Memorandum by Alec Miners, Brunel University
This is an "edited" and "updated"
version of the discussion that accompanied an economic evaluation
comparing treatment with highly active antiretroviral therapy
with two nucleoside analogues (NA) .
Since 1997, the mainstay of antiretroviral therapy
for individuals in the UK infected with the human immunodeficiency
virus (HIV) has been treatment with highly active antiretroviral
therapy (HAART) which includes the addition of at least one protease
inhibitor (PI), a non-nucleoside reverse transcriptase inhibitor
(NNRTI) or a third nucleoside analogue (NA) in combination with
two NAs. This is based on evidence that HAART is more efficacious
in reducing disease progression and mortality compared with two
NAs alone [2-6]. However, ever increasing pressures on health
care budgets has made it important for health care technologies
not only to demonstrate their safety and efficacy but also to
show that they are cost-effective.
In this economic evaluation of HAART, cost-effectiveness
was assessed using modelling techniques to combine information
on treatment costs and disease progression for adults from observational
data from English treatment centres. Assuming that the clinical
effect of HAART lasts for five years, produced ICERs of £14,602
per life-year saved and £17,698 per QALY saved. Moreover,
although the sensitivity analysis showed that the baseline ICER
was particularly sensitive to variables such as the discount rate,
by assuming continuous costs of HAART for the whole 20-year period
despite but on average five-year treatment effects, a conservative
estimate of the cost-effectiveness of HAART was produced. Using
the Wessex Institute of Public Health Decision Matrix  which
takes into account the size of the ICER and the quality of the
information used in its construction to interpret these results,
the use of HAART for adults compared with dual NA therapy is "recommended"
on economic grounds.
The ICER of £14,602 per life-year saved
is higher than the ICERs produced by Cook et al.  of
US$13,229 (approximately £8,500) per life-year saved and
Reisbrough et al.  CAN$13,900 (approximately £8,200).
Apart from the fact that these studies are set in different health
care systems, in our study the costs of HAART were assumed to
be continuous and independent of clinical effect. The study by
Risebrough et al. also included estimates of the costs
of salvage therapy and the indirect costs associated with HIV
infection. If indirect costs were included in our analysis, cost-effectiveness
is likely to increase because many individuals infected with HIV
are likely to be of working age and treatment may help to reduce
these indirect costs. Sendi et al.  estimated the incremental
cost-effectiveness of HAART with at least one PI from a Swiss
health services perspective to be 33,000 CHF (approximately £10,000)
per life-year saved. However, for this Swiss study, the comparative
treatment programme was "no treatment" which is unrealistic
in an English setting. A more recent US economic evaluation by
Freedberg et al.  reported the cost-effectiveness of HAART
to be US$23,000 (approximately £15,000) per QALY gained.
However, this study also compared the use of HAART with "no
In conclusion, the results from this analysis
suggest that HAART is, at the very least, a moderately cost-effective
method of treating individuals infected with HIV compared with
two NAs alone. However, reductions in the cost of HAART would
dramatically increase cost-effectiveness and longer-term data
on the relative effectiveness of HAART are required to fully substantiate
these findings. Finally, whether treatment with an NNRTI as a
third drug is more cost-effective than treatment with a PI and
when treatment should be started, remains to be determined.
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