Evaluating Dose Response of Cognitive Behavioural Therapy Using Outpatient Electronic Medical Record Data: An Observational Study: Évaluer la relation dose-réponse de la thérapie cognitivo-comportementale au moyen des données des DME des patients externes : Une étude d'observation.

ObjectiveAccess to cognitive behavioural therapy (CBT) in Canada is limited by long wait times. Our objective was to determine the optimal dose of CBT sessions for patients to maximize recovery and minimize treatment time.MethodOutpatient data from electronic medical records at a specialized mental health centre between 1 January 2017 and 31 May 2024 was used. The primary outcome was having experienced a reliable and clinically significant improvement (RCSI) in symptoms since start of treatment. Kaplan-Meier estimators were used to determine the percentile who had achieved RCSI after a given number of CBT sessions. Adjusted Cox regression determined predictors of treatment response.ResultsAmong patients (n = 1,853) receiving treatment, 50% showed response in Patient Health Questionnaire-9 (PHQ-9) scores at 7 sessions of low-intensity CBT (LiCBT) and 95% showed response at 23 sessions. For high-intensity CBT (HiCBT), treatment response occurred between 14 and 36 sessions for 50-95% of patients. In Generalized Anxiety Disorder Assessment-7 (GAD-7) scores, treatment response occurred between 8 and 30 sessions in LiCBT and 15 and 37 sessions in HiCBT for 50-95% of patients. Cox regression results found that neighbourhood dependency [PHQ-9: hazard ratio (HR) (95% confidence interval (CI)) = 1.32 (1.08 to 1.63), GAD-7: HR (95% CI) = 1.36 (1.12 to 1.65)] and sex (male) [PHQ-9: HR (95% CI) = 0.83 (0.70 to 0.99), GAD-7: HR (95% CI) = 0.80 (0.66 to 0.96)] were significant predictors of non-response in HiCBT. Older age at admission was a significant predictor of non-response to LiCBT [PHQ-9: HR (95% CI = 0.99 (0.98 to 1.00), GAD-7: HR (95% CI) = 0.99 (0.98 to 1.00)].ConclusionsThere are differences in the dose and the predictors of patients' responses to LiCBT and HiCBT. These results provide insight into potential check-in points for clinicians to assess CBT treatment plans. These results may inform treatment planning, reducing longer than necessary length of stays, allowing for more patients to access mental healthcare services.