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

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Economic model
TABLE 101 Response rates defined as score of ≤ 1 on the SNAP-IV scale
Trial Treatment Responders (%) No. in group
Steele, 2004 ER-MPH12
IR-MPH
[Confidential information removed]
Swanson, 2001 a
IR-MPH 81 (56) 144
IR-MPH + BT 99 (68) 145
Community comparison 37 (25) 146
a Results for BT alone omitted as not relevant to this review.
TABLE 102 Response rates estimated in extended MTC model in WinBUGS: response defined on CGI-I, CGI-S, ADHD-RS or SNAP-IV
Treatment Response rate, CGI-I baseline (SD) Response rate, ADHD-RS baseline (SD)
Placebo 0.29 (0.07) 0.39 (0.10)
IR-MPH 0.64 (0.12) 0.74 (0.11)
ER-MPH8 0.59 (0.14) 0.69 (0.13)
ER-MPH12 0.79 (0.10) 0.85 (0.09)
ATX 0.60 (0.11) 0.70 (0.11)
DEX 0.89 (0.10) 0.93 (0.07)
The ADHD-RS is chosen as the baseline response
rate, in order to obtain parent-rated estimates of
treatment effect. The results of this analysis are
compared to the same model using a CGI-I
baseline, to aid comparison with the base case
results. These data are shown in Table 102.
Again, the new information has altered the
response rates somewhat, but the order in terms of
treatment effect remains the same. Response
defined on the ADHD-RS produces a higher
absolute number of responders than response
defined on the CGI-I scale.
Results using all clinician-rated response
Table 103 shows the results of the model using the
response rates reported in Table 98. The new sets
of response rates alter the results slightly because
strategy 13 no longer dominates all the other
strategies. Instead, strategy 15 (first-line DEX,
second-line ER-MPH12, third-line ATX) is more
effective, but at a higher cost. The point estimate
of response to ER-MPH12 is higher than the point
estimate of response to IR-MPH in the base case
and in the extended MTC, but in the latter model
the relative difference in treatment effects is more
favourable towards ER-MPH12.
The cost per QALY gained with strategy 15
compared with strategy 13 falls when responses
are estimated on the CGI-S scale in comparison to
the CGI-I scale. This is because overall the
response rates are lowered when measured on
CGI-S, and there is greater potential to increase
the number of responders by switching to a more
effective treatment. In the analysis using response
measured on CGI-I, a much larger proportion of
patients will have responded to first-line DEX, so
the potential for increasing the number of
responders by altering the second- or third-line
therapies is reduced. In both cases, the cost per
QALY gained with strategy 15 compared with
strategy 13 is probably outside the range of values
normally considered to be cost-effective, so
strategy 13 remains optimal.
For both of these analyses, if DEX is not
considered suitable as first-line therapy, the
optimal strategy is number 7 (first-line IR-MPH,
second-line DEX, third-line ATX). Strategy 9 is
not ruled out by dominance or extended
dominance, but the cost per QALY gained
compared with strategy 7 is outside the range
normally considered cost-effective (>£150,000 per
QALY).
Results using parent-rated response: synthesising
all response rates
Table 104 shows the results of the model using the
response rates reported in Table 102. The results
are very similar to those using only clinician-rated
response data (Table 101). Strategy 13 is no longer
the dominant treatment strategy, but the cost per
QALY gained to move to the next most effective
strategy, number 15, is outside the range normally
considered cost-effective.