Several published prognostic indices can predict overall mortality for older adults, but none are ready for prime time, researchers reported.
A systematic review found 16 such indices, all developed in one group and validated in a second cohort, according to Alexander Smith, MD, of the University of California San Francisco, and colleagues.
But they all suffer from flaws that limit their clinical value, Smith and colleagues reported in the Jan. 11 issue of the Journal of the American Medical Association.
The study concluded that future research needs to independently test the accuracy of prognostic indices in heterogeneous populations, and their ability to improve outcomes, before widespread use can be recommended.
"Failure to consider prognosis in the context of clinical decision making can lead to poor care," the authors note, and validated prognostic indices offer the possibility of improved guidance.
But little is known about the quality of such indices, Smith and colleagues argued. To help fill the gap, they undertook a systematic review of non-disease-specific prognostic indices that aimed to predict all-cause mortality in older adults.
All told, they found 341 studies published between January 1987 and November 2011 that appeared to fit the bill; full-text review left 24 studies, of which 16 presented unique indices.
The 16 included six for community-dwelling adults, two for nursing home residents, and eight for older inpatients (five intended for use in the emergency department and three for use after discharge).
Smith and colleagues used the C statistic -- a measure of concordance -- to evaluate the discriminatory power of the indices.
By that measure, none had excellent discrimination (defined as a C statistic of 0.90 or greater) and three had very good discrimination (C of 0.80 to 0.89). The remaining studies had C-values of between 0.60 and 0.79, suggesting good to moderate discrimination.
On the other hand, most of the indices were well calibrated, with only two having a difference of greater than 10% between predicted and observed mortality.
None of the studies was free from potential bias, Smith and colleagues found, and only two had been validated by researchers not involved in the original development.
As well, none of the indices had been "prospectively tested and found to be accurate in a large diverse sample," they reported.
"Ultimately," they argued, "an index will be judged not only on its accuracy across diverse settings, but also on its clinical effect." However, only two small studies tested the effect of the indices on clinical outcomes.
The best evidence of a clinical effect, they said, would come from large randomized trials, which "have not been performed," they wrote.
The authors acknowledged some limitations to their own analysis: Their review excluded indices that estimated only relative risk or had not been validated; future research may find that some of these indices are generalizable and accurate, they pointed out.
Also, "our ability to assess publication bias was limited by our small sample size," they said.
"Ready access to critical prognostic information" will help doctors make better clinical decisions, commented Thomas Gill, MD, of Yale School of Medicine, in an accompanying editorial.
But he argued that prognostic indices based on mortality risk are not likely to be useful. Instead, researchers need to develop indices based on life expectancy, a process that will require well-designed studies, Gill suggested,
But "given the central role of prognosis in clinical decision making, waiting for the ideal index to be developed, validated, and rigorously tested would not be prudent," he argued.
In the meantime, Gill suggested, physician training should add more emphasis on prognosis in clinical decision making, including such factors as age-, sex-, and race-specific life expectancies, which can be calculated from standard life tables.
Primary source: Journal of the American Medical Association
Source reference: Yourman LC, et al "Prognostic indices for older adults: A Systematic Review" JAMA 2012; 307(2): 182-192.
Additional source: Journal of the American Medical Association
Source reference: Gill, TM "The central role of prognosis in clinical decision making" JAMA 2012; 307(2): 199-200.