From efficacy in trials to effectiveness in clinical practice: The Swedish Stroke Prevention Study.

Blood pressure treatment has shown great efficacy in reducing cardiovascular events in randomized controlled trials. If this is effective in reducing cardiovascular disease in the general population, is less studied. Between 2001 and 2009 we performed an intervention to improve blood pressure control in the county of Västerbotten, using Södermanland County as a control. The intervention was directed towards primary care physicians and included lectures on blood pressure treatment, a computerized decision support system with treatment recommendations, and yearly feed back on hypertension control. Each county had approximately 255 000 inhabitants. Differences in age and incidence of cardiovascular disease were small. During follow-up, more than 400 000 patients had their blood pressure recorded. The mean number of measurements was eight per patient, yielding a total of 3.4 million blood pressure recordings. The effect of the intervention will be estimated combining the blood pressure data collected from the electronic medical records, with data on stroke, myocardial infarction and mortality from Swedish health registers. Additional variables, from health registers and Statistics Sweden, will be collected to address for confounders. The blood pressure data collected within this study will be an important asset for future epidemiological studies within the field of hypertension.