Liam Donaldson, Britain's Chief Medical Officer, says that we may be safer on a plane than in hospital. It seems the risk of being killed by a medical error in a developed country is about 1 in 300; the risk of dying in an air accident is 1 in 10 million.

Actually, it depends whose figures you take. The NAO recently said (PDF) that more than 2000 people a year die as a result of medical errors. The most common causes of error are: patient injury (due to falls), followed by medication errors, equipment related incidents, record documentation error and communication failure.

The NAO admits that the actual number of deaths by medical accidents is unknown, and there may be significant under reporting. Estimates range from 840 to 34,000 a year.

Based on Liam Donaldson's ratio and using an estimate of about 8m admissions to the NHS annually based on the NPSA report "Right Patient, RIght Care" (PDF), this would put the number of deaths caused by medical errors at about 26,000 a year.