P5407Predicting adherence to internet-delivered cognitive behaviour therapy for comorbid symptoms of depression and anxiety after myocardial infarction

Background: Psychotherapeutic treatment for the subgroup of patients with MI that also suffer from comorbid symptoms of anxiety and/or depression (MI-ANXDEP) is part of cardiac rehabilitation (CR). Adherence to a range of treatments and lifestyle advice is crucial for risk reduction in these patients. Understanding the relative importance of predictors of adherence to internet-delivered cognitive behaviour therapy (ICBT) for MI-ANXDEP could improve their targeted care. Purpose: We estimated the relative importance of a range of established and novel predictors of adherence to ICBT for MI-ANXDEP patients. Method: The study sample consisted of 90 MI-ANXDEP patients (58.4 years, 62% men) recruited from 25 hospitals in Sweden who were randomised to active treatment in the ICBT trial U-CARE Heart. Time-point of prediction was at completion of the first homework assignment (HWA), and adherence was gauged at the end of treatment (48% adherers). Adherence was defined as completing at least the first two HWAs within the 14-week treatment period. A supervised machine learning (ML) procedure, applying 3x10 cross-validated recursive feature elimination with a random forest model as internal classifier, estimated the relative importance of predictors for adherence from a range of patient demographic, clinical, and linguistic variables that were available at completion of the first HWA.