“Those studies yielded some of the most robust clinical data on endoscopic sinus surgery in the last decade,” said Dr. Smith, who participated in the NIH trials. “So we’re confident that they gave us a strong foundation for extrapolating cost effectiveness—and this is key—over a long enough time horizon to really give policymakers and payers something to think about.”
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November 2014Looking at a reference case of refractory CRS, the investigators found that the sinus surgery strategy cost $48,838.38 and produced 20.50 QALYs. The medical therapy alone strategy, in contrast, cost $28,948.98 and produced 17.13 QALYs.
But those figures don’t tell the whole story, according to Dr. Rudmik, who is an assistant professor in the division of otolaryngology–head and neck surgery at the University of Calgary in Alberta, Canada. “You have to evaluate the ICER calculation to fully appreciate the cost effectiveness.” The ICER, he explained, “gives you the additional cost in relation to the additional benefit of the interventions you’re evaluating in an economic model.”
In this case, he noted, the ICER for the ESS strategy versus medical therapy alone strategy was $5,901 per QALY for the reference case. Although that number understandably increased when more complicated cases were factored in, even then, “ESS remained the most cost-effective decision, with a maximum ICER of $11,030 per QALY.” At this point, clinicians who don’t have a Master of Science degree in health economics may be thinking, “Are we done yet?” But Dr. Rudmik stressed that one more important statistical tool needs to be understood in order to grasp the significance of his cost-effectiveness model—it’s known as a probabilistic sensitivity analysis, a calculation “that gives you a percent certainty that an intervention is cost effective below a certain willingness to pay [WTP] threshold,” he said. “That is, what dollar expenditure is a government or private payer comfortable with, when it comes to paying for an intervention based on the expected long-term benefits?”
What is considered an acceptable WTP threshold? “We focused on a threshold of $50,000 per QALY, because most policymakers in the U.S. will accept a medical intervention that is below that threshold,” Dr. Rudmik said. And, here again, the study results favored the ESS strategy. The investigators found that there is a 74.5% and 77.8% certainty that sinus surgery is the most cost-effective strategy for managing refractory CRS, at a WTP threshold of $25,000 and $50,000 per QALY, respectively. Importantly, the “time horizon” analysis done in the study suggested that these cost-effectiveness thresholds began to kick in at three years of follow-up.