Evaluation of computer based clinical decision support system and risk chart for management of hypertension in primary care: randomised controlled trial

Objectives To investigate the effect of a computer based clinical decision support system and a risk chart on absolute cardiovascular risk, blood pres sure, and prescribing of cardiovascular drugs in hypertensive patients. Design Cluster randomised controlled trial. Setting 27 general practices in Avon. Participants 614 patients aged between 60 and 79 years with high blood pres sure. Interventions patients were randomised to computer based clinical decision support system plus cardiovascular risk chart; cardiovascular risk chart al one; or usual care. Main outcome measures Percentage of patients in each group wit a five year cardiovascular risk greater than or equal to 10%, systolic blood pressure, diastolic blood pressure, prescribing of cardiovascular drugs. Results Patients in the computer based clinical decision support system and chart only groups were no more likely to have cardiovascular risk reduced to below 10% than patients receiving usual care. Patients in the computer b ased clinical decision support group were more likely to have a cardiovascu lar risk greater than or equal to 10% than chart only patients, odds ratio 2.3 (95% confidence interval 1.1 to 4.8). The chart only group, had signifi cantly lower systolic blood pressure compared with the usual care group (di fference in means - 4.6 mm Hg (95% confidence interval - 8.4 to - 0.8)). Re duction of diastolic blood pressure did not differ between the three groups . The chart only group were twice as likely to be prescribed two classes of cardiovascular drugs and over three times as likely to be prescribed three or more classes of drugs compared with the other groups. Conclusions The computer based clinical decision support system did not con fer any benefit in absolute risk reduction or blood pressure control and re quires further development and evaluation before use in clinical care can b e recommended. Use of chart guidelines are associated with potentially impo rtant reduction in systolic blood pressure.