Fibromuscular dysplasia of renal arteries: a neglected cause of acute loin pain.

discipline, and encouraging recruitment through its own networks of medical representatives and researchers. Whatever the cost of a trial, it should be compared with the cost of the disease being treated and, perhaps, against the cost of non-medical endeavours such as low altitude military aircraft training or unemployment benefit. By any such comparisons multicentre trials are usually extremely inexpensive and may lead to the rejection of expensive but ineffective treatments-for example, extracranial to intracranial bypass surgery for the prevention of stroke-and not always to the introduction of more expensive health care.