Your chances of suffering a serious reaction to a drug while in hospital stand at around 6.5 per cent; worse, 42 per cent of serious reactions are caused by staff error.
These findings, based on monitoring two hospitals in America for six months, show that hospitals have become more dangerous than when a similar study was last carried out.
The 1984 Medical Practice Study revealed that just under 4 per cent of hospital patients would suffer "an adverse event", or injury due to medical treatment. The study found that 69 per cent of injuries were preventable.
The new study, carried out by the Brigham and Women's Hospital in Boston, Massachusetts, shows that drug reactions alone far outstrip previous findings, which included other medical treatment.
Errors mainly occur when drugs are first ordered; this accounted for 56 per cent of all errors that were preventable. Administrative mistakes made up a further 36 per cent of errors, while the remainder happened because of transcription (6 per cent), and dispensing (4 per cent)
The discovery was made by monitoring 4,031 adults admitted to two hospitals over a six-month period.
Of these, 247 drug side effects were reported, and a further 194 potential reactions were also identified. One per cent resulted in death, 12 per cent were life-threatening, 30 per cent were serious and the remainder were "significant".
The figures make for horrifying reading. Even back in 1984, by extrapolating the findings of the time, over one million Americans were being injured in hospital every year, and 180,000 died as a result.
"The iatrogenic injury rate dwarfs the annual automobile mortality of 45,000 and accounts for more deaths than all other accidents combined," the report writers point out (JAMA, July 5, 1995).
Doctor ignorance was cited as a major reason for error, another study has discovered. Physicians seemed to be unaware of correct dosage and when a drug should be given.
The problem accounted for 29 per cent of errors, while a lack of information about the patient was responsible for a further 18 per cent.
The study, by the Harvard School of Public Health, identified 334 incidents of error which