The failure to prevent stroke in AF is similar to the crisis in VTE prevention among hospitalized patients from a decade ago. To address this critical patient safety problem, we evaluated the impact of alert-based CDS on VTE prevention (18). First, we designed software linked to our Electronic Health Record (EHR) and provider order entry program to identify hospitalized patients at risk for VTE using a weighted risk score and for whom prophylaxis was not ordered. Patients were randomized to the intervention group, in which the responsible physician received an electronic alert regarding the risk of VTE and recommendation regarding prophylaxis, or to the control group, in which no alert was issued. Compared with the control group, electronic alerts more than doubled the rate of thromboprophylaxis orders (from 14.5% to 33.5%; p<0.0001). The risk of symptomatic VTE was reduced by 41% (hazard ratio, 0.59; 95% confidence interval 0.43-0.81; p=0.001) among patients for whom an electronic alert was issued. We have also shown that "human" (person-to-person) alert-based decision support for the prevention of VTE in at-risk hospitalized patients more than doubled the rate of VTE prophylaxis compared with controls during hospitalization (21) and after discharge (19).