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

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Review of economic evaluations of ADHD drug interventions in children and adolescents
TABLE 76 Unit costs of IR-MPH, Equasym XL and DEX used in the cost–utility model submitted by Celltech
Drug Pack Price (£)
DEX 5 mg × 28 2.61
IR-MPH 5 mg × 30 2.78
10 mg × 30 5.57
20 mg × 30 9.98
Equasym XL 10 mg × 30 25.00
20 mg × 30 30.00
30 mg × 30 35.00
according to a published UK protocol. 140 It was
assumed that 50% of the titration period would be
at an average dose of 5 mg and 50% at an average
of 10 mg once daily. Non-compliers were assumed
to incur the same drug costs as those complying
with therapy.
The resource use associated with ADHD was based
on Wessex DEC evaluation, 123 which used expert
opinion to determine treatment patterns. All
patients receiving drugs were assumed to receive
six outpatient visits with a child psychiatrist or
paediatrician at a cost of £111 per visit, and six
GP visits per year at a cost of £20. 141 Patients
discontinuing treatment were assumed to receive
two outpatient visits per year. Patients receiving
BT were assumed to receive eight 100-minute
consultations, 50% with members of a
child/adolescent psychiatry team and 50% with
members of a clinical psychology team. The cost
of these was obtained from published UK
sources, 141 and was £64 per person-hour for the
psychiatry team and £39 per hour for the
psychology team. Non-compliers were again
assumed to receive the same cost as compliers.
The model did not include any costs associated
with side-effects of treatment.
Summary of utility data
The base case analysis used utility values from a
previously published evaluation of treatments for
ADHD. 4 These were calculated using EQ-5D, by
assuming that an untreated ADHD patient
corresponded to the EQ-5D health state 11211,
which gives a utility of 0.883. A successfully treated
patient was assumed to return to full health,
health state 11111, giving a utility of 1.000.
Summary of cost-effectiveness
The base case analysis compared Equasym XL
with no treatment in patients unable to comply
with twice-daily IR-MPH. The estimated total costs
and QALYs for no treatment were £0 and 0.883
(no probabilistic parameters were involved in this
calculation). The total costs and QALYs for
Equasym XL were estimated to be £1073 (95% CI
£1035 to 1116) and 0.9562 (95% CI 0.9425 to
0.9667). The ICER for Equasym XL compared
with no treatment was therefore estimated to be
£14,657 per QALY (95% CI £12,564 to 18,538).
The 95% CI for the ICER was calculated by taking
the 5th and 95th percentile of the 10,000
probabilistic simulations. In this instance this
method is valid because all of the simulated
incremental costs and benefits of Equasym XL lay
in the northeast quadrant of the cost-effectiveness
plane (i.e. Equasym XL was more effective and
more expensive than no treatment in all
simulations), and so the problem of negative
ICERs did not arise. The probabilistic simulations
were used to plot a CEAC, which showed that at a
willingness-to-pay threshold of £30,000 per QALY,
Equasym XL was the most cost-effective strategy in
100% of simulations.
A number of one-way sensitivity analyses were also
conducted in which the ICER for Equasym XL
compared with no treatment was shown to remain
under £30,000 per QALY for a range of values
input for compliance to the morning dose of
medication, the utility estimates, response rate,
length of titration, cost of paediatric outpatient
appointments and drug costs for non-compliant
patients. The results of these are shown in Table 77.
A second scenario considered three times daily
dosing, where the dose of Equasym XL must be
supplemented with an evening dose of IR-MPH.
This increased the costs of Equasym XL to £1.45
per day. Compliance to this evening dose of IR-
MPH was assumed to be 85%. The reported result
from this analysis is an ICER of £15,536 for
Equasym XL relative to no treatment.
The secondary analysis compared Equasym XL
with IR-MPH and no treatment. The estimated
costs and QALYs for the no treatment and