Table 4.

One-way sensitivity analysis scenarios showing whether gene therapy is cost-effective vs on-demand and prophylaxis FIX replacement upon changing 1 parameter at a time

VariationsNo.Altered parameterOn-demandProphylaxisGene therapy
Standard half-life FIXExtended half-life FIXStandard half-life FIXExtended half-life FIXStandard half-life FIXExtended half-life FIX
(Approach A)(Approach B)(Approach C)(Approach D)(Approach E)(Approach F)
Gene therapy effectiveness in IU/dL 1 Starting level 34, annual decrement 0     Reference 
2 Starting level 34, annual decrement 2, switch at 3  $262 930   Reference $9 046 671 
3 Starting level 23, annual decrement 1, switch at 3  $126 952   Reference $9 180 457 
4 Starting level 23, annual decrement 2, switch at 3 $100 274 $488 374   Reference $8 568 882 
5 Starting level 34, annual decrement 1, switch at 15  $140 009   Reference $9 605 377 
6 Starting level 34, annual decrement 2, switch at 15 $109 567 $499 266   Reference $8 665 383 
7 Starting level 23, annual decrement 1, switch at 15 $176 396 $573 397   Reference $8 635 833 
8 Starting level 23, annual decrement 2, switch at 15 $372 979 $792 777 $85 731 $19 939 915 Reference $8 564 752 
Cost in USD 9 Cost of gene therapy: Manufacturing cost     Reference $25 560 300 
10 Cost of gene therapy: $1 000 000     Reference $25 560 300 
11 Cost of gene therapy: $3 000 000     Reference $25 560 300 
12 Cost of FIX: 20% of wholesale acquisition cost $35 486 $116 709   Reference $4 481 850 
Age at infusion 13 Age at infusion: 25 y     Reference $15 555 425 
14 Age at infusion: 45 y  $379 654   Reference $14 020 363 
15 Age at infusion: 65 y $268 118 $682 517  $25 729 958 Reference $10 851 282 
Failure rate 16 Post–gene therapy infusion failure rate 2%     Reference $22 117 700 
17 Post–gene therapy infusion failure rate 5%     Reference $17 583 486 
VariationsNo.Altered parameterOn-demandProphylaxisGene therapy
Standard half-life FIXExtended half-life FIXStandard half-life FIXExtended half-life FIXStandard half-life FIXExtended half-life FIX
(Approach A)(Approach B)(Approach C)(Approach D)(Approach E)(Approach F)
Gene therapy effectiveness in IU/dL 1 Starting level 34, annual decrement 0     Reference 
2 Starting level 34, annual decrement 2, switch at 3  $262 930   Reference $9 046 671 
3 Starting level 23, annual decrement 1, switch at 3  $126 952   Reference $9 180 457 
4 Starting level 23, annual decrement 2, switch at 3 $100 274 $488 374   Reference $8 568 882 
5 Starting level 34, annual decrement 1, switch at 15  $140 009   Reference $9 605 377 
6 Starting level 34, annual decrement 2, switch at 15 $109 567 $499 266   Reference $8 665 383 
7 Starting level 23, annual decrement 1, switch at 15 $176 396 $573 397   Reference $8 635 833 
8 Starting level 23, annual decrement 2, switch at 15 $372 979 $792 777 $85 731 $19 939 915 Reference $8 564 752 
Cost in USD 9 Cost of gene therapy: Manufacturing cost     Reference $25 560 300 
10 Cost of gene therapy: $1 000 000     Reference $25 560 300 
11 Cost of gene therapy: $3 000 000     Reference $25 560 300 
12 Cost of FIX: 20% of wholesale acquisition cost $35 486 $116 709   Reference $4 481 850 
Age at infusion 13 Age at infusion: 25 y     Reference $15 555 425 
14 Age at infusion: 45 y  $379 654   Reference $14 020 363 
15 Age at infusion: 65 y $268 118 $682 517  $25 729 958 Reference $10 851 282 
Failure rate 16 Post–gene therapy infusion failure rate 2%     Reference $22 117 700 
17 Post–gene therapy infusion failure rate 5%     Reference $17 583 486 

▪ Gene therapy approach with the lower cost per QALY was used as the reference and compared to the 5 other approaches.

▪ Gene therapy reference treatment approach is dominant (less costly and yields more QALYs).

▪ Gene therapy reference treatment approach is more costly but remained cost-effective considering a $150 000/QALY threshold.

▪ Gene therapy reference treatment approach is not cost-effective considering a $150 000/QALY threshold.

▪ Gene therapy reference treatment approach yields less QALYs but remains cost-effective considering a $150 000/QALY threshold.

Detailed results are presented in supplemental Table 14.

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