In praise of human guinea pigs

BEFORE the 20th century, the sick were wise to stay away from doctors. Medical treatments were often worthless and sometimes dangerous: “heroic measures” such as blood-letting and purging often killed. It was the discovery of micro-organisms, vaccines and antibiotics, that eventually equipped doctors with weapons that whacked diseases, not patients. But as many lives may have been saved by a more recent innovation, the randomised controlled trial (RCT). The idea is simple, yet brilliant. A new treatment is tested by giving it only to some randomly chosen patients, with the rest (the “controls”) receiving standard care. Before RCTs became common in the 1950s it was easy for a doctor to believe that patients who died did so despite his best efforts, while those who survived owed him their lives. He might harm patient after patient and never spot the pattern. Now almost all medicines are tested with RCTs before being widely prescribed.What works in the fight against disease can also work in the fight against poverty. In the past decade aid organisations and governments in the developing world have rushed to make use of RCTs, encouraged by donors and philanthropists who like evidence that their cash will be spent well. This week two leading researchers released the results of RCTs for two schemes that gave destitute people assets (usually goats or a cow) and trained them to manage them (see ). The results were impressive: in India recipients were much better off five years after the programme ended. More important, the trials showed that it really was the aid programmes that made the difference, and not some other factor.