Table 4.

Scenarios* of different structural model parameters (mean per 100 000 persons) by strategy

	Costs (£ millions)			QALYs			Primary prevention versus early detection		Primary prevention versus no intvn
	Early detection	Primary prevention	No intvn	Early detection	Primary prevention	No intvn	Incremental cost (£m)	Incremental QALYs	Incremental cost (£m)	Incremental QALYs
Base case (30 years duration, age 50, 3% discounting costs & QALYs)	493.5	386.4	406.1	1 821 195	1 822 937	1 821 201	−107.1	1742	−19.7	1736
Duration of model
10 years	166.5	113.6	121.3	860 698	860 985	860 726	−52.9	287	−7.7	259
20 years	327.5	240.5	256.0	1 453 667	1 454 612	1 453 701	−87.0	945	−15.5	910
40 years	639.4	522.9	544.3	2 003 133	2 005 477	2 003 101	−116.5	2344	−21.4	2376
Starting age (mean of distribution)
30 years	306.7	194.6	211.9	1 978 959	1 979 806	1 978 953	−112.0	848	−17.3	854
40 years	370.5	257.2	278.0	1 933 075	1 934 407	1 933 072	−113.3	1332	−20.8	1335
60 years	674.1	581.0	596.8	1 603 495	1 605 381	1 603 524	−93.1	1886	−15.8	1857
Discounting†
Costs 3%, QALYs 0%	493.5	386.4	406.1	2 633 348	2 636 361	2 633 329	−107.1	3013	−19.7	3031
Costs 0%, QALYs 0%	786.6	631.0	659.9	2 633 348	2 636 361	2 633 329	−155.7	3013	−28.9	3031

*Analyses were performed by changing the parameter of interest and rerunning the model with 5000 Monte Carlo simulation.

†In general, people value instant benefits, for example, a golden tan versus avoiding skin cancers in future. This time preference for seeking benefits now rather than later is dealt with through discounting, giving future benefits a lower present value than immediate benefits. However, this makes prevention initiatives more unfavourable than without discounting. In prevention analyses therefore, discounting is controversial and warrants scenario analyses.

QALYs, quality-adjusted life years.