Called the Prognosis in Palliative Care Study (PiPS) predictor model, the scoring system plugs 11 variables into a computer to see how many days, weeks or months a person with advanced cancer most likely has to live. These variables include symptoms, general health status and blood results.
"The PiPS score is still in development, [and] it is certainly not fail-safe," stressed study author Dr Patrick C. Stone, of St. George's University of London. "It is, however, slightly more reliable than a doctor's or a nurse's estimate of survival."
Many people with incurable cancer want this type of information, Stone added. "At this stage of a patient's illness, information about prognosis can allow patients sufficient time to prepare for their impending death and to make decisions about where they wish to be cared for," he said. "We would expect the PiPS score to complement the doctor's own intuitive estimate of survival, rather than replace their clinical judgment."
Estimating how long people have to live
The new system, which includes two scores (PiPS-A and PiPS-B), were at least as accurate as the predictions of doctors or nurses at determining how long 1,018 people with advanced cancer had left to live. PiPS-B includes blood work, and this particular score was better than any one doctor's estimate at predicting survival. Neither score is more reliable than a prediction that combines more than one medical opinion. The findings were reported in the BMJ.
There are some caveats, said Dr Paul Glare, chief of the department of pain and palliative care at Memorial Sloan-Kettering Cancer Center in New York City, including the fact that an electronic "app" is needed to use the new scoring system.
"They are developing an app, but we want simple tools that clinicians can use without a computer," he said. Another limitation is that the PiPS-B measures blood levels of C-reactive protein (CRP); in the United States, doctors do not routinely measure blood levels of this inflammation marker among people with advanced cancer.
Still, a tool would be helpful, Glare said. "Clinicians may give an optimistic spin so patients think they have much longer to live than they really do," he said. "Doctors normally overestimate this information by a factor of four or five," he noted. "We don't want to take away hope, but we should be at least as accurate as possible so people can plan."
How such information is communicated to patients and their loved ones also matters, Glare said.
There are always scenarios where people exceed expectations, he added, and understanding more about these outliers may help any future tools become more accurate.
To learn more about palliative care, visit the National Palliative Care Research Center.
SOURCES: Patrick C. Stone, M.D., St. George's University of London; Paul Glare, M.D., chief, department of pain and palliative care, Memorial Sloan-Kettering Cancer Center, New York City; Aug. 25, 2011, BMJ, online.
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