Table 3.
Model input parameters used in sponsor’s economic model
| Parameter | Value, range and distribution | Description |
|---|---|---|
| Clinical input parameters | ||
| Baseline CRBSI rate | 1.48 per 1000 catheter days; normal distribution; standard error = 0.074 (calculated in Excel sheet as mean divided by 20) | Source was data reported in Matching Michigan study, based on CRBSI rates reported in 97 % of English NHS ICUs [6] |
| Hazard ratio for CRBSI with Tegaderm CHG | 0.402; lognormal distribution; Alpha = −0.911 (calculated in Excel sheet as log mean); Beta = −0.393 (source unclear) | Source was the RCT identified in the sponsor’s clinical review [11], and hazard ratio was applied to CRBSI baseline risk |
| Baseline local site infection rate | 0.1 per patient; normal distribution; standard error = 0.01 (calculated in Excel sheet as mean divided by 10) | Source was a cost–benefit analysis identified in the sponsor’s cost-effectiveness review [28]. The original source was a small US RCT published in 1996 [34] |
| Hazard ratio for local site infection with Tegaderm CHG | 0.402; lognormal distribution; Alpha = −0.911 (calculated in Excel sheet as log mean); Beta = −0.393 (source unclear) | Assumed to be the same as the hazard ratio for CRBSI [11] and applied to baseline risk |
| Baseline dermatitis risk | 0.0026 per catheter; normal distribution; standard error = 0.00026 (calculated in Excel sheet as mean divided by 10) | Source was a cost–benefit analysis identified in the sponsor’s cost-effectiveness review [26]. The original source was the RCT by Timsit et al. comparing CHG sponge with standard dressings [12] |
| Relative risk for dermatitis with Tegaderm CHG | 4.4; lognormal distribution; Alpha = 18.034 (calculated in Excel sheet as log mean); Beta = −0.393 (source unclear) | Relative risk was taken from the RCT identified in the sponsor’s clinical review [11] and applied to the baseline risk |
| Cost and resource use input parameters | ||
| Cost of CRBSI | £9,990; Gamma distribution; Alpha = 198 (calculated in Excel sheet as mean divided by Beta); Beta = 50 (assumption) | Source was a 2008 health technology assessment identified in the sponsor’s cost-effectiveness review [25] and validated using expert advice by the sponsor |
| Cost of dermatitis | £150; Gamma distribution; Alpha = 30 (calculated in Excel sheet as mean divided by Beta); Beta = 5 (assumption) | Source was a cost–benefit analysis identified from the sponsor’s cost-effectiveness review [26]. The cost includes replacement of the catheter |
| Cost of local site infection | £250; Gamma distribution; Alpha = 50 (calculated in Excel sheet as mean divided by Beta); Beta = 5 (assumption) | Source was a study identified in the sponsor’s cost-effectiveness analysis [28]. The original source of the cost provided no additional information [39] |
| Cost of Tegaderm CHG | £6.21; value is fixed | Published price of the most commonly used size of dressing: 8.5 cm × 11.5 cm (catalogue number 1657R) |
| Cost of standard dressing | £1.34; value is fixed | The sponsor obtained this cost from their own prices for Tegaderm IV catalogue number 1635 |
| Number of days with catheter | 10 days; normal distribution; standard error = 2 days (calculated in Excel sheet as mean divided by 5) | Source was a study identified in the sponsor’s cost-effectiveness analysis [28]. The original source of the value provided no additional information [40] |
| Number of dressings | 3; normal distribution; standard error = 0.3 (calculated in Excel sheet as mean divided by 10) | Estimate was a conservative assumption based on to Tegaderm CHG Instructions for Use and expert opinion |
CHG chlorhexidine gluconate, CRBSI catheter-related bloodstream infection, ICU intensive care unit, NHS National Health Service, RCT randomised control trial