Table 4.
Model input parameters used in EAC’s update of the sponsor’s economic model
| Variable | EAC point estimate | Source | EAC range and source |
|---|---|---|---|
| Baseline CRBSI rate | English data (2010): 1.48 per 1000 catheter days Scottish data (2013): 0.3 per 1000 catheter days |
Bion et al. [6] Scottish ICU report [36] |
DSA: range = 0.2–1.75, lower CI from Scotland and upper CI from Bion et al. [6, 36] PSA: Gamma distribution. The PSA was run twice, with English data and more recent Scottish data Range = 1.28–1.75, 95 % CI from Bion et al. [6] Range = 0.2–0.6, 95 % CI from Scotland [36] |
| Hazard ratio for CRBSI with Tegaderm CHG | 0.402 | Timsit et al. [11] | DSA: range is equal to 95 % CI of 0.186–0.868 PSA: lognormal distribution, with range equal to 95 % CI of 0.186–0.868 [11] |
| Baseline local site infection rate | 0.14 per 1000 catheter days | NHS Wales 2013 data [33] | DSA: a range of 0–0.3 infections per 1000 catheter days PSA: Gamma distribution, with an SE of 0.1 |
| Hazard ratio for local site infection with Tegaderm CHG | 0.402 | Assumed to be equal to hazard ratio for CRBSI from Timsit et al. [11] | DSA: range equal to 95 % CI of 0.186–0.868 PSA: lognormal distribution, with range equal to 95 % CI of 0.186–0.868 [11] |
| Baseline dermatitis probability | 0.0021 | Timsit et al. [11] | DSA: a range of 0–0.01 PSA: Beta distribution was used, with Alpha = 1 and Beta = 475 [11] |
| Risk reduction for dermatitis with Tegaderm CHG | 1 | Timsit et al. [11] | DSA: a range of ± 100 % (0–2) PSA: lognormal distribution, with an SE of 0.5 |
| Cost of CRBSI | £9990 | Hockenhull et al. [25] | DSA: a range of ± 50 % (£4950–14,850) PSA: Gamma distribution, with an SE of £3000 |
| Cost of dermatitis | £6 | Expert advice | DSA: a range of ± 30 % (£4.10–7.80) PSA: Gamma distribution, with an SE of £3 |
| Cost of local site infection | £100 | Expert advice | DSA: a range of ± 30 % (£70–130) PSA: Gamma distribution, with an SE of £30 |
| Number of days with catheter (catheter dwell time) | 10 days | Expert advice confirmation of Ho and Litton [40] | DSA: a range of ± 50 % (5–15 days) PSA: Gamma distribution, with an SE of 5 days |
| Number of dressings | 3 | Assumption (based on change of dressing every 3–7 days) | DSA: a range of ± 66 % (1–5 dressings) PSA: Gamma distribution, with an SE of 2 dressings |
| Cost of Tegaderm CHG | £6.26 | NHS Supply Chain. Weighted average of dressing sizes [35] | This is fixed and not included in either the deterministic or probabilistic analyses |
| Cost of standard dressing | £1.54 | NHS Supply Chain. Weighted average of brands [35] | This is fixed and not included in either the deterministic or probabilistic analyses |
CHG chlorhexidine gluconate, CRBSI catheter-related bloodstream infection, CI confidence interval, DSA deterministic sensitivity analysis, EAC External Assessment Centre, ICU intensive care unit, NHS National Health Service, PSA probabilistic sensitivity analysis, SE standard error