Some of you may know Lewis Carroll’s classic nonsense poem “The hunting of the Snark”. Eight men set off with a blank map to find the mythical Snark.
And the Banker, inspired with a courage so new It was matter for general remark, Rushed madly ahead and was lost to their view In his zeal to discover the Snark
Snarks were dangerous creatures, however
“For, although common Snarks do no manner of harm, Yet, I feel it my duty to say, Some are Boojums—”
I dwell in a world where inspired by the new many have rushed on ahead to discover the SNARF (SigNals of Acute Renal Failure). The hunting of the SNARF has followed contours familiarly trodden and graphically illustrated by a Hype cycle(1).
It was kickstarted by new technologies called proteomics and genomics which gave the hope that soon would be discovered a rapid, accurate, and, most importantly, early biomarker of Acute Renal Failure (later renamed Acute Kidney Injury, AKI). This was the beginning of the hype that was driven in no small part by some fantastic early results. A paper published in the Lancet in 2005 was an important driver in the hype that followed(2). As with many early studies this involved children and cardiac surgery. Importantly the biomarker involved almost perfectly distinguished between those who had the disease and those who didn’t (ie not false negatives or false positives). As the field progressed and more and more studies were investigated across a more diverse range of patient groups and potential AKI causes the ability to discriminate between those with and without the disease became much more modest. It became apparent that one biomarker to rule them all was not going to be the solution – rather a panel of biomarkers whereby the clinician would choose which biomarkers, if any, to use according to the timing and suspected etiology of the renal injury, the baseline renal function and specific illness of the patient. We do not yet have such a panel, nor have we conducted sufficient investigations to find if an AKI biomarker(s) adds value to what the clinician can already deduce. That is partly my job and these are the greater challenges that must drive us up the slope of enlightenment to reach the plateau of productivity where finally we may capture the SNARF.
(1) Jackie Fenn, “When to Leap on the Hype Cycle,” Gartner Group, January 1, 1995
(2) Mishra J, Dent CL, Tarabishi R, et al. Neutrophil gelatinase-associated lipocalin (NGAL) as a biomarker for acute renal injury after cardiac surgery. Lancet 2005;365(9466):1231–8.