The control group provides a neutral index against which to measure the effects of the actual drug. The trouble is that half the patients go untreated in a controlled trial. With Lassa fever, we knew that many untreated patients would die. Because the laboratory data looked promising, our committee had determined that we should not use an untreated group in our study. We determined, therefore, to compare the results in our new patients with data from previous untreated patients.
