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

did not include a ‘global’ HRQoL measure for use
as the primary outcome measure in an economic
evaluation.
The CCOHTA analysis by Zupancic and
colleagues 126 undertook a cost-effectiveness
analysis using a decision analytic model to compare
six interventions including the pharmacological
intervention magnesium pemoline (PEM). The
base case analysis was conducted excluding PEM
and this is of most relevance in the UK where PEM
is no longer prescribed owing to an increased risk
of liver failure. Therefore, five interventions were
compared including two pharmacological
strategies: IR-MPH and DEX, one
psychological/BT and one combination of
psychological/BT and IR-MPH for ADHD in
children and adolescents. The interventions were
compared with a no treatment alternative. The
analysis was conducted from the Canadian, thirdparty
payer perspective and, like the Gilmore and
Milne study 123 a 1-year time horizon was adopted.
The effectiveness measure used in the economic
evaluation was the Abbreviated CTRS and
estimates were derived from the meta-analysis of
published clinical trials. The model determined
cost in relation to a one- and a six-point reduction
in mean CTRS. A six-point reduction in CTRS was
considered as a valid and reliable indicator of a
clinical response to treatments for ADHD, 54
corresponding to approximately one SD in the
distribution of the CTRS in the studies analysed.
The CTRS is widely used in trials and contains
core and associated features of children with
ADHD that the authors believed to be important.
The CTRS contains 10 items that have been found
to be sensitive indicators of medication effects.
Five items relate to core ADHD symptoms of
inattention/distractibility, hyperactivity and
impulsivity and five to commonly associated
characteristics including social and academic
adjustment problems that these children
TABLE 65 Expected costs and effects of alternative strategies, excluding PEM
© Queen’s Printer and Controller of HMSO 2006. All rights reserved.
Health Technology Assessment 2006; Vol. 10: No. 23
experience (disruptive behaviour, inconsistency,
low frustration tolerance, emotional lability). Two
key assumptions are implicit in using the CTRS as
a continuous rating scale, that is, that the cost and
desirability of achieving a small gain in CTRS
score for many children are assumed to be the
same as those of achieving a large gain in CTRS
score for few children and that efficacy is constant
across baseline levels of ADHD severity. However,
the efficacy of stimulants may depend on the
quality and severity of symptoms. An attrition rate
of 35% was modelled over 6 months based on a
previous study (Miller and colleagues, unpublished
work) and at 1 year this was estimated to be 15%.
The costs of care included all interventions
(including drugs and/or BT contacts), doctor visits
and hospitalisations. Resource use was based on
evidence in the literature and three expert panels.
Unit cost data were obtained from the literature
and were expressed in 1997 Canadian dollars.
Typically in Canada, the costs for psychological
therapies accrue to families except where the
service is obtained from the public sector; however,
for the sake of consistency, it was assumed these
costs were borne by the Ministry. Children on IR-
MPH were assumed to have four doctor visits and
two specialist visits per year and two laboratory
tests at baseline and at 1 year. Children on DEX
were assumed to have three doctor visits and two
specialist visits. BT included 16 hours of
counselling, 8 hours of parent training and 2 hours
of teacher training. Combined therapy combined
the resource use of BT and IR-MPH above.
Children on no treatment were assumed to receive
an additional four doctor visits compared with their
unaffected peers. It was assumed that the children
remained on drug treatment for 1 year and that
any adverse drug reactions, beneficial effects and
costs ceased with discontinuation of the therapy.
Analysis of expected costs and outcomes of
different options indicated that IR-MPH was the
Strategy Cost (Can$) Incremental Effectiveness Incremental Incremental
cost (Can$) (CTRS points) effectiveness cost-
(CTRS points) effectiveness
Do nothing 128 0
IR-MPH 559 431 6.7 6.7 64
DEX 566 7 4.7 –2.0 D
BT 1946 1380 0.3 –4.4 D
BT/IR-MPH combination 2505 559 3.8 3.5 D
D, dominated.
83