Hyperbaric Oxygen Therapy - Hyperbaric Chamber Information ...

Pooled results
Given the lack of clinical, epidemiologic and statistical heterogeneity across the identified
studies the review proceeded to examine statistically pooled estimates of treatment effect
for each of the outcomes with sufficient data to allow this, namely major amputation,
minor amputation and wound healing. Each treatment effect was examined from the
perspective of both relative and absolute risk.
Risk of major amputation
Major amputation was defined as amputation above the ankle joint. The review examined
outcomes for 251 subjects.
Study
-.75 -.5 -.25 0 .25 .5
Risk difference
Risk difference
(95% CI)
.01 .1 1 10
Odds ratio
Figure 3. Individual study and pooled results for the relative
risk of major amputation following exposure to
HBOT compared to comparison therapy.
28 Hyperbaric oxygen therapy
Study
Odds ratio
(95% CI)
% Weight
Baroni (1987) 0.19 (0.03,1.30) 12.2
Doctor (1992) 0.18 (0.03,1.07) 14.1
Faglia (1996) 0.19 (0.05,0.75) 23.8
Faglia (1998) 0.35 (0.13,0.91) 50.0
Zamboni (1997) (Excluded)
0.0
Overall (95% CI)
% Weight
Baroni (1987) -0.29 (-0.63,0.05) 8.4
Doctor (1992) -0.33 (-0.64,-0.03) 10.2
Faglia (1996) -0.25 (-0.43,-0.06) 27.7
Zamboni (1997) 0.00 (-0.31,0.31) 9.8
Faglia (1998) -0.18 (-0.32,-0.03) 43.8
Overall (95% CI)
The relative risk for major
amputation was reduced in all studies,
but only reached statistical
significance in those conducted by
Faglia et al. 47,48 The pooled result
shows there was a reduction in risk
(odds ratio (OR) = 0.25; 95%
Confidence Interval (CI) = 0.13, 0.50;
p < 0.0001) in those patients
undergoing HBOT compared to
those undergoing comparison
therapies (Figure 3). Subjects exposed
to HBO were 75 percent less likely to
experience major amputations
compared to those subjects given the
comparison therapies. The study by
Zamboni et al. 50 was excluded from this
pooled estimate of effect because they
reported no major amputations.
-0.20 (-0.30,-0.11)
Figure 4. Individual study and pooled results for the
absolute risk reduction of major amputation
following exposure to HBOT compared to
comparison therapy.
0.25 (0.13,0.50)
Figure 4 shows the absolute reduction in risk of major amputation for each of the five
studies and for the pooled result. Except for Zamboni et al, 50 all other studies reported a
decrease in the risk difference
associated with HBOT with the
studies by Faglia et al and Doctor et al
reaching statistical significance. 47-49
The pooled risk difference indicates
that a reduction of 20 percent (95%
CI = 11, 30%; p < 0.0001) in the
number of major amputations is
experienced by subjects following
exposure to HBOT. One major
amputation is prevented for every 5
subjects exposed to HBOT (95% CI
= 3.3, 9.1).