Evaluating a problem-based empowerment program for African Americans with diabetes: results of a randomized controlled trial.

Abstract

We believe that results of this study can be attributed to volunteer bias, study effects (ie, providing study data on several occasions to patients and their physicians during the one-year study period), and impact of the interventions. However, the study design does not allow us to examine the relative impact of these three factors on the patient improvements seen over the one-year study period.