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Compared with common care, gene therapy for sickle cell disease (SCD) would likely be cost-effective if its price was below $2 million, according to a comparative modeling analysis.

At an assumed $2 million price tag for gene therapy, the incremental cost-effectiveness ratio (ICER) for gene therapy versus common care using the University of Washington Model for Economic Analysis of Sickle Cell Cure (UW-MEASURE) simulation model was $193,000 per quality-adjusted life year (QALY), while the ICER using the Fred Hutchinson Institute Sickle Cell Disease Outcomes Research and Economics Model (FH-HISCORE) was $427,000 per QALY, under the healthcare sector perspective, reported Anirban Basu, PhD, of the University of Washington in Seattle, and colleagues.

Under the societal perspective, the UW-MEASURE estimated an ICER of $126,000 per QALY and the FH-HISCORE estimated an ICER of $281,000 per QALY with gene therapy compared with common care, which included use of hydroxyurea and transfusions but excluded use of any other disease-modifying therapies or hematopoietic transplants, they noted in the .

"The difference in results between models stemmed primarily from considering a slightly different target population and incorporating the quality-of-life (QOL) effects of splenic sequestration, priapism, and acute chest syndrome in the UW model," the authors wrote.

Both models predicted that much of gene therapy's value in SCD will be the reduction in the lifetime number of acute pain crises -- reductions likely to help "offset the high upfront administration costs of gene therapy, greatly improve patients' prospects for long-term employment, decrease or possibly eliminate caregiver burden, and substantially improve recipients' life expectancy and recipients' and caregivers' QOL," Basu and colleagues observed.

Accounting for uncertainty, "there was a a high (>95%) probability of acceptability in the UW-MEASURE for a gene therapy price of $2 million when using equity-informed thresholds," the authors wrote, with that confidence level of acceptability declining above an acquisition cost of $2.5 million.

Though the FH-HISCORE found that any price below $1 million should be acceptable, Basu told 番茄社区, "above $1 million and the acceptability decreases quite suddenly."

Basu and team applied the two independently developed simulation models to Centers for Medicare & Medicaid Services claims data from 2008 to 2016 in order to estimate costs and outcomes over a lifetime with and without gene therapy from both healthcare sector and societal perspectives.

They noted that gene therapy is less likely to be cost-effective at a price of $2 million from a healthcare sector perspective compared with the broader societal perspective in both models.

"Unlike many other chronic conditions, SCD affects persons from an early age, such that their and their caregivers' life trajectories are dramatically different from those of peers without SCD," they wrote. "As such, from a societal perspective, both models show higher likelihood that the treatments will be cost-effective."

Basu noted that "this is one of the most comprehensive valuations of any therapy -- especially a gene therapy -- that's published to date."

"When I say comprehensive, it not only captures the real-world experiences of patients in terms of what they experience and their comorbidities, but it included a lot of other outcomes, not just the cost of their healthcare, but productivity loss, income loss, time-use cost, and caregiver burden," he said. "It really covered a whole host of different attributes that entered into the value calculation."

However, he added that, as with most modeling studies, this one comes with limitations. For example, he pointed out that both models assume the durability of gene therapy will persist over the lifetime of the patients.

In their paper, Basu and colleagues wrote that "this issue is particularly important because only one gene therapy trial has reported outcomes, with a median follow-up of 17.3 months. As longer-term follow-up results are presented for more patients in the early trials, and results from different gene therapies are reported, it will be important to compare results predicted here with those observed and reevaluate value as needed."

While the study showed that gene therapy is cost-effective if its price comes in under $2 million, "that doesn't mean it will be affordable," Basu warned.

"We are going to see a deluge of gene therapies coming into the market over the next 10 years, and this will bring tremendous benefit to patients," he said. "But, whoever is going to pay for this gene therapy also needs to understand how they can negotiate prices to make sure the patients are getting this novel therapy, and that the overall healthcare system can afford it long term."

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