A university hospital conducts a randomized controlled trial to evaluate the efficacy of a new oral anticoagulant compared to standard therapy for the prevention of deep vein thrombosis (DVT) following total knee arthroplasty. The trial enrolls 1,200 patients, who are randomly assigned in a 1:1 ratio to either the new oral anticoagulant or standard therapy. The results over a 90-day postoperative follow-up period are presented in the table below:
| Group | Total Patients | Patients with DVT |
|---|---|---|
| New Oral Anticoagulant | 600 | 12 |
| Standard Therapy | 600 | 36 |
Based on these data, how many patients need to be treated with the new oral anticoagulant instead of standard therapy to prevent one additional case of DVT?
Answer: 25 patients
Answer
25
The Number Needed to Treat (NNT) is an epidemiological measure that indicates how many patients must receive a particular treatment to prevent one additional adverse event. It is calculated as the inverse of the Absolute Risk Reduction (ARR). In this study, the ARR is the difference in deep vein thrombosis incidence between the standard therapy group () and the new oral anticoagulant group (). Therefore, . The NNT is . This means 25 patients must be treated with the new anticoagulant instead of standard therapy to prevent one DVT.
Step-by-Step Solution
Key Concept
Number Needed to Treat (NNT)