Table 1 Inputs of the decision model for the evaluation of IVIG for severe sepsis/septic shock: parameter values and uncertainty over parameter values
Parameter | Source | Base case | Notes on scenario analyses undertaken | Notes on subgroup analyses |
|---|---|---|---|---|
Cohort characteristics | Â | Â | Â | Â |
Mean age of a severe sepsis patient at admission to hospital | CMPD | 63Â years old | Same as base case | Assumed to vary in subgroups defined using age. Sourced from ICNARC database |
Proportion of males in a severe sepsis population at admission to hospital | CMPD | 0.53 | Same as base case | Assumed to vary in subgroups defined using gender. Sourced from CMPD |
Short-term outcomes (ST) | Â | Â | Â | Â |
Probability of dying in hospital when SC is used in the treatment of severe sepsis (baseline risk) | CMPD | 40.6%, 95% CI (40%, 41.2%) | Same as base case | Assumed to vary per subgroup (all). Sourced from CMPD |
Odds ratio, when IVIG is used to complement SC in the treatment of severe sepsis (based on Model M1) | Evidence synthesis (‘Clinical effectiveness of IVIG’) | 0.75 , 95% CI (0.58, 0.96) | Alternative models tested; see Table 2 | Same as base case |
Longer-term outcomes (LT) | Â | Â | Â | Â |
Age specific probability of dying in yearly intervals, conditional on patients having survived up to the start of the year. | Cuthbertson database and general population life tables 2010 | Figure 4. Varies with time. | (1) time horizon | Assumed to vary for subgroups defined using age and APACHE II score. Sourced from CMPD |
(2) time points at which patients reverted to survival of general population | ||||
Cost-related parameters | Â | Â | Â | Â |
Costs of overall IVIG therapy | Non-stochastic, BNF | £5,539.05 | Same as base case | Same as base case |
Costs of SC, when only SC is used in the treatment of severe sepsis | Non-stochastic, | £0 | Same as base case | Same as base case |
LOS in ICU for patients remaining alive until discharge from hospital | CMPD | 8.48 (SE = 0.086) | Same as base case | Assumed to vary for all subgroups. Sourced from CMPD |
LOS in ICU for patients dying in hospital | CMPD | 7.40 (SE = 0.108) | Same as base case | Assumed to vary for all subgroups. Sourced from CMPD |
Costs associated to a day in ICU for a patient with severe sepsis | Non-stochastic, reference costs [24] | £1,393 | Same as base case | Same as base case |
Overall hospital LOS for patients remaining alive until discharge from hospital | CMPD | 21.29 (SE = 0.292) | Same as base case | Assumed to vary for all subgroups. Sourced from CMPD |
Overall hospital LOS for patients dying in hospital | CMPD | 39.07 (SE = 0.325) | Same as base case | Assumed to vary for all subgroups. Sourced from CMPD |
Costs associated to a day in wards other than ICU for a patient with a severe sepsis episode | Non-stochastic, reference costs [24] | £196 | Same as base case | Same as base case |
Costs incurred between year t-1 and year t after hospital discharge | Manns [25] | t = 1: £13,654 and t >1: £4,466.5/year | (1) ± 50% of Manns’ estimates | Same as base case |
(2) average annual per capital NHS cost for the general population | ||||
Utilities | Â | Â | Â | Â |
In-hospital HRQoL weight associated to severe sepsis patients | Drabinsky [26] | 0.53 | Same as base case | Same as base case |
HRQoL weight associated to severe sepsis patients at year t | Cuthbertson database, Drabinsky [26] | t = 1: 0.62 and t >1: 0.6833 | Same as base case | Same as base case |