Cost-effectiveness of switching from trivalent to quadrivalent inactivated influenza vaccines for the at-risk population in Italy

Figures & data

Table 1. Health impact of switching from TIV to QIV for the targeted population in Italy during an average influenza season.

Age group	Non-consulting cases avoided	GP visits avoided	ED visits avoided	Hospitalizations avoided	Deaths avoided	Life years gained	QALYs gained	Work days saved
6 mo–4 y	20.5	29.9	0.3	0.5	0.0	0.0	0.4	—
5–19 y	75.5	112.0	0.5	0.7	0.0	0.2	1.8	720
20–49 y	306.8	454.9	2.2	3.2	0.6	14.6	21.4	6,734
50–64 y	414.8	615.3	2.2	18.4	2.7	50.2	55.4	9,110
≥ 65 y	1,583.5	2,256.9	77.2	423.7	129.8	819.5	783.0	—
Total	2,401	3,469	82	446	133	884	862	16,564

Abbreviations: ED, emergency department; GP, general practitioner; QALY, quality-adjusted life year; QIV, quadrivalent influenza vaccine; TIV, trivalent influenza vaccine

Table 2. Costs saved by switching from TIV to QIV for the targeted population in Italy during an average influenza season and incremental cost-effectiveness ratios.

	Costs saved					ICER (cost per QALY)
Age group	GP visits	ED visits	Hospitalisations	Medication	Lost productivity due to influenza	Payer perspective	Societal perspective
6 mo–4 y	€ 619	€ 69	€ 1,862	€ 444	€ 0	€ 110,083	€ 110,083
5–19 y	€ 2,314	€ 116	€ 2,593	€ 1,635	€ 87,252	€ 148,021	€ 99,295
20–49 y	€ 9,398	€ 523	€ 11,904	€ 6,647	€ 816,617	€ 95,564	€ 57,315
50–64 y	€ 12,713	€ 519	€ 67,986	€ 8,960	€ 1,104,659	€ 51,067	€ 31,126
≥ 65 y	€ 46,628	€ 18,612	€ 1,567,598	€ 35,873	€ 0	€ 19,170	€ 19,170
Total	€ 71,671	€ 19,839	€ 1,651,944	€ 53,559	€ 2,008,527	€ 23,426	€ 21,096

Abbreviations: ED, emergency department; GP, general practitioner; ICER, incremental cost-effectiveness ratio; QALY, quality adjusted life year; QIV, quadrivalent influenza vaccine; TIV, trivalent influenza vaccine

Figure 1. Deterministic sensitivity analysis (payer perspective). Abbreviations: ED, emergency department; GP, general practitioner; QALY, quality-adjusted life year; TIV, trivalent influenza vaccine.

Figure 2. Cost-effectiveness acceptability curve (payer perspective). Abbreviations: QALY, quality-adjusted life year; QIV, quadrivalent influenza vaccination.

Table 3. Input values.

			PSA^a
Model input	Baseline value	DSA range	Distribution type	Parameters
At-risk population in Italy, n
6 mo–4 y	213,555	—	—	—
5—19 y	1,000,788	—	—	—
20—49 y	4,449,039	—	—	—
50—64 y	6,277,505	—	—	—
≥ 65 y	13,369,754	—	—	—
Life expectancy, y
6 mo—4 y	80.46	—	—	—
5—19 y	70.63	—	—	—
20—49 y	47.02	—	—	—
50—64 y	27.73	—	—	—
≥ 65 y	12.59	—	—	—
Average yearly influenza-related GP visits for influenza per 100,000 individuals, n
6 mo—4 y	5512.5	±25%	Normal+ (µ,σ)	(1.00;0.05)
5—19 y	3975	±25%	Normal+ (µ,σ)	(1.00;0.05)
20—49 y	1725	±25%	Normal+ (µ,σ)	(1.00;0.05)
50—64 y	1725	±25%	Normal+ (µ,σ)	(1.00;0.05)
≥ 65 y	950	±25%	Normal+ (µ,σ)	(1.00;0.05)
Average yearly influenza-related ED visits per 100,000 individuals, n
6 mo—4 y	48.1	±25%	Normal+ (µ,σ)	(1.00;0.05)
5—19 y	15.2	±25%	Normal+ (µ,σ)	(1.00;0.05)
20—49 y	7.5	±25%	Normal+ (µ,σ)	(1.00;0.05)
50—64 y	5.5	±25%	Normal+ (µ,σ)	(1.00;0.05)
≥ 65 y	30.4	±25%	Normal+ (µ,σ)	(1.00;0.05)
Average yearly influenza-related hospitalizations per 100,000 individuals, n
6 mo—4 y	92.6	±25%	Normal+ (µ,σ)	(1.00;0.05)
5—19 y	24.9	±25%	Normal+ (µ,σ)	(1.00;0.05)
20—49 y	12.3	±25%	Normal+ (µ,σ)	(1.00;0.05)
50—64 y	52	±25%	Normal+ (µ,σ)	(1.00;0.05)
≥ 65 y	178.7	±25%	Normal+ (µ,σ)	(1.00;0.05)
Average yearly influenza-related deaths per 100,000 individuals, n
6 mo—4 y	0	±25%	Normal+ (µ,σ)	(1.00;0.05)
5—19 y	0.2	±25%	Normal+ (µ,σ)	(1.00;0.05)
20—49 y	2.1	±25%	Normal+ (µ,σ)	(1.00;0.05)
50—64 y	7.3	±25%	Normal+ (µ,σ)	(1.00;0.05)
≥ 65 y	55	±25%	Normal+ (µ,σ)	(1.00;0.05)
Utility for at-risk population
6 mo—4 y	0.95	—	Beta (α,β)	(−0.1543;−0.0081)
5—19 y	0.95	—	Beta (α,β)	(−0.1548;−0.0081)
20—49 y	0.942	—	Beta (α,β)	(−0.0059;−0.0004)
50—64 y	0.913	—	Beta (α,β)	(0.4791;0.0457)
≥ 65 y	0.872	—	Beta (α,β)	(1.1752;0.1724)
QALYs lost due to influenza, y
6 mo—4 y	0.0146	0.0110–0.0183	Beta (α,β)	(15.75;1063.13)
5—19 y	0.0146	0.0110–0.0183	Beta (α,β)	(15.75;1063.13)
20—49 y	0.0174	0.0131–0.0218	Beta (α,β)	(15.70;886.83)
50—64 y	0.0174	0.0131–0.0218	Beta (α,β)	(15.70;886.83)
≥ 65 y	0.0293	0.0220–0.0366	Beta (α,β)	(15.50;513.57)
Influenza vaccination coverage, %
6 mo—4 y	9.66	7.25–12.08	Beta (α,β)	(14.35;134.27)
5—19 y	10.86	8.15–13.58	Beta (α,β)	(14.15;116.17)
20—49 y	18.60	13.95–23.25	Beta (α,β)	(12.83;56.18)
50—64 y	18.60	13.95–23.25	Beta (α,β)	(12.83;56.18)
≥ 65 y	49.90	37.43–62.38	Beta (α,β)	(7.51;7.54)
Proportion of influenza cases requiring medical consultation, %
6 mo—4 y	59.58	44.69–74.48	Beta (α,β)	(5.8714;3.9832)
5—19 y	59.82	44.87–74.78	Beta (α,β)	(5.8306;3.9163)
20—49 y	59.84	44.88–74.80	Beta (α,β)	(5.8275;3.9113)
50—64 y	59.82	44.87–74.78	Beta (α,β)	(5.8306;3.9163)
≥ 65 y	59.58	44.69–74.48	Beta (α,β)	(5.8714;3.9832)
Mean daily per-person productivity (€)
6 mo—4 y	0.00	—	—	—
5—19 y	121.26	—	—	—
20—49 y	121.26	—	—	—
50—64 y	121.26	—	—	—
≥ 65 y	0.00	—	—	—
Cost of resources used (€)
GP visits	20.66	15.50–25.83	Gamma (µ,σ)	(20.66;2.64)
ED visits	241.00	180.75–301.25	Gamma (µ,σ)	(241.00;30.74)
Hospitalization	3.700.00	2775.00–4625.00	Gamma (µ,σ)	(3700.00;471.94)
Vaccine cost (€)
TIV	5.39^b	—	—	—
QIV	11.08^b	—	—	—
Medication costs (€)
GP consultation	12.40	—	Gamma (µ,σ)	(12.40;1.58)
ED consultation	40.74	—	Gamma (µ,σ)	(40.74;5.20)
No consultation	3.00	—	Gamma (µ,σ)	(3.00;0.38)
Lost workdays due to medical consultation for influenza
6 mo—4 y	0.00
5—19 y	0.26	—	—	—
20—49 y	0.26	—	—	—
50—64 y	0.26	—	—	—
≥ 65 y	0.00
Employment rate (%)
6 mo—4 y	0.0	—	—	—
5—19 y	15.6	—	—	—
20—49 y	60.5	—	—	—
50—64 y	48.2	—	—	—
≥ 65 y	0.0	—	—	—
Working hours per week
6 mo—4 y	0.0	—	—	—
5—19 y	36.0	—	—	—
20—49 y	36.0	—	—	—
50—64 y	36.0	—	—	—
≥ 65 y	0.0	—	—	—
Discount rate	0.03	0.00—0.05	—	—
Relative circulating level of B strain vs. total influenza, %
2003—2004	1.00	0.75—1.25	Beta (α,β)	(15.83;1567.17)
2004—2005	16.50	12.38—20.63	Beta (α,β)	(13.19;66.77)
2005—2006	59.80	44.85—74.75	Beta (α,β)	(5.83;3.92)
2006—2007	2.10	1.58—2.63	Beta (α,β)	(15.64;729.26)
2007—2008	38.60	28.95—48.25	Beta (α,β)	(9.43;15.01)
2008—2009	16.90	12.68—21.13	Beta (α,β)	(13.12;64.54)
2010—2011	1.30	0.98—1.63	Beta (α,β)	(15.77;1197.99)
2011—2012	28.80	21.60—36.00	Beta (α,β)	(11.10;27.45)
2012—2013	38.80	29.10—48.50	Beta (α,β)	(9.40;14.83)

Abbreviations: DSA, deterministic sensitivity analysis; ED, emergency department; GP, general practitioner; Normal+, normal positive; PSA, probabilistic sensitivity analysis; QALY, quality-adjusted life year; SD, standard deviation.

^a For positive normal distribution, simulation values < 0 were assigned a value of 0. Beta distributions show their (α,β) parameterisation, where α = number of success, β = number of failures.

^b This price corresponds to the ex-factory price per dose negotiated by the Italian Agency for Medicines. In Italy, the vaccination programme is financed at the regional level, and local health agencies obtain the vaccine at a different price for each region. For this analysis, prices were as reported in a recent Italian analysis.¹¹

Table 4. Influenza vaccine effectiveness for trivalent influenza vaccine in at-risk individuals for A strains and matched and mismatched B lineage strains.

Age group	A(H1N1)^a	A(H3N2)^a	Matched B^b	Mismatched B^b
6 mo – 4 y	59.0%	59.0%	66.0%	44.0%
5 – 19 y	59.0%	59.0%	66.0%	44.0%
20 – 49 y	61.0%	61.0%	77.0%	52.0%
50 – 64 y	61.0%	61.0%	73.0%	49.0%
≥ 65 y	58.0%	58.0%	66.0%	44.0%

^a From Uhart et al.¹² Influenza vaccine effectiveness was assumed to be the same for each A strain.

^b From Tricco et al.³³

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