - Brief Form + Modified (PID-5-BF+M) and the Level of Personality Functioning Scale - Brief Form 2.0 (LPFS-BF 2.0).

The NPI-Q data will also be used for a validation substudy in the SMI population, evaluating the instrument's construct validity, internal consistency, and inter-rater reliability.

Healthcare providers in participating departments will be trained in the CoMBI-SMI protocol. Training consists of an online theoretical module followed by a Meet-the-Expert (MTE) session, where providers can discuss theory and practice the application of CoMBI-SMI using clinical case studies. Completion of the training requires passing case-based assessments that evaluate theoretical understanding and clinical reasoning.

This study aims to improve behavioral management in SMI, enhance team competence in dealing with complex behaviors, and contribute to the development of structured, theory-based protocols for mediation therapy in psychiatry.

• Mental Health Quality of Life (MHQoL-7D): Total Score and Visual Analogue Scale (VAS) [Срок оценки: At baseline (before the start of treatment-as-usual) Immediately before the start of CoMBI-SMI training At week 5 (after 4 weeks of CoMBI-SMI-based care).]