Table 2 A summary of the parameters used in the model
From: An economic evaluation of triage tools for patients with suspected severe injuries in England
Clinical parameters | ||
Parameter | Value | Source |
Probability of patients having a transfer from a local hospital to an MTC if: | ||
They were a true positive (ISS ≥ 16 & tool positive) | 26.6% | Newgard et al 2016 [19] |
They were a false negative (ISS ≥ 16 & tool negative) | 32.5% | |
They were a true negative (ISS < 16 & tool negative) | 4.3% | |
They were a false positive (ISS < 16 & tool positive) | 7.4% | |
Probability of death within 30 days | Risk equation | TARN [15] |
Relative risk of death within 30 days of hospitalisation for patients with an ISS ≥ 16 who were treated at a local hospital | 1.25 | Newgard et al 2013 [3] |
Relative risk of death within 30 days of hospitalisation for patients with an ISS < 16 who were treated at a local hospital | 1 | Assumption |
Probability of death between 30 days post-injury and 1-year post-injury for patients with an ISS ≥ 16 | 3.6% | Mackenzie et al. 2006 [2] |
Relative risk of death between 30 days and 1 year post-hospitalisation for patients with an ISS ≥ 16 who were treated at an local hospital | 1.64 | |
Probability of death between 30 days post-injury and 1-year post-injury for patients with an ISS < 16 | 1.7% | Davidson et al 2011 [20] |
Probability of death after 1 year | Age and gender dependant | ONS [18] |
Hazard Ratio for the risk of death if someone has a suspected major trauma case with: | ||
An ISS of less than 16 | 1.38 | Newgard et al 2016 [14] |
An ISS of greater than or equal to 16 | 5.19 | Cameron et al. 2005 [4] |
Utility parameters | ||
Parameter | Value | Source |
Utility for patients with: | ||
An ISS of 16 or more | 0.65 | Ahmed et al [21] |
An ISS of 15 or less | 0.65 | |
General population utility | ||
Constant | 0.9508566 | Ara and Brazier [22] |
Age | − 0.0002587 | |
Age squared | −0.0000332 | |
Male (1 = male, 0 = otherwise) | 0.0212126 | |
Calculations | ||
Age and gender matched general population utility for the Ahmed et al population | 0.824 | Calculated. Mean age was 61 years and 59.1% of the analysis population was male in Ahmed et al. [21] |
Utility multipliers, relative to the utility in the general population, for patients with: | ||
An ISS of 16 or more | 0.789 | Calculated |
An ISS between 15 and 9 | 0.789 | Calculated |
An ISS of under 9 | 1 | We assumed that these patients would have a utility equal to that of the general population |
Cost Parameters | ||
Parameter | Value | Source |
Admission costs – base case | ||
Transfers between local hospitals and MTCs | £252 | Assumed to be one additional ambulance call out. NHS improvement [23]. Currency Code ASS02. |
MTC admission, if ISS is 16 or over | £2819 | NHS improvement [24] |
MTC admission, if ISS is less than 16 and over 8 | £1466 | |
Treatment of a patient with blunt trauma and an ISS in the range of: | ||
ISS ≤ 9 | £6198 | Christensen et al. [25] |
9 < ISS ≤ 16 | £8989 | |
16 < ISS ≤ 25 | £14,205 | |
ISS > 25 | £21,173 | |
Treatment of a patient with penetrating trauma and an ISS in the range of: | ||
ISS ≤ 9 | £6501 | Christensen et al. [26] |
9 < ISS ≤ 15 | £6035 | |
15 < ISS ≤ 24 | £9453 | |
24 < ISS ≤ 34 | £12,347 | |
ISS > 34 | £16,438 | |
Post discharge costs | ||
Cost between discharge and 6 months post treatment | £1766 | John Nichol, Personal communication |
Relative increase in lifetime treatment costs for patients with an ISS ≥ 16 compared to the general population | 1.45 | Cameron et al. 2006 [27] Delgado et al 2013 [28] |
Relative increase in lifetime treatment costs for patients with an ISS < 16 compared to the general population | 1.25 | Cameron et al. 2006 [27] Delgado et al 2013 [28] |
Yearly costs of NHS treatment | Age and gender dependent | Asaria 2017 [29] |