Development and preliminary validation of the treatment adherence rating scale

Patient adherence to treatment is an important barrier to the implementation of evidence-based psychological treatments (EBPTs). There is a need for simple and deployable measures of patient adherence to treatment for use across EBPTs. The Treatment Adherence Rating Scale (TARS) was developed and validated in two samples.

This study includes two samples: adults with Major Depressive Disorder who received Cognitive Therapy for depression (Sample 1; N = 48, mean age = 44.27 years), and at-risk adolescents who received either the Transdiagnostic Sleep and Circadian Intervention or Psychoeducation (Sample 2; N = 176, mean age = 14.77 years). Factor structure of the TARS scores was examined via Exploratory Factor Analyses (EFA) in Sample 1 and Confirmatory Factor Analyses (CFA) in Sample 2. Internal consistency, predictive validity, and construct validity of the TARS scores were examined.

Results from EFA in Sample 1 supported a one-factor model. Results from CFA in Sample 2 suggested that a two-factor model (i.e., agreement and compliance) fit better than a one-factor model. TARS scores from both samples demonstrated adequate predictive validity with primary clinical outcomes and construct validity with treatment expectations.

The sample was small with two specific populations. Future research should focus on other patient populations, a larger population, and other EBPTs. Future research examining patient ratings of these items are needed for further validation of the TARS.

Preliminary findings support the use of a two-factor model and highlight the potential utility of a simple measure of patient adherence to treatment across age and diagnostic groups.