Venous thromboemboli (VTE) are abnormal blood clots that commonly form in the blood vessels of the legs or lungs. They can block normal blood flow, damage organs, and even cause death. The risk of VTE is increased in people who are sick or immobile. VTE is the most common preventable cause of death in hospitalized patients, and its VTE prevention should be a top patient safety priority. Though there is good evidence that injectable blood thinners and/or compression stockings can prevent VTE, over 30% of hospitalized medical patients in Hamilton, Ontario receive inappropriate prevention. Hamilton Health Sciences Corporation is in the process of introducing "electronic order sets" - computer programs that help doctors order medications and other healthcare interventions for their patients. The investigators would like to study if these electronic order sets can help improve the rate of appropriate VTE prevention in hospitalized medical patients. The investigators will examine the rate before and after the introduction of electronic order sets at the Juravinski Hospital and the Hamilton General Hospital. Doctors at the Hamilton General Hospital will also get to use an additional computer program, called a computerized decision support system (CDSS), that helps them decide on the best strategy to prevent VTE in individual patients. The rates of VTE prevention at each hospital will be compared to each other, and to the rates at St. Joseph's Healthcare Hamilton, which will receive neither the order sets nor the CDSS.

Inclusion Criteria:

• Adult patients at least 18 years of age
• Hospitalization on a general internal medicine ward

Exclusion Criteria:

• Receiving therapeutic anticoagulation at time of hospitalization