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Table 1 Epidemiological and quality of life (QALY) parameters of the economic model. We report the base case values and the standard deviations, taken either from the literature or from administrative data, the shapes of the prior distribution, the 95% CI from the posterior distribution of the parameters, and the source of the base case values

From: The impact of demographic changes, exogenous boosting and new vaccination policies on varicella and herpes zoster in Italy: a modelling and cost-effectiveness study

Parameter

Base case values

Standard deviations

Prior Distribution

95% CI Posterior distribution

Source

Epidemiological parameters

 Proportion of HZ cases developing PHNc

0.049 (by age)

0.0023 (by age)

Beta

[2]

 Hosp. rate for natural varicella (NV) per model TI/PI (per 1000 cases)

2.35/2.36 (by age)

0.61/0.62 (by age)

Beta

Estimatea

 Breakthrough varicella (BV) vs. NV hosp. rate

0.25

0.05

Beta

[0.16–0.35]

[58, 59]

 Hosp. rate for HZ per model TI/PI (per 1000 cases)

13.60/13.12 (by age)

4.49/4.63 (by age)

Beta

Estimatea

 Hosp. rate for PHN per model TI/PI (per 1000 cases)

41.55/40.77 (by age)

9.53/10.39 (by age)

Beta

Estimatea

 Case fatality rate for NV (per 1000 hospitalised)

4.01 (by age)

2.98 (by age)

Beta

Estimateb

 BV vs. NV case fatality rate

0.005

0.0022

Beta

[0.002–0.01]

[59, 60]

 HZ-PHN case fatality rate (per 1000 hospitalised)

12.70 (by age)

5.43 (by age)

Beta

Estimateb

 No. GP consultations per NV case

  < 14 years

2

0.2

Gamma

[1.63–2.43]

[59]

  ≥ 15 years

1

0.2

Gamma

[0.64–1.43]

[59]

 No. GP consultations per BV case

0.5

0.05

Gamma

[0.41–0.60]

[59]

Quality of life measures

 Overall weighted health state index (EQ-5Dindex)

0.84 (by age)

0.21 (by age)

Beta

 

[61]

 Weighted health state index varicella

  < 14 years

0.81

0.031

Beta

[0.76–0.86]

[31]

  ≥ 15 years

0.73

0.025

Beta

[0.68–0.78]

[62]

 Prob. severe NV cases

0.65

0.0063

Beta

[0.64–0.66]

[63]

 Prob. severe BV cases

0.25

0.011

Beta

[0.23–0.27]

[63]

 Reduction in QALY loss

 Mild vs. severe varicella cases

0.25

0.10

Beta

[0.08–0.47]

[48]

 QALY loss HZ

  20 years

0.022

0.0018

Beta

[0.019–0.026]

[48]

  40 years

0.031

0.0030

Beta

[0.026–0.037]

[48]

  60 years

0.064

0.0082

Beta

[0.049–0.081]

[48]

  80 years

0.19

0.030

Beta

[0.14–0.25]

[48]

  1. aAverage number of hospitalisations by age due to varicella, HZ, and PHN (Hospital Discharge Register, 2001–2012) divided by the predicted pre-vaccination incidence generated by the epidemiological model. PHN incidence is derived by multiplying the estimated HZ incidence by the probability of HZ cases developing PHN [2]
  2. bAverage number of deaths by age due to varicella (Italian National Health Institute, 2001–2012) and HZ (European Union detailed mortality database, 2001–2012) divided by the respective estimates of the hospitalisation rates
  3. cPHN cases lasting at least 3 months