Mindfulness-based interventions (MBIs) improve depression symptoms after traumatic brain injury (TBI), with medium to large effect sizes. The goal of this study was to determine the clinical significance of individual changes in depression symptoms by examining data from three studies. Three criteria were used to assess the clinical significance of pre- to post-treatment change in Beck Depression Inventory-II (BDI-II) scores: (1) reliable change to account for measurement error, (2) five-point change to detect minimally important clinical differences, and (3) severity change to measure the severity of depression symptoms. The number of participants who met all three of these criteria (i.e., the three-criterion standard) was calculated for (a) all MBI participants across the three studies (N = 90) and for (b) only participants who completed the randomized controlled trial (study 3). According to the three-criterion standard, 50 % of TBI participants had BDI-II scores that clinically improved (45/90) and none had scores that deteriorated. When this standard was applied to study 3, more participants in the treatment group (20/38) had improved scores compared to controls (13/38). The majority of all participants also showed clinically improved BDI-II scores according to each of the separate criteria: reliable change (64/90), five-point change (49/90), and severity change (51/90). We suggest that (a) the three-criterion standard be considered the gold standard for assessing treatment-related change in depression symptoms, and (b) reporting the clinical significance of individual change may be more informative to clinicians when assessing the impact of MBIs on clients with TBI compared to findings based exclusively on group averages.
