Surgical treatments for men with benign prostatic enlargement: cost effectiveness study
BMJ 2009; 338 doi: https://doi.org/10.1136/bmj.b1288 (Published 16 April 2009) Cite this as: BMJ 2009;338:b1288
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The authors in the cost effectiveness study made several assumptions
(1). I have stated some in a previous response. The authors identified
transurethral microwave thermotherapy (TUMT) and diathermy vaporisation
(TUVP) as typifying the minimally invasive and tissue ablative groups,
respectively. Both treatment modalities are very uncommonly used in
modern practice. The authors based their appraisal regarding the
effectiveness of treatment on two systematic reviews (2, 3). These
systematic reviews had set the primary outcome measure as the change in
symptom score at 12 months after surgery. The follow-up is too short to
be meaningful (4). The rules that the authors designed “minimally
invasive treatments could be repeated only once; tissue ablative and
holmium laser enucleation procedures could not be repeated because of the
effect on remaining prostate tissue and near total removal, respectively”
are most unusual indeed. The treatment strategies (table 1 in the
article) are at best illogical.
In addition, setting the cycle length
“three months, the period over which benefit would occur and short term
adverse events resolve” is incorrect. It often takes a much longer period
for a final outcome. Incontinence bad enough for the person to seek help
resulting in additional treatment is the only complication included in the
model. However, urethral strictures (2.2-9.8%) and bladder neck
contractures (0.3-9.2%) are late complications that require re-treatment
(5).
The authors acknowledged that long term data were available only for
transurethral resection and microwave thermotherapy. Deriving relapse
rates for other treatments according to the weighted mean difference in
symptom score at 12 months is open to question. If the study design is
flawed, the conclusions are unsound. The suggestion that “initial
diathermy vaporisation followed by either holmium laser enucleation or
transurethral resection, repeated if necessary on failure or relapse, are
cost effective strategies for surgical treatment of symptoms” is bizarre.
The major issue when an a study like this is printed in the BMJ is
that it will get quoted by the less informed in months and years to come.
This is precarious.
References:
1. Armstrong N, Vale L, Deverill M, Nabi G, McClinton S, N’Dow J,
Pickard R, for the BPE Study Group. Surgical treatments for men with
benign prostatic enlargement: cost effectiveness study. BMJ 2009; 338:
b1288
2. Lourenco T, Pickard R, Vale L, Grant A, Fraser C, MacLennan G, et
al. Minimally invasive treatments for benign prostatic enlargement:
systematic review of randomised controlled trials. BMJ 2008;337:a1662
3. Lourenco T, Pickard R, Vale L, Grant A, Fraser C, MacLennan G et
al. Alternative approaches to endoscopic ablation for benign enlargement
of the prostate: systematic review of randomised controlled trials. BMJ
2008;337:a449
4. Elliott SP. Endoscopic ablation for benign enlargement of the
prostate. Newer techniques are no better than transurethral resection, but
the evidence base is poor. BMJ 2008;337: a535
5. Rassweiler J, Teber D, Kuntz R, Hofmann R. Complications of
transurethral resection of the prostate (TURP)--incidence, management, and
prevention. Eur Urol. 2006 ; 50: 969-79; discussion 980.
Competing interests:
None declared
Competing interests: No competing interests
We thank Mr Mishriki for his interest in our study. The editorial
team at BMJ accepted the study following revision subsequent to the
comments of clinical and health economic expert referees. The great
variety of techniques trialled for the ablation of benign prostatic
enlargement did indeed require a degree of conceptual grouping in order to
enable construction of a useful and workable model. Whilst we respect Mr
Mishriki's views we would contend that the final effect of all
technologies is to heat prostatic tissue sufficiently to cause cell death.
The temperature reached will determine whether this causes coagulation or
vaporisation and instrument design will determine whether vaporised tissue
is removed as small particle effluent, piecemeal, or as a complete
adenoma. Given this common basis we felt the treatment groupings to be
reasonable. The definition of failure was set at the minimum change in
symptom score appreciable by an individual undergoing treatment. We agree
that systematic review and meta-analysis of randomised studies has
limitations but it remains the best technique to summarise evidence
regarded as of high quality. The easiest way to improve its scope is to
perform more quality trials and ensure that they are reported
consistently. We acknowledge that the diathermy method of vaporisation is
little used at present, despite a high level of evidence for its
effectiveness, although use of bipolar energy delivery may lead to its
resurgence. We would contend that currently popular vaporisation
techniques must at least equal diathermy in effectiveness and cost to make
a change in practice worthwhile to patients and the NHS. We are sorry that
Mr Mishriki felt our work to be costly and ineffective but we are
encouraged that it provoked this debate.
Competing interests:
None declared
Competing interests: No competing interests
authors admitted that selection between techniques was difficult. Their
assumption that these have the same tissue ablation effect is based on no
evidence. The definition of failure as <10% improvement in symptoms is
at best flawed. Clinical effectiveness data were derived from a
systematic review that had its own limitations [2,3]. The conclusion that
initial vaporisation followed by holmium laser enucleation for failure or
relapse might be advantageous both to patients and healthcare providers is
bizarre. For starters, tissue vaporisation is an almost obsolete
technique. We do not need a Markov model or a Monte Carlo simulation to
conclude that this was a costly ineffective study.
References:
1. BMJ 2009;338:b1288
2. Lourenco T, Pickard R, Vale L, Grant A, Fraser C, MacLennan G, et al.
Minimally invasive treatments for benign prostatic enlargement: systematic
review of randomised controlled trials. BMJ 2008;337:a1662.
3. Lourenco T, Pickard R, Vale L, Grant A, Fraser C, MacLennan G et al.
Alternative approaches to endoscopic ablation for benign enlargement of
the prostate: systematic review of randomised controlled trials. BMJ
2008;337:a449.
Competing interests: No competing interests
We thank Drs Thilagarajah and Ghani for studying our paper and making
some pertinent points. We used the highest quality data available for
defining parameters used in the model. We agree that evidence gaps
concerning KTP laser vaporisation increased the degree of uncertainty
regarding these parameters but additional sensitivity analyses using wide
ranges of parameter values did not change our findings, thus supporting
our conclusions. Concerning repeat vaporisation procedures we were unable
to find any evidence that would allow us to predict the likelihood of
successful outcome. The expert group considered that a repeat procedure
following failure to respond or relapse would not, at present, be
considered as standard management and therefore made the decision not to
include such strategies in the model.
We completely agree that further
high quality trials are needed, particularly using current vaporisation
techniques and 'tracker' methodology does allow for changes in technology
during the trial period. We consider that TURP remains the standard
comparator and a number of recent trials have indeed been successfully
conducted with TURP arms. The use of vaporisation techniques has however
expanded the use of bladder outlet surgery for men with severe co-morbidity or anticoagulant treatment that precludes TURP and therefore
stratified randomisation may also be required. Whilst we acknowledge the
uncertainties regarding the evidence base, KTP laser vaporisation cannot
be considered cost-effective in our model since it is less effective and
more costly than alternative ablative options.
Competing interests:
None declared
Competing interests: No competing interests
I too noticed this slip up. Happily one for the Editor rather than
Author.
Competing interests:
None declared
Competing interests: No competing interests
Oh dear, BMJ.
You have taken the factually correct statement in the introduction to
this article; 'there are 1.8 million cases (of BPE) in the UK', and
changed it into a '1.8 million cases of prostate cancer' headline in your
'The Week in Numbers' feature at the front of the print version!
Competing interests:
None declared
Competing interests: No competing interests
The finding that potassium titanyl phophate (KTP) laser vaporisation
is not cost effective in this study appears to be incorrectly based on
data grouped from a number of diathermy vaporisation techniques. The
previous systematic review quoted in the paper also groups together
therapies including Nd:YAG and interstitial lasers which cannot be used to
assess the efficacy of KTP vaporisation(1). The single eligible trial
comparing KTP with conventional transurethral resection of prostate (TURP)
is also too small to form an opinion concerning the effectiveness of KTP
in this setting(2). It is unfortunate that the diathermy vaporisation
treatment strategy group did not allow for a second treatment in case of
initial failure, as this may have altered the cost effectiveness score of
this treatment when compared with other combinations.
The cost effectiveness of KTP relies on specialist centres carrying
out large numbers of procedures with protocol driven patient care pathways
in place. It remains difficult to recruit patients to randomised studies
(with TURP) as a result of the known complications associated with the
latter. It must also be recognised that these technologies are being
developed and improved at a rapid rate and it is welcomed that the authors
recognise the uncertainties and limitations of the published study in view
of this. The authors’ proposal of longer term “tracker” trials will go
some way towards producing meaningful data for the management of benign
prostatic elargement.
1 Lourenco T, Pickard R, Vale L, Grant A, Fraser C, MacLennan G et
al. Alternative approaches to endoscopic ablation for benign enlargement of the prostate: systematic review of randomised controlled trials. BMJ 2008;337:a449
2 Horasanli K, Silay MS, Altay B, Tanriverdi O, Sarica K, Miroglu C. Photoselective potassium titanyl phosphate (KTP) laser vaporization
versus transurethral resection of the prostate for prostates larger
than 70 ml: a short-term prospective randomized trial. Urology
2008;71:247-51
Competing interests:
None declared
Competing interests: No competing interests
Re: The study is flawed
Whilst we thank Dr Mishriki for his interest and further comments on
our paper, we cannot agree with his opinions regarding dealing with
uncertainty in health economic analysis. Our study was carried out
according to current best practice in systematic review, meta-analysis and
economic modelling and has been subjected to extensive and thorough peer
review. All of the concerns expressed by Dr Mishriki are addressed within
the paper and are covered by appropriate sensitivity analyses including
relapse rate, use of a life-time time horizon, and accounting for adverse
event rates. In addition the text advises cautious interpretation of the
results due to uncertainty created by gaps in the required evidence.
Whilst we do not expect every reader to agree with all of the assumptions
required for the Markov model or indeed our conclusions, some of Dr
Mishriki’s comments suggest a lack of understanding of research
methodology presented in our work. There would seem to be little or no
worth in pursuing further dialogue with Dr Mishriki and the authors are
content to respectfully acknowledge the expressed opinions but not to
debate them further.
Competing interests:
None declared
Competing interests: No competing interests