Hyperbaric Oxygen Therapy - Hyperbaric Chamber Information ...

Figure 7 shows the absolute difference in the risk of minor amputations for each of the
three studies and for the pooled result. Except for the study by Zamboni et al, 50 all other
studies reported an increase in the absolute risk difference associated with HBOT. The
pooled risk difference indicates that an increase of 9 percent (95% CI = -8, 25%; p =
.295) in the number of minor amputations is experienced by subjects following exposure
to HBOT. For every 11 patients exposed to HBOT, one more will experience a minor
amputation than in a comparable group provided comparison therapy.
Risk difference
Study (95% CI) % Weight
Doctor (1992) 0.13 (-0.15,0.42) 33.9
Faglia (1996) 0.11 (-0.15,0.38) 38.4
Zamboni (1997) 0.00 (-0.31,0.31) 27.6
Overall (95% CI)
-.5 0 .5
Risk difference
0.09 (-0.08,0.25)
Figure 7. Individual study and pooled results for the
absolute risk of minor amputation following
exposure to HBOT compared to comparison
therapy.
Given the small number of studies, no sensitivity analyses were performed.
Although the identified studies demonstrated that HBOT reduced major amputations,
the treatment effect on minor amputations was in the opposite direction. That is, the
trend of both the relative and absolute risk of minor amputation was higher in the
HBOT group, although neither risk reached commonly accepted levels of statistical
significance. A possible explanation is that HBOT subjects preserved their limbs from
major amputation because of the efficacy of the intervention, thus making them as a
group more liable to minor amputation. If this explanation is valid the increased risk of
minor amputation in the HBOT subjects could conceivably be interpreted as a positive
outcome. Unfortunately the review could not examine this hypothesis further, since
major amputation and minor amputation were not mutually exclusive outcomes.
30 Hyperbaric oxygen therapy