James Min and colleagues followed 422 patients who had normal (CAC=0) calcium scans and asked the question: “What is the ‘warranty period’ for remaining normal”? The study, along with a provocative editorial by Harvey Hecht, appears in the March 16 issue of JACC.
Following their initial scans, study subjects then received annual calcium scans. Over the course of five years, 25% of the subjects went on to “convert” to a calcium score greater than zero. “Incidence of conversion to CAC > 0 was nonlinear and was highest in the fifth year,” the authors noted. They were unable to identify clinical factors that would trigger earlier calcium re-tests.
An accompanying editorial comment by Harvey Hecht makes some startling claims. Hecht first dismisses criticism of calcium scans based on the lack of outcome data, citing “the misconception that CAC is a treatment modality” and noting that “outcome studies have never been required” for other cardiac diagnostic modalities or for the Framingham risk score. More widespread use of calcium scans has been held back because of “the selective demand” for outcome studies, “with a resultant loss of life,” writes Hecht.
Hecht argues that clinical trials of calcium scans are meaningless:
Randomized controlled trials are not necessary to prove that treatment of high-risk patients saves lives. If a randomized controlled trial were performed and failed to show that treatment of CAC-identified high-risk patients saved more lives, the fault would lie with the treatment rather than the test.
Hecht then flips things around and argues that clinical trials are necessary to justify drug intervention in patients with zero calcium scores who would otherwise be classified as intermediate risk. Responding, perhaps, to past critiques of the cost-effictiveness of calcium screening, Hecht again flips conventional logic and writes that “the cost savings implicit in the decreased prescription drug use during the 4-year warranty period are relatively straightforward and of great magnitude. In addition, there would be significant savings by eliminating stress testing for risk evaluation in asymptomatic patients with multiple risk factors.”
Hecht foresees an “exponential increase” in calcium scanning as the technique gains “insurance, legislative, and professional society endorsement.” Hecht concludes: “the cost of overtreatment in this lowest-risk asymptomatic population is quite high; CAC = 0 is priceless.”
George Diamond told CardioBrief that he objects strongly to the editorial:
I am no fan of the “warranty” concept… Note here that the warranty extends only to CAC, not to events, and that the conversions follow a logarithmic growth curve identical to that for most biological processes. A plot of log(conversion) vs time would therefore be linear with NO unique warranty time.
Finally the “priceless” metaphor is a highly misleading marketing gambit. The test costs a not inconsequential amount of money (usually not covered by insurance) and carries a complex increment of risk (part of which derives from radiation exposure and part of which derives from potential undertreatment of conventional risk factors such as hyperlipidemia and hypertension). Only the lawyers and physician-providers would consider this “priceless.”
Study finds significant lesions in one-fifth of patients with zero calcium scores
If not a warranty, how about a money back policy. I had a calcium score of zero and one year later got 3 stents. The $250 would go nicely towards my $4000 co-pay for my intervention.