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

TABLE 82 Drug costs used in the cost–utility model submitted by Eli Lilly
then used to calculate the probability that an
adverse event experienced by a patient on IR-
MPH was insomnia, and this was estimated to be
46%. It is likely that the proportion of adverse
events that are insomnia would be available
directly from clinical trials of IR-MPH, and so the
need for this indirect calculation is not clear.
Adverse events other than insomnia are given a
47.3% chance of persisting to the next cycle for
the first four cycles in the model and a 100%
chance of persisting thereafter. Insomnia is given a
95.3% chance of persisting to the next cycle for
the first four cycles in the model and a 100%
chance thereafter. These estimates are a modelling
assumption made with consideration of expert
opinion.
Summary of resource utilisation and
cost data
The model includes only the costs of the active
medication and excludes all other costs. The
estimated daily dose of each medication was taken
from published sources (IMS BPI/HPAI database
2003, reference not provided in submission). The
source of the unit costs of each medicine is
unclear. As ATX is flat-priced regardless of dose,
the submission assumes that 90% of patients will
take one tablet per day and 10% will take two. The
drug costs used in the model are shown in
Table 82.
Health Technology Assessment 2006; Vol. 10: No. 23
Value ATX IR-MPH ER-MPH DEX
Average daily dose 1.1 pills 25.46 mg 32.75 mg 13.11 mg
Daily cost (£) 2.15 0.47 1.34 0.18
Monthly cost (£) 64.35 14.19 40.04 5.40
TABLE 83 Utility values used in the cost–utility model submitted by Eli Lilly
Health state N Mean SD
Treatment with ATX; responder; no side-effects 83 0.959 0.077
Treatment with ATX; responder; side-effects 83 0.937 0.096
Treatment with ATX; non-responder; no side-effects 83 0.902 0.133
Treatment with ATX; non-responder; side-effects 83 0.886 0.148
Treatment with IR-MPH; responder; no side-effects 83 0.913 0.128
Treatment with IR-MPH; responder; side-effects 83 0.904 0.137
Treatment with IR-MPH; non-responder; no side-effects 83 0.889 0.154
Treatment with IR-MPH; non-responder; side-effects 83 0.875 0.164
Treatment with ER-MPH; responder; no side-effects 83 0.930 0.107
Treatment with ER-MPH; responder; side-effects 83 0.912 0.124
Treatment with ER-MPH; non-responder; no side-effects 83 0.898 0.130
Treatment with ER-MPH; non-responder; side-effects 83 0.884 0.143
No medication; responder 23 0.880 0.133
No medication; non-responder 23 0.880 0.133
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Summary of utility data
The utility data were based on a study previously
published as a poster. 145 This study obtained
utility values for 14 hypothetical health states from
83 parents as proxies for their children with
ADHD using SG. The 18 health states were
differentiated according to treatment received,
response and side-effects, and the vignettes
describing each state were designed to maximise
the differences between the treatment options.
The results of this utility study are shown in
Table 83.
DEX was not included in the utility study, and so
the model assumes that the values for treatment
with IR-MPH are applicable. Some of these utility
values appear inconsistent, for example, the utility
for a non-responder to ATX who is experiencing
side effects with treatment is higher than that of a
person receiving no medication. The health state
descriptions shown to parents in the elicitation
study are shown in Appendix 10. The main
difference between ATX and the stimulant
therapies is related to treatment coverage in the
early morning and late evening. This translates
into a difference in utility of approximately 0.04
between responders to ATX and IR-MPH. This is
a relatively large difference in utility in this
population. As the results of this study are only
available in poster format, it is not possible to
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