Most doctors are too optimistic in predicting how long dying patients have to live, and this has a negative effect on the care they receive in their final days, American researchers said Friday. A study by scientists at the University of Chicago Medical Center in Illinois showed that of the survival estimates for 486 terminally ill patients given by 343 doctors, (46) . (47) , and in some cases doctors predicted patients had five time longer to live than proved to be the case. 'Doctors are inaccurate in their prognoses(预后)for terminally ill patients and the error is systematically optimistic,' professor Nicholas Christakis and Dr Elizabeth Lamont said in a report in The British Medical Journal. The researchers added that doctors who knew their patients best were more likely to get it wrong. ' (48) ...the type of systematic bias toward optimism that we have found in doctors' objective prognostic assessments may be adversely(不利地)affecting patient care,' the researchers added. Instead of receiving three months of hospice care, which is considered to be the ideal, (49) . Patients who thought they had longer to live also opted for more aggressive treatment instead of palliative(治标的)care, the report said. The researcher suggested doctors should get second opinions from colleagues, (50) , before giving a prognosis. 'Reliable prognostic information is a key determinant in both doctors' and patients' decision making,' they said.