A systematic review and economic model of the effectiveness and ...

TABLE 77 Results of sensitivity analyses conducted in the cost–utility model submitted by Celltech
Equasym XL arms remained the same as in the
base case analysis. The estimated total costs and
QALYs for IR-MPH were £930 and 0.9433. When
more than two programmes are being compared,
the ICERs are calculated using the following
process:
1. The strategies are ranked in terms of cost (from
the least expensive to the most costly).
2. If a strategy is more expensive and less effective
than the previous strategy, then this strategy is
said to be dominated and is excluded from the
calculation of the ICERs.
3. The ICERs are calculated for each successive
alternative, from the cheapest to the most
costly. If the ICER for a given strategy is higher
than that of the next more effective strategy,
then this strategy is ruled out on the basis of
extended dominance.
Finally, the ICERs are recalculated excluding any
strategies that are ruled out using the notions of
dominance and extended dominance. The ICER
for IR-MPH compared with no treatment was
£15,432 per QALY and the ICER for Equasym XL
compared with IR-MPH was £11,043 per QALY.
Hence in the secondary analysis, IR-MPH was
extended dominated by Equasym XL. The results
of the secondary analysis were very sensitive to the
choice of compliance rates, and the results of a
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Health Technology Assessment 2006; Vol. 10: No. 23
Parameter value ICER for Equasym vs no treatment (£)
Compliance to morning dose (£)
50 26,748
100
Utility (treated, non-treated)
12,066
1.000, 0.692 5,568
0.970, 0.884
Daily cost Equasym XL (baseline £1.17) (£)
15,238
0.58 12,827
1.76
Response rate (%)
16,487
60 14,836
82
Length of titration period (days)
14,237
21 13,634
70
Cost of outpatient appointment (£)
16,256
89 12,991
138 16,702
Reduction in drug cost for non-compliant (%)
50 14,383
100 14,108
two-way sensitivity analysis of these are shown in
Table 78.
Although the submission does not clarify whether
the negative ICERs are the result of a positive
difference in cost and a negative difference in
effect, or of a negative difference in cost and a
positive difference in effect, one can assume that
they were a result of the former as they fall into
those analyses where the compliance to the
lunchtime dose is higher than compliance to the
morning dose.
Introducing costs for the in-school administration
of a lunchtime dose into this secondary analysis
improved (reduced) the ICER for Equasym XL
compared with IR-MPH.
Comments on methodology
Choice of comparators
The model did not include the full range of
comparators. This was justified in the model by
specifying the potential population to be those
patients who were intended to receive IR-MPH
twice daily, and so longer-acting alternatives such
as Concerta XL and ATX would not be relevant. A
secondary analysis that considered patients
requiring IR-MPH three times daily also did not
then introduce those further relevant comparators
such as Concerta XL and ATX.
95