Our paper, “Cystatin C: A Promising Test for Insurance Screening,” was published in early 2009. At that time, most studies about this test were focused solely on its role as a novel kidney disease marker.
In the interim, several hundred new studies have greatly expand- ed our knowledge about cystatin C in a broad range of contexts. For this reason, a new comprehensive literature review is needed if we are to understand the true underwriting implications of this test.
This review of the world literature on cystatin C, a novel marker for renal impairment, encompasses all relevant studies published up to the end of November, 2008. It was undertaken to contribute to essential efforts aimed at replacing conventional screening practices, most notably the deployment of chest x-rays, treadmill stress tests and resting ECGs. For a variety of reasons, these entities are no longer appropriate choices for routine use in underwriting.
This literature review demonstrates clearly that cystatin C is superior to creatinine and creatinine-based eGFR equations as an indicator of mild-to-moderate impairment of kidney function. It further reveals that cystatin C is an independent marker for the risk of cardiovascular disease, potentially synergistic with NT-proBNP as a screening duo at older ages. Moreover, cystatin C may confer additional risk assessment advantages in terms of premature physical frailty, early cognitive impairment and assessing the severity of liver disease.
There do not appear to be any significant impediments to the deployment of cystatin C in risk appraisal. Therefore, in consideration of the foregoing, it is this author’s opinion that cystatin C should now be further evaluated for deployment as both a screening and reflexive test in mortality and morbidity risk underwriting.