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A Randomised Blinded Trial of Vaporisation versus
Excision of rASRM Stage 1-3 Endometriosis in Women with
Pelvic Pain.
P Barton-Smith (2010). An Investigation of the Surgical Treatment of
Endometriosis. MD Thesis. University of Surrey, UK.
Structured Abstract and Key Words
Objective
To determine whether excision or vaporisation is optimal for treating pelvic pain in
stage 1-3 endometriosis
Design
A randomised blinded trial
Setting
NHS District General Hospital
Patients
133 women with pelvic pain referred by their Family Practitioners for secondary care
between 2002-2008
Interventions
Excision with harmonic scalpel or vaporisation with CO2 laser at laparoscopy. Data
were collected pre-operatively and at 3, 6 & 12 months post-operatively.
Main outcome measures
The primary outcome measure was Endometriosis Health Profile (EHP-30) Core pain
domain. Secondary outcomes were VAS scores for dysmenorrhoea, dyspareunia,
chronic pelvic pain and dyschezia and EHP-30 HRQoL measures.
Results
Excision results in a significantly greater extent of improvement than vaporisation at
12 months (-23.9 vs -10.7 points/100, p=0.008). Women with deep disease did not
have a significant extent of improvement in pain following vaporisation (p=0.262).
The trial confirms previous studies that show that both excision and vaporisation
result in an equally significant proportion of patients showing some level of pain
improvement at 12 months (85.4 v 72.9%). Overall 20% of patients stay the same or
get worse.
Conclusions
Excision results in greater pain and quality of life improvement for stage 1-3 disease.
The range of improvement is wide and a proportion of patients continue to
deteriorate.
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Introduction
In the surgical treatment of endometriosis there are opposing views that favour either
vaporisation or excision as the optimal means of treatment. The “excisers” claim that
vaporisation is too superficial and does not go deep enough to remove infiltrating
tissue. The “vaporisers” claim their technique is faster and more efficient for the
removal of widespread disease and is just as effective. Two key randomised trials
have demonstrated that both vaporisation(1) and excision(2) of endometriosis results
in pain improvement for 62% and 80% of women, respectively. The limited evidence
regarding which is most effective is confined to a small randomised trial which reports
no difference in the proportion of women reporting pain improvement(3).
The aim of this trial was to show if there is a difference between the two techniques
in either the proportion of improvers or the extent of improvement in women
undergoing excision or complete vaporisation of endometriosis and fibrotic tissue
down to underlying normal tissue so that at the end of treatment the macroscopic
appearance is identical, not just a superficial treatment as often seen with ablation. In
the region of 82% of women have rASRM stages 1-3(4) so this trial covers the
majority of cases presenting to gynaecologists and excludes only severe disease.
Materials and Methods
The hypothesis was that there is no difference in pain improvement between excision
and vaporisation in the treatment of rASRM stage 1-3 endometriosis using the CO2
laser for vaporisation and harmonic scalpel for excision.
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Participants
Following ethical approval, all women meeting the eligibility criteria and scheduled for
surgery in a UK District General Hospital, were invited to take part in the study. The
inclusion criteria were, pelvic pain, visual diagnosis of stage 1-3 endometriosis, over
18 years of age, absence of contraindications to both treatments, and consenting to
participate. Women were excluded if pregnant, breastfeeding, unwilling to
discontinue hormonal treatment for six months post-operatively, or had other
conditions causing pelvic pain.
Randomisation
Participants were randomised in blocks of ten and group allocation was concealed in
sealed opaque envelopes. In theatre, if a visual diagnosis of endometriosis was
made, the rASRM score was calculated and where this was stage I-3, an envelope
was opened to determine group allocation. Patients and the post-operative assessor
were blinded to group allocation. Surgeons were blinded to the post-operative
outcomes.
Surgical procedures
All procedures were undertaken by three experienced laparoscopic surgeons.
Endometriosis was judged to be deep if on palpation it infiltrated >5mm below the
peritoneal surface. The rASRM score was reassessed for depth intra operatively as
lesions were treated. Vaporisation was performed by Sharplan CO2 laser at 300mm
focal length and 30w power with a 2.5mm Swiftlase spot using a Stortz 10mm
operating endoscope. Excision was by Ethicon Endo-Surgery LCS-C5 or ACE
Harmonic Scalpel.
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Outcomes
Data were collected by a researcher pre-operatively on the day of surgery, and at 3,
6, and 12 months post-operatively. The primary outcome measure was the
Endometriosis Health Profile-30 Core Pain domain(5). This provides a pain score
between 0-100 where 0 is the best possible state.
Pain was also assessed by 10 cm Visual Analogue Scales (VAS) for dysmenorrhoea,
dyspareunia, chronic pelvic pain, and dyschezia. Health-related quality of life
(HRQoL) was assessed by the Endometriosis Health Profile Questionnaire (EHP-30)
Core domains for control and powerlessness, emotional wellbeing, social support,
self-image, and sexual intercourse; each with a 0-100 score, where 0 is the best and
100 the worst possible outcome. Data on whether women took hormonal treatment,
had subsequent surgery or became pregnant in the year follow up period were also
collected.
Sample size
The sample size was based on the primary outcome measure EHP-30 Core pain
score. It has a recorded mean score change of 24.8/100 (SD 26) (6). In order to
detect an underlying difference of 20 points out of 100, 28 subjects are needed in
each treatment group (2-sided test with size = 5% and power = 80%). A further
power calculation was made for the VAS scores used in previous trials: The Food
and Drug Administration 80/20 rule for bioequivalence was used to calculate the
sample size required to achieve 80% power. Thus ε=0.20, ∝=0.2 (as equivalence
trial), 1-β=0.8. This needed to be a 2-sided test as it was possible the harmonic
scalpel was better than the laser. Assuming equivalence, then π1=π2=0.625. On this
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basis we required 53 patients in each arm if we were to have an 80% chance of
showing a 20% difference in VAS outcomes.
Data analysis
Group differences in the proportion of women reporting improvements in the primary
and secondary outcomes were tested using a Chi Square test. Differences in the
extent of improvement in each group were tested using unpaired t tests. Within group
differences at 12 months against baseline were tested using paired t tests. Pearson’s
Correlation was used to examine association between parametric continuous
variables and a Mann-Whitney U test was used to test for differences in ordinal data.
Following univariate analysis, a backward stepwise linear regression was used to
identify factors predictive of improvement. All statistical analysis was performed using
SPSS v17 (SPSS inc Chicago IL, USA; 2008).
Results
The table below shows that 66 women were randomised to receive excision and 67
to vaporisation. All were treated with the allocated intervention. All surgical
procedures were undertaken between November 2002 and May 2008.
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There were 22 pregnancies in 19 patients, 5 patients who underwent further surgery
and 16 patients who had hormonal therapy at some point during the 12month follow-
up period. All of these patients were included in the data analysis.
For the primary outcome measure the follow-up rates at 3, 6, and 12 months, taking
into account missing data and exclusions, were 122/133 (91.7%), 111/133 (83.5%)
and 96/133 (72.2%).
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Baseline Data
The mean age of patients was 32.9 years (SD 7.7; range 19-50). 87.9% patients
were equally distributed between rASRM Stages 1 and 2. The remaining 12.1% had
stage 3. Histology was taken in 65 of 133 cases (48.9%), 49 from the excision group
and 16 from the vaporisation group. Histology was not always possible from the
vaporisation group as biopsy may have resulted in excision. Overall 54/65 (83.1%)
cases had histology positive for endometriosis. Analysis of baseline variables in the
table below shows balanced groups except for a greater proportion of women in the
excision group with deep disease (p=0.009).
Characteristic Excision Vaporisation
(n=66) (n=66)______
Mean age +/- SD 33.05+/-6.69 32.74+/-8.65
Median rASRM score (IQ Range) 6(4-10) 6(3-9)
Positive Histology n/n (%) 41/49 (83.7) 13/17 (76.5%)
Deep disease n (%) 44 (66.7%) 28 (43.8%)
________________________________________________________________
Outcome Superficial Deep *p value
Mean +/-SD (n=66) (n=66)__________ ___________
EHP30 pain** 40.47+/-33.49 41.10 +/-22.28 p=0.899
Dysmenorrhoea *** 6.53 +/-2.69 6.65 +/- 2.71 p=0.809
Dyspareunia*** 4.15 +/-3.35 4.71 +/-3.20 p=0.36
CPP*** 4.77 +/-3.31 4.93 +/-3.17 p=0.785
Dyschezia*** 2.88 +/-3.44 3.29 +/-3.22 p=0.500
________________________________________________________________________
**EHP30 pain score out of 100
***VAS pain score out of 10
*unpaired t test
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Primary outcome measure: EHP30 Core Pain
In the whole study group 76 (80%) patients improved and 19 (20%) patients stayed
the same or were worse at 12 months. A similar proportion of patients reported
improvement in the EHP30 Pain score in the excision group (85.4%) and the
vaporisation group (72.9%).
Within group analysis in the table below revealed a significant improvement in
EHP30 Pain score at 12 months versus baseline for both the excision group (mean -
23.9 drop; p<0.0005), and the vaporisation group (mean -10.7 drop; p=0.001).
However at 12 months following surgery, women in the excision group reported
greater mean improvement in the EHP30 pain score (-23.9) compared with the
vaporisation group (-10.7) (p= 0.008; mean difference = -13.2; 95% CI -22.8 to -3.5)
Mean change 0 v 12 months +/- SD *p value (95%CI)_________
Excision -23.9 +/-26.2 p<0.0005 (-31.5 to -16.3)
Vaporisation -10.7 +/-20.8 p=0.001 (-16.7 to -4.7)
__________________________________________________________________________
*paired t test
Analysis point Excision Vaporisation Difference p value*
mean score improvement +/-SD mean (95%CI)____________
3 months -15.8 +/-21.1 -11.0 +/-15.8 -4.7(-11.5 to 2.0) 0.168
6 months -14.4 +/-23.3 -12.0 +/-17.9 -2.4(-10.3 to 5.5) 0.544
12 months -23.9 +/-26.2 -10.7 +/-20.8 -13.2 (-22.8 to -3.5) 0.008
__________________________________________________________________________
*unpaired t test
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Backward stepwise linear regression analysis also identified vaporisation as reducing
improvement in EHP-30 Core pain score at 12 months over baseline (r squared for
final model = 0.154, estimated loss of pain reduction = 12.24/100, 95%CI 2.81 to
21.67, p=0.012)
The overall results showing the comparatively better performance of excision versus
vaporisation for extent of improvement are shown in the following graph.
For the treatment of deep and superficial disease, excision resulted in statistically
significant improvement in pain score at 12 months versus baseline in both
superficial (mean -23.99 +/-26.36, p<0.001) and deep disease (mean -23.86 +/-
26.59, p<0.0005). However, vaporisation only showed statistically significant
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improvement for superficial disease (mean -17.89 +/-19.78, p<0.0005) and not for
deep (mean -4.44 +/-18.07, p=0.262). Comparatively, the table below shows no
difference in the extent of improvement between excision and vaporisation for
treating superficial disease (mean difference -6.10, p=0.402). However, improvement
in pain score for excision was significantly greater than achieved by vaporisation for
the treatment of deep disease (mean difference -19.42, p=0.005).
Disease Excision Vaporisation Difference p value*
mean score improvement +/-SD mean (95%CI) ____________
Deep -23.86+/-26.59 -4.44+/-18.07 -19.42(-32.61 to -6.23) 0.005
Superficial -23.99+/-26.36 -17.89 +/-19.78 -6.10(-20.67 to 8.46) 0.402
______________________________________________________________________
*unpaired t test
Analysis was carried out on the “per protocol” sub sample of women whose benefits
appear to be solely related to surgery; excluding those who became pregnant, took
hormonal medication or had subsequent surgery within the follow up period. There
were still 35 patients in each group at 12 months. Compared with vaporisation, the
excision group achieved a mean -11.62 point greater pain reduction in the EHP30
pain score (unpaired t test p=0.029 95%CI -22.02 to -1.23). Within this subgroup of
women, 14.6% of the excision group and 27.2% of the vaporisation group were either
the same or worse at 12 months (p=0.132)
VAS scores for Dysmenorrhoea, Dyspareunia, CPP and Dyschezia
The excision group reported statistically significant improvements in all four pain
modalities at 12 months. The vaporisation group reported 12-month improvements in
dysmenorrhoea (p=0.001) and dyspareunia (p=0.040), but not for CPP (p=0.060) and
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dyschezia (p=0.143). The proportion of women reporting improvement was similar in
both the excision and vaporisation group. The extent of improvement in CPP in the
excision group versus vaporisation was statistically significant at 6 (p=0.035) and 12
months (p=0.002) as seen below.
Analysis point Excision Vaporisation Difference p value*
mean score improvement +/-SD mean mean(95%CI)___________________
Dysmenorrhoea
3 months -1.26 +/-2.85 -1.33 +/-2.68 0.07(-1.02 to 1.15) 0.904
6 months -1.48 +/-2.80 -1.60 +/-3.01 0.12(-1.08 to 1.32) 0.841
12 months -2.94 +/-3.65 -1.50 +/-2.82 -1.44(-2.93 to 0.05) 0.059
CPP
3 months -1.64 +/-3.05 -1.31 +/-2.83 -0.33(-1.61 to 0.95) 0.612
6 months -2.38 +/-3.10 -0.99 +/-2.37 -1.38(-2.67 to -0.10) 0.035
12 months -3.50 +/-3.62 -0.93 +/-2.78 -2.57(-4.20 to -0.95) 0.002
Dyspareunia
3 months -2.42 +/-3.29 -1.97 +/-3.53 -0.45(-2.00 to 1.10) 0.564
6 months -1.91 +/-3.07 -2.36 +/-3.64 0.44(-1.17 to 2.05) 0.584
12 months -1.98 +/-3.34 -1.27 +/-3.42 -0.71(-2.49 to 1.07) 0.429
Dyschezia
3 months -1.58 +/-3.09 -2.32 +/-3.54 0.73(-0.96 to 2.43) 0.391
6 months -1.87 +/-2.99 -1.74 +/-3.10 -0.14(-1.78 to 1.50) 0.866
12 months -2.73 +/-4.18 -1.11 +/-3.42 -1.62(-3.97 to 0.72) 0.170
*unpaired t test
EHP-30 HRQoL outcomes
The excision group reported significant improvements in all of the EHP-30 HRQoL
domains at 12 months (p <0.001). The vaporisation group also reported significant
improvements in all of the EHP-30 HRQoL domains apart from self-image (0.194).
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Excision, however, resulted in significantly greater improvement than vaporisation at
12 months for all the EHP-30 HRQoL domains other than sexual intercourse
(p=0.855) as shown below.
Analysis point Excision Vaporisation Difference p value*
mean score improvement (+/-SD) mean(95%CI)_______
Control & powerlessness
3 months -22.73(+/-23.87) -11.94(+/-23.55) -10.80(-19.52 to -2.08) 0.016
6 months -18.75(+/-25.86) -11.48(+/-28.82) -7.27(-17.88 to 3.33) 0.177
12 months -30.56(+/-29.56) -12.86(+/-28.74) -17.69(-30.05 to -5.33) 0.006
Emotional wellbeing
3 months -16.53(+/-22.13) -9.04(+/-20.03) -7.49(-15.13 to 0.15) 0.055
6 months -17.19(+/-20.58) -10.11(+/-22.91) -7.08(-15.31 to 1.15) 0.091
12 months -24.74(+/-20.65) -13.95(+/-23.82) -10.80(-19.86 to -1.73) 0.020
Social support
3 months -16.41(+/-28.90) -2.55 (+/-24.75) -13.86(-24.40 to -3.32) 0.010
6 months -16.62 (+/-31.87) -2.17(+/-29.77) -14.45(-27.15 to -1.75) 0.026
12 months -31.25(+/-30.12) -12.35(+/-28.91) -18.90(-32.13 to -5.66) 0.006
Self image
3 months -4.83(+/-28.08) -4.17(+/-25.07) -0.67(-11.00 to 9.67) 0.898
6 months -9.63(+/-29.46) -5.27(+/-29.94) -4.36(-16.12 to 7.40) 0.464
12 months -21.37(+/-25.13) -5.75(+/-28.24) -15.61(-27.47 to -3.75) 0.011
Intercourse
3 months -20.44(+/-27.48) -14.33(+/-29.83) -6.11(-17.79 to 5.56) 0.301
6 months -15.77(+/-26.52) -14.41(+/-27.09) -1.36(-12.72 to 10.01) 0.813
12 months -21.11(+/-32.86) -22.42(+/-30.18) 1.31(-12.91 to 15.53) 0.855
*Unpaired t test
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Discussion
In this randomised trial, both excision and vaporisation result in improvements in pain
and health related quality of life up to 12 months. However, when the extent of
improvement is considered, excision is statistically significantly superior.
For proportional improvement this trial confirms the findings of Sutton and Abbott.
Sutton (1) reports 62.5% of women with mild or moderate endometriosis having
improvement in dysmenorrhoea 6 months after laser vaporisation compared with
58.7% in this trial at 6 months. This study finding that 73.2% of women in the excision
group reported EHP 30 core pain score improvement at 6 months, is also similar to
the findings of Abbott’s trial (2), where 80% of women reported some improvement.
However for extent of improvement, this study shows that excision is significantly
better for treating deep disease than vaporisation. Vaporisation is not only
significantly comparatively worse than excision, but also gave insignificant
improvement in EHP-30 Core pain score at 12 months versus baseline for deep
disease.
The groups are well balanced other than a greater proportion of women with deep
disease in the excision group which poses no problem since it was found that
vaporisation performed less well for deep disease thereby giving an advantage to the
vaporisation group.
It has been argued that ablation/vaporisation does not remove all of the disease.
Following his randomised trial, Wright (3) theorised that ablative techniques may
leave a greater area of necrotic tissue behind, with increased inflammatory action
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and a higher propensity to develop adhesive disease. In this study vaporisation was
used to destroy all visible lesions until it looked like an excision. However, even this
technique resulted in worse outcomes compared with excision.
VAS scores also showed no difference in the proportion of patients who improved at
any follow-up point. However, vaporisation did not result in improvement at 12
months for CPP and dyschezia. There seems to be no obvious explanation for this
other than the general trend in this study that vaporisation performs less well at 12
months. Excision was also found to perform significantly better than vaporisation in
reducing CPP at 6 and 12 months and a trend towards greater improvement with for
dysmenorrhoea, dyspareunia and dyschezia (table 4). It may be that the failure to
show significance in all symptoms is related to limitations in the performance of visual
analogue scales as Abbott found and commented on in his trial (2). Alternatively, it
may be that women are able to relate better to some questions than others. Perhaps
the notion of CPP is more meaningful than the notion of dyschezia. There appears to
be no clear trend of one symptom improving to a greater extent than another from the
results.
The trend of excision outperforming vaporisation continued into the EHP-30 HRQoL
parameters (table 5). The significantly better improvement in quality of life domains
for excision, mirroring the reduction in pain, presumably reflects the profound effect
that chronic pain has on quality of life. It stands to reason that, as the pain and quality
of life questions in EHP-30 are ones specifically identified by endometriosis sufferers,
then they will improve if the treatment is effective. Again, there appeared to be no
trend of any one domain improving more than any other, and it is not clear why
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sexual intercourse was the only domain that did not result in a statistically significant
difference between excision and vaporisation.
In a prospective observational cohort study of excision treatment (7) , 67% of women
were found to have an improvement in pain up to 2-5 years following surgery for
endometriosis. Our study confirms that there is no drop off in effect at 12 months for
women who underwent excision, and it is possible that it continues to improve
beyond 12 months post surgery. In contrast, Sutton et al followed up on their 1994
trial and reported that 90% of those patients who had shown pain improvement at 6
months had reported continued benefit at 12 months, suggesting a small drop off in
the effect of vaporisation, though this was no longer part of the blinded trial (8). In this
study, the proportion of patients with improved dysmenorrhoea score (the best direct
comparison with the Sutton results) increased from 58.7 at 6 months to 63.4% at 12
months, but stayed the same for EHP-30 Core pain score (72.7% versus 72.9%).
This does not confirm this possible drop off effect. However, whilst the extent of
score improvement in EHP-30 and dysmenorrhoea continued to improve in the
excision group from 6 months to 12 months, this did not occur in the vaporisation
group, again suggesting that vaporisation is struggling to maintain its effect at 12
months compared with excision.
Finally, it should be noted that the absolute improvement in pain in this study was no
better than a mean -23.9 point drop on the 100 point EHP-30 Core pain scale at 12
months (from a baseline mean of 42.3 to 18.4, or a 56.5% drop in pain score), and a
concerning number of patients reported being either the same or worse. Abbott et al
also found 20% of the patients in his study stayed the same or got worse (2). It is
probable in these cases that it is not the surgery that is causing symptoms to worsen.
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Recurrence of new, or progression of residual lesions are both possible culprits.
Sutton found that only 2 of the 5 women with continued pain following laser treatment
were found to have visually confirmed endometriosis at the 2nd look laparoscopy (1).
The other possibility is that pelvic pain in these women is caused by other
pathologies with similar symptoms like adenomyosis, irritable bowel syndrome or
interstitial cystitis.
If the range of improvement in pain scores was narrow then the moderate extent of
pain improvement achieved would call into question whether subjecting patients to
surgery is indeed worth it. However, the ranges of improvement are wide, with some
patients showing extensive improvement and others showing very little, none, or
becoming worse; this implies that we need to have better prognostic indicators to
select out those who will truly benefit from surgical treatment of endometriosis.
The current randomised data only tells of improvement for a year, which brings into
question the cost-benefit of endometriosis surgery, especially when there is at least a
third risk of recurrent surgery within five years (7). The extent of improvement
resulting from excision beyond 12 months still remains unclear as no randomised
data exists, and is likely to be confounded by other variables introduced over time
following the index surgery.
Conclusions
Contrary to expectation, the extent of improvement in both pain and quality of life is
significantly better for excision than vaporisation at 12 months post-operation. In
addition to this, vaporisation does not convey significant improvement for deep
disease at 12 months. The statistical analysis very much set out to try and disprove
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this finding as it was contrary to the hypothesis at the outset. Since diagnosing deep
endometriosis is essentially an intra-operative one, and since excision will give the
best results in minimal to moderate disease, it makes logical sense to approach
treatment intending to excise in every case.
References
1. Sutton CJ, Ewen SP, Whitelaw N, Haines P. Prospective, randomized, double-blind,
controlled trial of laser laparoscopy in the treatment of pelvic pain associated with minimal,
mild, and moderate endometriosis. Fertil Steril. 1994 Oct;62(4):696-700.
2. Abbott J, Hawe J, Hunter D, Holmes M, Finn P, Garry R. Laparoscopic excision of
endometriosis: a randomized, placebo-controlled trial. Fertil Steril. 2004 Oct;82(4):878-84.
3. Wright J, Lotfallah, H., Lovell, D., Jones, K. A randomised trial of excision vs
ablation for the management of mild endometirosis. Fertil Steril. 2005;83(6):1830-36.
4. Redwine DB. The visual appearance of endometriosis and its impact on our concepts
of disease. Prog Clin Biol Res. 1990;323:393-412.
5. Jones G, Kennedy S, Barnard A, Wong J, Jenkinson C. Development of an
endometriosis quality-of-life instrument: The Endometriosis Health Profile-30. Obstet
Gynecol. 2001 Aug;98(2):258-64.
6. Jones G, Jenkinson C, Kennedy S. Evaluating the responsiveness of the Endometriosis
Health Profile Questionnaire: the EHP-30. Qual Life Res. 2004 Apr;13(3):705-13.
7. Abbott JA, Hawe J, Clayton RD, Garry R. The effects and effectiveness of
laparoscopic excision of endometriosis: a prospective study with 2-5 year follow-up. Hum
Reprod. 2003 Sep;18(9):1922-7.
8. Sutton CJ, Pooley AS, Ewen SP, Haines P. Follow-up report on a randomized
controlled trial of laser laparoscopy in the treatment of pelvic pain associated with minimal to
moderate endometriosis. Fertil Steril. 1997 Dec;68(6):1070-4.
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Table/figure Legends
Table 1. Baseline variables: a comparison of mean baseline variables and a
comparison of mean starting scores for superficial and deep disease.
Table 2. Primary outcome measure analysis: extent of improvement in EHP-30
Core pain score against baseline for excision and vaporisation alone at
12 months and comparative extent of improvement in EHP-30 Core
pain score against baseline for excision and vaporisation at all follow-up
points.
Table 3. Comparison of the extent of improvement in EHP-30 Core pain score
for excision and vaporisation with deep and superficial disease at 12
months against baseline.
Table 4. Extent of comparative improvement for VAS symptom scores for
excision and vaporisation at all follow up points.
Table 5. Comparative extent of score improvement in EHP-30 HRQoL outcome
measures for excision and vaporisation at all follow up points.
Fig 1. Flow diagram of participants through the trial.
Fig 2. Graph of mean improvement in EHP-30 Core pain score against time
for excision and vaporisation.
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