Mean lifetime cost-effectiveness analysis (base-case analysis of 1000 early presenter patients aged 75 years)
| HEMS | GEMS | Incremental cost (95% CI) | Incremental QALYs gained (95% CI) | Incremental cost/QALY gained (ICER) | Incremental NMB @20K/QALY | Incremental NMB @30K/QALY | |||
| Mean cost (SE) | Mean QALYs gained (SE) | Mean cost (SE) | Mean QALYs gained (SE) | ||||||
| Deterministic analysis | £60 132 (£7) | 4.37 (0.00) | £56 328 (£6) | 4.24 (0.00) | £3804 (£3800 to £3810) | 0.14 (0.14 to 0.14) | £27 850 | −£1073 | +£294 |
| Probabilistic analysis | £60 743 (£319) | 4.40 (0.03) | £56 959 (£308) | 4.27 (0.03) | £3785 (£3700 to £3870) | 0.14 (0.13 to 0.15) | £28 027 | −£1084 | +£266 |
Incremental NMB is calculated by first assuming a WTP (£20 000 or £30 000/QALY gained), then converting health benefits (QALYs) into the common metric of GBP. The cost associated with each transport strategy is then subtracted, resulting in the net benefit of each strategy expressed in the monetary units. The difference between the two is the incremental NMB, negative values favour GEMS and positive values favour HEMS. NMB = (E * WTP) – C.
Costs are rounded to nearest whole number. QALYs are rounded to second decimal place.
C, cost; E, effectiveness; GBP, Pound sterling; GEMS, Ground Emergency Medical Services; GEMS, ground emergency medical services; HEMS, helicopter emergency medical services ; ICER, incremental cost-effectiveness ratio; NMB, net monetary benefit; QALYs, quality-adjusted life years; WTP, willingness-to-pay threshold.