Purpose: We conducted an observational study of the implementation of guidelines for hypertension among patients with diabetes. We hypothesized that the highest level of guideline-concordant care would be achieved where implementation strategies (education, motivation/incentive, or barrier reduction) fit well with physicians' cognitive styles as measured on a psychometric instrument we have previously described at SMDM.

Methods: 165 physicians at 43 VHA medical center primary care clinics completed the psychometric scales. Outcomes were decisions made by the 165 physicians for treating 1174 patients' blood pressures. Decisions were designated guideline-concordant if the patient's blood pressure was within goal range (< 140/90, as the VHA had not shifted to 130/80 at this time), or if the blood pressure was out of range and a dose change or medication change was initiated, or if the patient was already using medications from 4 classes. Guidelines implementation strategies were classified using a pre-specified system. Analysis was by logistic regression correcting for clustering by physician.

Results: Factor analysis confirmed the 3-factor psychometric scaling used previously. The only type of intervention that was associated with increased guideline-concordant care was barrier reduction (p < 0.02). The interaction between the conformity scale and intervention was significant (p < 0.05).

Conclusions: Guidelines implementation strategies that were designed to reduce, or at least not increase, physician time demands and task complexity were the only ones that improved performance. Education may have been necessary but was clearly not sufficient: all sites included education in their mix of strategies, but those doing a great deal of it saw no more effect than those doing the minimum. Incentives had no discernible effect. The interaction between the conformity scale and implementation strategy showed that barrier reduction was necessary for performance improvement for all physicians except the handful that were most inclined to "swim against the tide", the group described as "seekers" in our prior presentation.