Improving health outcomes among youth with poorly controlled type I diabetes: The role of treatment fidelity in a randomized clinical trial of multisystemic therapy.

The purpose of the study was to assess whether therapist treatment fidelity was a predictor of treatment outcome in a randomized clinical trial of multisystemic therapy with 10- to 16-year-old youths with chronically poorly controlled Type I diabetes (N = 40). Treatment fidelity was assessed by objective ratings of therapy sessions and questionnaires completed by caregivers and by therapists. Relationships between fidelity measures were assessed. Structural equation modeling (SEM) was used to test whether high fidelity would lead to improved regimen adherence and to improved metabolic control outcomes via regimen adherence. Objective ratings of treatment fidelity were significantly related to therapist-reported but not to caregiver-reported treatment fidelity. SEM results supported a completely mediated pathway between treatment fidelity and metabolic control, with regimen adherence mediating the relationship. Results suggest that conducting complex behavioral interventions with a high degree of fidelity can improve treatment outcomes among youths with chronic illnesses.