Cost-effectiveness of somatrogon in the Spanish pediatric population with growth hormone deficiency

Figures & data

Figure 1. Markov model scheme.

Table 1. Main assumptions of the economic model.

Concept	Assumption	Validation References
Efficacy	The same efficacy is considered for all GH administered daily.	Experts panel
Mortality	The state of death is not considered, since the modeled time horizon ends at 18 years of age, with reduced mortality, also taking into account that GHD is not associated with excess mortality compared to the general population.	Experts panel
Abandonment of treatment	Abandonment of treatment in the first year is not considered because it is irrelevant.	Experts panel
Treatment adherence	Assumed 5% higher with weekly injection compared to daily injection (Table S1).	Experts panel [19]
Treatment adherence	It is estimated that this increase in adherence due to the weekly versus daily GH regimen would not be reduced over time.	Experts panel
Adherence to daily GH	Adherence up to 10 years is assumed based on the studies by Maggio (2018) and Rodríguez-Arnao (2019).	Experts panel [15,16]
Growth rate	With somatrogon (Table S2) an GH-d (Table S3).	Experts panel
Somatrogon dose	0.66 mg/kg/week	SmPC dose [20]
GH-d dose	Average: 0.21 mg/kg/week Minimum: 0.175 mg/kg/week Maximum: 0.245 mg/kg/week	Experts panel [9]
Cost per mg	GH-d: 17.50 € Somatrogon: 5.59 € (excluding 4% discount in the base case)	[21] *
GH-d market shares	Genotonom®: 22.24% Norditropin®: 4.69% Saizen®: 24.25% Humatrope®: 12.49% Nutropin AQ®: 6.75% Zomacton®: 1.77% Omnitrope®: 27.81%	IQVIA
Product losses	Not considered.	Experts panel
Monitorization cost	See Table S4.	Experts panel [22]
Utilities	Utilities according to height (Table S5).	[23]
Utilities	Additional utility of weekly versus daily injection: 0.02 ± 0.01	[24]

*Note: The calculation of the cost of €/mg of Somatrogon equivalent to €/mg of Somatropin, has been carried out taking into account the average dose of the posology recommended in the Technical Data Sheet of the GH-d indication. SmPC: Summary of Product Characteristics.

Table 2. Efficacy result of clinical trial with somatrogon [26].

Ítem	Somatrogon	Genotropin
Treatment	Somatrogon weekly subcutaneous injection	GH daily injection
Number of patients analyzed	109	115
Annual growth rate (cm) Mean (95% CI)	10.10 (9.58–10.63)	9.78 (9.29–10.26)

Table 3. Result of the deterministic base case.

	Somatrogon	GH-d	Difference
Cost-effectiveness
Cost Administered drugs Monitorization Total	66,383 € 6,292 € 72,675 €	59,912 € 6,292 € 66,204 €	6,471 € 0 € 6,471 €
Height (cm) – end of treatment	170.28	166.17	4.11
Cost per cm gained with the most effective treatment			1,574 €
Cost-utility
Cost Administered drugs Monitorization Total	66,383 € 6,292 € 72,675 €	59,912 € 6,292 € 66,204 €	6,471 € 0 € 6,471 €
QALY	7.455	7.119	0.336
Cost per QALY gained with the most effective treatment			19,259 €

QALY: quality-adjusted life years; GH-d: growth hormone (somatropin) daily.

Table 4. Univariate sensitivity analysis.

Analysis	Parameter	Minimum value	Maximum value	Lower limit INMB	Uper limit INMB
1	Somatrogon: unit cost (per device/cartridge) − 60 mg	272.89 €	404.25 €	11,376 €	−8,506 €
2	Additional utility of weekly injection versus daily injection	0.00	0.05	−1,990 €	8,654 €
3	Somatrogon: unit cost (per device/cartridge) − 24 mg	109.16 €	161.70 €	4,826 €	−1,291 €
4	Omnitrope®: unit cost (per device/cartridge) − 10 mg	142.39 €	210.93 €	172 €	3,836 €
5	Saizen®: unit cost (per device/cartridge) − 5 mg	71.19 €	105.46 €	575 €	3,391 €
6	Saizen®: unit cost (per device/cartridge) − 8,8 mg	113.91 €	168.74 €	575 €	3,391 €
7	Genotonorm®: unit cost (per device/cartridge) − 12 mg	170.86 €	253.11 €	804 €	3,140 €
8	Annual discount rate for life years and QALYs	0%	5%	3,379 €	1,119 €
9	Nutropin AQ®: unit cost (per device/cartridge) − 10 mg	142.39 €	210.93 €	875 €	3,062 €
10	Annual cost discount rate	0%	5%	624 €	2,612 €
11	Height Utility – HtSDS Score from −1.5 to −1	0.82	0.85	2,921 €	944 €
12	Genotonorm® MiniQuick: unit cost (per device/cartridge) (2 mg, pre-filled syringe)	28.48 €	42.19 €	1,101 €	2,812 €
13	Height Utility – HtSDS Score from −1 to −0.5	0.84	0.86	1,097 €	2,707 €
14	Genotonorm®: unit cost (per device/cartridge) − 5 mg	71.19 €	105.46 €	1,161 €	2,746 €
15	Humatrope®: unit cost (per device/cartridge) − 6 mg	85.43 €	126.56 €	1,274 €	2,622 €

INMB: incremental monetary net benefit. A positive BNMI indicates that somatrogon is cost-effective compared to GH-d (Omnitrope, Saizen, Genonorm, Nutropinac, Humatrope). A negative BNMI indicates the opposite.

Figure 2. Cost-effectiveness plane of the probabilistic analysis. Weekly somatrogon vs. GH-d.

QALYs: quality-adjusted life years; GH-d: growth hormone (somatropin) daily.

Figure 3. Acceptability curves of the probabilistic analysis. Weekly somatrogon vs. GH-d.

GH-d: growth hormone (somatropin) daily.; WTP: willingness to pay.

Table 5. Probabilistic analysis result.

	Mean	95% CI
Cost-effectiveness
Cost differences	6,592 €	6,235 €; 6,949 €
cm differences	4.10	4.08; 4.12
Cost per cm gained	1,608 €	1,528; 1,686 €
Cost-utility
Cost differences	6,592 €	6,235 €; 6,949 €
QALY difference	0.333	0.326; 0.340
Cost per QALY gained	19,796 €	19,126; 20438 €

*For a willingness to pay of €25,000 per QALY gained.

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