Predictors of treatment response for depression and inadequate social support--the ENRICHD randomized clinical trial

To determine whether the 'dose' of treatment exposure, delivery of specific components of cognitive behavior therapy (CBT), patient adherence and/or use of antidepressants predict favorable depression and social support outcomes after 6 months of cognitive behavioral treatment.

Secondary analyses of the intervention arm of the Enhancing Recovery in Coronary Heart Disease (ENRICHD) clinical trial involving persons with acute myocardial infarction (MI): n = 641 for the depression outcomes and n = 523 for the social support outcomes. The outcome measures were, for depression: the Beck Depression Inventory (BDI) and Hamilton Rating Scale for Depression (HAM-D); for social support: the ENRICHD Social Support Instrument (ESSI) and Perceived Social Support Scale (PSSS).

Better depression outcomes (measured by the BDI) were receiving a high number of depression-specific intervention components, p < 0.01, and completing a high proportion of homework assignments, p < 0.02. Better depression outcomes (measured by the HAM-D) were receiving a high number of the social communication and assertiveness components of the intervention, p < 0.01, and completing a high proportion of homework assignments, p < 0.01. Better social support outcomes (measured by the ESSI and PSSS) were predicted by membership in a racial or ethnic minority group, p < 0.02 and p < 0.01, respectively; and by completing a higher number of homework assignments, p < 0.01 and p < 0.05, respectively. Delivery of the social communication and assertiveness components of the intervention was an independent predictor of a worse social support outcome, p < 0.01 (measured by the PSSS).

The standard components of CBT for depression are useful in treating comorbid depression in post-MI patients. Working on communication skills may help to improve depression but not necessarily social support outcomes in this patient population, while adherence to cognitive-behavioral homework assignments is important for both outcomes. Other components of the ENRICHD intervention that were designed to improve social support had no discernible effects on outcomes. Intervention refinements may be needed in order to achieve better results in future post-MI clinical trials. A greater emphasis on CBT homework adherence could improve both depression and social support outcomes.