Results of the base case analysis

Costs and benefits expected to arise to the population of eligible treatments under different possible outcomes in the ‘with research’ state can be calculated by multiplying the costs and QALYs under each outcome by each treatment’s hypothesised prescription share. Here, the likelihood of observing a possible outcome is the same across these outcomes; in other

words, no likelihood weights are attached to indicate that any of these outcomes is more likely to occur. Results of this non-weighted analysis are given in Table 6.4.

Table 6.4: Non-weighted costs and benefits of research in base case analysis (NSCLC)

Favourable outcome Inconclusive outcome Unfavourable outcome With research

Cost £90,081,664 £86,511,060 £82,960,067

Trial cost £336,721 £336,721 £336,721

QALYs 8617 8241 7985

Without research

Cost £86,868,565 £86,511,060 £85,477,767

QALYs 8425 8241 7931

Net implications

Net cost £3,549,820 £336,721 -£2,180,979

Net QALYs 192 0 55

Cost per QALY £18,450 per additional QALY

Costs for no additional QALYs

Cost savings for additional QALYs

NMBwith research £168,103,680 £160,370,345 £156,267,944

NMBwithout research £165,881,317 £160,707,066 £152,446,181

INMBs (£30,000 per QALY) £2,222,363 -£336,721 £3,821,763

With research and under a specific outcome, the cost (or QALYs) are found by multiplying the discounted eligible population by the sum resulting from the combination of costs (or QALYs) associated with the outcome and the hypothesised uptake in clinical practice. For example, under a ‘favourable’ outcome, the cost and QALYs ‘with research’ ( ) are found as:

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(

)

(

)

Under the same outcome, in the absence of research ( ), clinical practice is assumed to remain as it is, with half of the patients taking Gem+Carb and the rest taking Gem+Cisp. In this situation, the costs and QALYs are estimated as follows:

(

)

(

)

In this way, the costs and QALYs with and without further research (here, the proposed BTOG-2 trial) can be estimated for each of the three possible outcomes. On the basis of these costs and QALYs, the ICER and INMBs for the ‘favourable’ outcome are shown below:

and

The cost per QALY and the INMBs associated with each possible outcome have been calculated in the same way.

Under the ‘favourable’ outcome for Gem+Carb, carrying out the BTOG-2 trial is estimated to result in greater costs and more QALYs than in a situation without the trial (Table 6.4). This is because under this outcome more patients will be offered Gem+Carb, which, in this case, is assumed to be more costly and more effective than Gem+Cisp. As obtaining an additional QALY in this case is expected to cost less than the ceiling ratio of £30,000, conducting

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research is expected to result in positive INMBs of about £2.22 million (ICER of £18,450 per QALY). Given an ‘inconclusive’ outcome, conducting the trial would result in no additional QALYs (as no change in prescription is expected to take place) for an extra cost equal to the cost of the trial. As a result, this outcome is associated with negative INMBs of £336,700.

Last, under the ‘unfavourable’ outcome, conducting the trial is associated with an increase in QALYs and cost savings. This is because, under the specific outcome, clinical practice will move towards restricting the use of the more costly and less effective Gem+Carb. In this situation, carrying out research appears particularly appealing, leading to additional NMBs of approximately £3.82 million.

To reflect the fact that different outcomes are associated with different likelihoods of occurrence, each possible outcome was assigned a likelihood weight and formed different combinations. In line with methods used in previous applications of the PATHS model^67;116, three combinations were formed:

a. ‘Optimistic’, where the probability of observing a ‘favourable’, ‘inconclusive’ and

‘unfavourable’ outcome is 0.5, 0.25 and 0.25, respectively;

b. ‘Neutral’, where each outcome has an one-third probability of being observed, and

c. ‘Pessimistic’, where the probability of observing a ‘favourable’, ‘inconclusive’ and

‘unfavourable’ outcome is 0.25, 0.25 and 0.5, respectively.

The weighted net costs, net QALYs and INMBs for each of these combinations are given in Table 6.5, Table 6.6 and Table 6.7. In each of these tables—and in all tables of the same form throughout this chapter—the second column gives the attached likelihood weight, while the third and fourth columns give the weighted costs and QALYs, respectively. For each possible outcome, the weighted cost (or, equivalently, the weighted QALYs) is calculated by multiplying the relevant net cost (net QALYs) as found in the non-weighted analysis (Table 6.4) by the respective likelihood weight (e.g. weighted cost of ‘favourable’

outcome in ‘optimistic’ combination = 3,549,820 0.5 = 1,774,910).

The last column in each table gives the weighted INMBs calculated as weighted QALYs multiplied by the ceiling ratio, minus weighted costs (e.g. weighted INMBs of ‘favourable’

outcome in ‘optimistic’ combination = 96 £30,000 £1,774,910 = £1,111,181. Last, the total weighted INMBs for a specific combination are calculated as the sum of the weighted INMBs of each outcome and are given in the bottom-right cell of each table. According to the results, carrying out the proposed BTOG-2 trial is estimated to lead to positive INMBs of

£1.98 million, £1.88 million and £2.38 million under the ‘optimistic’, ‘neutral’ and

‘pessimistic’ combinations, respectively.

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Table 6.5: Weighted costs and benefits of research in base case analysis (‘optimistic’ combination) (NSCLC)

Optimistic combination

Weighted ICER and INMBs £11,958 per additional QALY £1,982,442

Table 6.6: Weighted costs and benefits of research in base case analysis (‘neutral’ combination) (NSCLC)

Neutral combination

Unfavourable 0.33 -£719,723 18 £1,261,182

Sum of weighted net costs

and QALYs - £562,836 82 -

Weighted ICER and INMBs £6,902 per additional QALY £1,883,444

Table 6.7: Weighted costs and benefits of research in base case analysis (‘optimistic’ combination) (NSCLC)

Pessimistic combination

Unfavourable 0.50 -£1,090,489 27 £1,910,882

Sum of weighted net costs

and QALYs - -£118,854 75 -

Weighted ICER and INMBs Cost savings of £118,854 and 75

additional QALYs £2,382,292

In summary, the results of this analysis suggest that conducting the trial and changing clinical practice according to its results would result in additional health benefits at a value lower than society (or a decision-maker) is assumed to be willing to pay for these benefits, resulting in positive NMBs. In this respect, according to the interpretation used in ‘payback’

studies^67;116, the BTOG-2 trial represents a ‘cost-effective’ use of resources.