Hyperbare Zuurstoftherapie: Rapid Assessment - KCE

48 Hyperbaric Oxygenation Therapy KCE Reports 74
4.3.1.6 Comments
The first study of Abidia et al. 80 showed there was an improvement in ulcers healed at
one year and a potential cost saving with the use of HBOT. On the other hand, there
was no improvement in QoL or amputation rates. The authors acknowledged that one
of the limitations of their study was that only the cost of dressing changes and HBOT
were included. Furthermore, the authors also state that the results must be viewed
with caution and viewed as preliminary because of the small sample size.
Guo et al 81 also mentioned some limitations of their study. One of the assumptions was
that foot ulcers would not recur once they were healed. If foot ulcers would recur, this
would increase cost-effectiveness ratios. In contrast, taking into account the improved
speed of wound healing and reduction of the level of wound care utilization would
decrease the ICER. With respect to costs, the costs of treating side effects were
excluded because they were assumed to occur rarely. Finally, the authors mentioned
the cost-effectiveness estimation was based on studies that had methodological
weaknesses. 111 The probabilities of treatment outcomes were based on four
prospective, controlled, clinical studies in which different number of treatments and
treatment schemes of HBOT was given. Furthermore, two of these studies 98, 99 were
randomized but not blinded and the other two 100, 101 were both not randomized.
Similar as in the previous study, Hailey et al 79 also assumed that LEAs occur in the first
year. If patients were healed in the first year, they would not have a subsequent LEA.
Patients who were unhealed in the first year would remain so for the remainder of their
lifetime and would receive wound care intermittently. We are aware that no more
detailed data were available; however, this remains a very strong assumption. Hailey et
al. also admit that both cost and effectiveness estimates are not of high quality. With
respect to effectiveness, they point at the fact that there are few comparative studies of
HBOT, and all of them have limitations. Costs, which were based on data from a few
centres without standardized reporting, were assessed of not being of high quality.
Even though the result was dominant, and sensitivity analyses showed results to be
robust, Hailey and colleagues admit there was uncertainty regarding the costeffectiveness
of using HBOT versus standard care.
In the Australian study, 69 the same caveats are mentioned. Costs are rough estimates.
The estimates of HBOT treatment costs are not precise estimates based on actual
studies, but are based on estimates of staffing and capital costs of a hyperbaric
monoplace unit obtained from expert opinion. The cost for major amputations was the
average cost for all types of amputations. First of all, this may not be an appropriate
estimate for patients with diabetes. Secondly, the authors also remark that no
information on the incremental resource use is available. Calculating the full costs for
amputation as a saving due to HBOT may overestimate cost savings since costs may
already have been incurred for diabetic wounds. Costs for rehabilitation and minor
amputation may also not be accurate but were used in the absence of more precise
data. There also remained considerable uncertainty surrounding the clinical evidence of
the effectiveness, especially the assumed risk of minor amputations and wound healing
being based on small populations. The authors stated that their appraisal represents
only an indication of the potential cost effectiveness of monoplace HBOT, rather than a
complete and detailed estimate of the cost effectiveness of the technology.
Finally, the study of Wheen et al. 83 contains similar weaknesses as the other studies. On
the one hand, more cost items are included in this study, such as prosthesis supply and
training, occupational therapy and physiotherapy input, and costs for a walking frame
and crutches. On the other hand, the main cost difference between HBOT and standard
therapy was caused by differential pricing for hospital stay for HBOT (NZ$120) versus
standard therapy (NZ$450). The latter results in misleading base case results. For
effectiveness, the input parameters were based on one of the most optimistic studies.
In conclusion, all the economic evaluations have their weaknesses, both on cost and
effectiveness side. This is in the first place due to a lack of qualitative input data.