Canadian researchers have developed a new tool they say can help doctors predict the likelihood that a patient will die or be readmitted to hospital within 30 days of being discharged.

The tool, called the LACE index, was developed to help doctors and others in the health system to understand which kind of patients are at highest risk of problems after they are discharged and who therefore needs the most support.

Dr. Carl van Walraven of the Ottawa Hospital Research Institute says he and his team came up with the tool after collecting data from almost 5,000 patients who were admitted to 11 Ontario hospitals between October 2002 and July 2006.

Most of the patients were middle-aged and were hospitalized for such things as acute coronary syndromes, cancer complications and heart failure.

The patients' health was followed for up 30 days after they left hospital.

The researchers found that eight per cent of the patients died or were readmitted within the next month. Of them, 9.4 per cent died, and 90.6 per cent had an unplanned readmission.

Using the data, the researchers came up with a mathematical model to estimate the probability of a bad outcome. They say after analyzing all the reasons that send patients back to hospital, it all came down to four key variablesr:

• the patient's length of stay in hospital
• how acute or severe their condition was when they were admitted
• their comorbidities, or other health conditions they had along with the reason they went to hospital
• and their history of emergency department use.

The index is called LACE: length of stay ("L"), acuity of admission ("A"), comorbidities ("C") and number of visits to the emergency room ("E").

Patients can be given a score of 0 to 19; the higher the score, the more likely they will be readmitted or die.

The researchers then used data from ICES, the Institute for Clinical Evaluative Sciences, and externally validated the model in a million different patients in Ontario.

Details on how the index was developed were published Monday by the Canadian Medical Association Journal.

The idea is that a high score on the index could be a signal to care providers that the patient will need extra attention in the days to come.

So that might mean, for example, that a patient would use more post-discharge phone calls to see how they are doing. It could also mean giving the patients detailed instructions telling them when to see their family doctor again or when to seek medical care.

"We believe that the LACE index can be used by clinicians, researchers and administrators to predict the risk of early death or unplanned readmission of cognitively intact medical or surgical patients after discharge from the hospital to the community," the researchers write.

The researchers say they would like to see further research to determine if identifying the risk of poor death or readmissions changes patient outcomes.