The hospital routine of giving patients the drug heparin as a just in case precaution against fatal pulmonary embolism (blood clot in the lung) is of no benefit, researchers have discovered.

The condition is common in hospital, and is thought to occur because patients are immobile for long periods. It also tends to affect older patients, usually those over 55. Surprisingly, 75 per cent of all fatal cases occur in patients who have not had any surgery.

Researchers have found that heparin does nothing to prevent an attack; at best, the drug may merely delay it. They are calling on international health groups to stop recommending the routine use of heparin, particularly for patients not having surgery.

The Heparin Prophylaxis Study Group looked at two groups of patients 5,776 were given heparin and 5,917 had no treatment. The heparin group were no better off after three weeks of heparin, although any attack was delayed until they came off the drug.

But they made the discovery only because they carried out a long term study, which included the monitoring of patients for three weeks after they were released from hospital. A shorter study, they pointed out, would have given a false picture of the beneficial effects of the drug.

!AThe Lancet, May 18, 1996.