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Article of the week: Remote ischaemic preconditioning reduces injury during partial nephrectomy

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Every week the Editor-in-Chief selects the Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

Finally, the third post under the Article of the Week heading on the homepage will consist of additional material or media. This week we feature a video by Dr. Huang and colleagues to accompany their article.

If you only have time to read one article this week, it should be this one.

Effect of remote ischaemic preconditioning on renal protection in patients undergoing laparoscopic partial nephrectomy: a ‘blinded’ randomised controlled trial

Jiwei Huang, YongHui Chen, Baijun Dong, Wen Kong, Jin Zhang, Wei Xue, DongMing Liu and Yiran Huang

Department of Urology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China

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OBJECTIVE

• To evaluate whether remote ischaemic preconditioning (RIPC) reduces renal injury in patients undergoing laparoscopic partial nephrectomy (LPN).

PATIENTS AND METHODS

• In all, 82 patients undergoing LPN were randomly assigned to either the RIPC or control group, with 40 and 38 patients, respectively completing 6-months follow-up.

•  RIPC was conducted after induction of anaesthesia, which consisted of three 5-min cycles of right lower limb ischaemia and 5 min of reperfusion during each cycle.

•  The primary outcome was the absolute change in glomerular filtration rate (GFR) of the affected kidney by renal scintigraphy from baseline to 6 months.

•  The secondary outcomes included urinary retinol-binding protein (RBP) levels measured at 24 and 48 h, serum creatinine, and estimated GFR (eGFR) at 1 and 6 months, and changes in GFR by renal scintigraphy.

RESULTS

•  There were no differences in the change of GFR of the affected kidney at 6 months, while it was significantly decreased by 15.0% in the control group vs 8.8% in the RIPC group at 1 month (P = 0.034).

•  The urinary RBP levels increased 8.4-fold at 24 h in the control group compared with a lower increase of 3.9-fold in the RIPC group (P < 0.001).

•  There were no differences in the serum creatinine level or eGFR at 1 and 6 months between the two groups.

CONCLUSIONS

•  In patients undergoing LPN, RIPC using transient lower limb ischaemia may reduce renal impairment in the short term, but failed in the longer term despite a non-significant trend in favour of RIPC.

•  These novel data support the need for a larger study of RIPC during LPN surgery.

 

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Editorial: Accepting the positive results of unconventional methods

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It is sometimes difficult to accept the results of a study based on a concept that is unfamiliar, involves unknown physiological mechanisms, or shows results that defy rational explanation. Remote ischaemic preconditioning (RIPC) is probably not a familiar topic to most urologists and, admittedly, was not familiar to this reviewer until now. Yet the authors, based on animal models and clinical data from non-urological literature, conducted a prospective, surgeon and patient ‘blinded’, randomised controlled trial to evaluate the potential benefit of RIPC in minimising ischaemic damage. By most available factors affecting postoperative renal function (warm ischaemia time, tumour complexity as measured by Preoperative Aspects and Dimensions Used for an Anatomical [PADUA] scores, preoperative renal function, tumour stage, etc.), no difference existed between the control and study groups. The authors found that patients undergoing RIPC had a lower change in estimated GFR (eGFR) at 1 month and appeared to have less ischaemic damage based on urinary marker levels (retinol binding protein) and functional imaging parameters. Unfortunately, the short-term benefit of RIPC did not translate to improvements over a longer period, with no differences at 6 months or in absolute eGFR between the two groups.

The authors should be congratulated for conducting such an elegant trial, unfamiliar and unconventional as the concept may be. Strengths of this study include its randomised ‘blinded’ design, correlation with metabolite, urinary marker and imaging findings, 6-month follow-up, and due diligence for assessing most pre-analytic factors. Limitations include the absence of data on residual functioning renal parenchyma, which arguably is the single best predictor of function in an operated kidney; additionally, this population with outstandingly good renal function (≈120 mL/min/1.73 m2 in both groups) with very few comorbidities (<5–10% incidence of hypertension and diabetes) may not translate equally to the less healthy, more renally impaired Western population. The results may appear to be underwhelming, but I agree with the authors that further study is needed, and in particular for the Western population. The major impact from this reviewer’s perspective is for the patient with baseline renal compromise, whose risk for short- and long-term ischaemic renal injury is greater, and who could most benefit from a simple protective measure. Should we now enter unfamiliar territory and accept that the results of a randomised, ‘blinded’, prospective trial of a simple but unconventional method provide sufficient justification for testing this strategy in a higher risk population?

Surena F. Matin
Department of Urology, University of Texas MD Anderson Cancer Center, Houston, TX, USA

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Video: Remote ischaemic preconditioning: good for the short term

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Effect of remote ischaemic preconditioning on renal protection in patients undergoing laparoscopic partial nephrectomy: a ‘blinded’ randomised controlled trial

Jiwei Huang, YongHui Chen, Baijun Dong, Wen Kong, Jin Zhang, Wei Xue, DongMing Liu and Yiran Huang

Department of Urology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China

Read the full article
OBJECTIVE

• To evaluate whether remote ischaemic preconditioning (RIPC) reduces renal injury in patients undergoing laparoscopic partial nephrectomy (LPN).

PATIENTS AND METHODS

• In all, 82 patients undergoing LPN were randomly assigned to either the RIPC or control group, with 40 and 38 patients, respectively completing 6-months follow-up.

•  RIPC was conducted after induction of anaesthesia, which consisted of three 5-min cycles of right lower limb ischaemia and 5 min of reperfusion during each cycle.

•  The primary outcome was the absolute change in glomerular filtration rate (GFR) of the affected kidney by renal scintigraphy from baseline to 6 months.

•  The secondary outcomes included urinary retinol-binding protein (RBP) levels measured at 24 and 48 h, serum creatinine, and estimated GFR (eGFR) at 1 and 6 months, and changes in GFR by renal scintigraphy.

RESULTS

•  There were no differences in the change of GFR of the affected kidney at 6 months, while it was significantly decreased by 15.0% in the control group vs 8.8% in the RIPC group at 1 month (P = 0.034).

•  The urinary RBP levels increased 8.4-fold at 24 h in the control group compared with a lower increase of 3.9-fold in the RIPC group (P < 0.001).

•  There were no differences in the serum creatinine level or eGFR at 1 and 6 months between the two groups.

CONCLUSIONS

•  In patients undergoing LPN, RIPC using transient lower limb ischaemia may reduce renal impairment in the short term, but failed in the longer term despite a non-significant trend in favour of RIPC.

•  These novel data support the need for a larger study of RIPC during LPN surgery.

Article of the week: No difference in sexual function seen between monopolar and bipolar TURP

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Every week the Editor-in-Chief selects the Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

If you only have time to read one article this week, it should be this one.

Bipolar vs monopolar transurethral resection of the prostate: evaluation of the impact on overall sexual function in an international randomized controlled trial setting

Charalampos Mamoulakis1,2, Andreas Skolarikos3, Michael Schulze4, Cesare M. Scoffone5, Jens J. Rassweiler4, Gerasimos Alivizatos3, Roberto M. Scarpa5 and Jean J.M.C.H. de la Rosette1

1Department of Urology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands, 2Department of Urology, University Hospital of Heraklion, University of Crete Medical School, Heraklion, Crete, Greece, 3Second Department of Urology, Sismanoglio Hospital, University of Athens Medical School, Athens, Greece, 4Department of Urology, SLK Kliniken Heilbronn, University of Heidelberg, Heilbronn, Germany, and 5Department of Urology, San Luigi Hospital, University of Turin, Orbassano, Turin, Italy

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OBJECTIVE

• To compare monopolar and bipolar transurethral resection of the prostate (M-TURP and B-TURP, respectively) using a true bipolar system, for the first time in an international multicentre double-blind randomized controlled trial focusing on the overall sexual function quantified with the International Index of Erectile Function Questionnaire (IIEF-15). Other baseline/perioperative parameters potentially influencing erectile function (EF) after TURP were secondarily investigated.

MATERIALS AND METHODS

• From July 2006 to June 2009, consecutive TURP candidates with benign prostatic obstruction were prospectively recruited in four academic urological centres, randomized 1:1 into M-TURP/B-TURP arms and followed up at 6 weeks, 6 and 12 months after surgery. In all, 295 eligible patients were enrolled.

• Overall sexual function was quantified using self-administered IIEF-15 at baseline and at each subsequent visit.

•  Total IIEF/domain scores were calculated and EF score classified erectile dysfunction severity. Differences in erectile dysfunction severity at each visit compared with baseline (EF evolution), classified patients into ‘improved’, ‘stable’ or ‘deteriorated’.

•  Pre-postoperative IIEF/domain scores and differences in the distribution of EF evolution were compared between arms throughout follow-up.

RESULTS

• In all, 279 patients received the allocated intervention; 218/279 patients (78.1%) provided complete IIEF-15 data at baseline and were considered in sexual function analysis. Complete IIEF-15 data were available from 193/218 (88.5%), 186/218 (85.3%) and 179/218 (82.1%) patients at 6 weeks, 6 months and 12 months, respectively.

• Sexual function did not differ significantly between arms during follow-up (scores: IIEF, P = 0.750; EF, P = 0.636; orgasmic function, P = 0.868; sexual desire, P = 0.735; intercourse satisfaction, P = 0.917; overall satisfaction, P = 0.927).

• Resection type was not a predictor of any sexual function changes observed.

• Distribution of EF evolution did not differ between arms at any time (M-TURP vs B-TURP at 12 months: improved, 23/87 [26.4%] vs 18/92 [19.6%]; stable, 53/87 [60.9%] vs 56/92 [60.8%]; deteriorated, 11/87 [12.7%] vs 18/92 [19.6%]; P = 0.323).

CONCLUSION

• There were no differences between M-TURP/B-TURP in any aspect of sexual function.

 

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Editorial: Equivalent outcomes for monopolar and bipolar TURP; but are we overlooking the potential for improvement in sexual function after surgery?

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Both BPH and sexual function (SF) have a major impact on quality of life in older men. Sexual dysfunction is a complex process encompassing both erectile and ejaculatory dysfunction, as well as reduced libido and difficulty achieving orgasm. Whilst retrograde ejaculation is an almost inevitable consequence of TURP, the evidence that TURP causes erectile dysfunction is conflicting. This is probably attributable, at least in part, to a lack of high-quality historical data. Studies now show that LUTS is a risk factor for sexual dysfunction, and we are becoming increasingly aware of the relationship that exists between LUTS, depression and sexual dysfunction.

Given the favourable safety profile of bipolar TURP (b-TURP), it is perhaps a surprise that this latest study from Mamoukalis et al. has failed to demonstrate any difference in outcomes with regard to the deterioration in SF after surgery. The authors should be praised for their attempts to examine in fine detail (using the International Index of Erectile Function [IIEF]-15 in this case) any potential differences between b-TURP and monopolar TURP (m-TURP).

The design of the bipolar system is such that tissue is removed at a lower temperature and therefore the likelihood of damage to surrounding tissues and nerves is reduced. Several randomized trials have compared b-TURP with m-TURP, but only a small number have looked specifically at sexual variables in a randomized setting. This multicentre study by Mamoukalis et al. randomized 279 men to one of the two resection techniques, looking specifically at overall SF quantified by the IIEF-15. No differences were detected in any aspect of SF; erectile function (EF) improved in 26.4% of patients in the m-TURP group compared with 19.6% in the b-TURP group, and remained stable in 60.9 and 60.8% of patients, respectively. A deterioration in EF was apparent in 12.7% of the m-TURP group compared with 19.6% of the b-TURP group (P = 0.323). These results mirror those of a similar randomized study by Akman et al. comparing a quasi-bipolar system with m-TURP. They demonstrated equivalence for all measured variables except for operating time and a 1.4% incidence of TUR syndrome in the m-TURP group. In their study, the EF domain of the IIEF-15 was measured before and after surgery. EF worsened in 17% of men, improved in 28.2% and was unchanged in 54.8%. A comparative evaluation of EF was performed in a sub-group of 188 sexually active non-catheterized men of whom 18.2% developed de novo erectile dysfunction.

The explanation for the equivalent outcomes is unclear and further investigation is required. Does the failure of bipolar TURP to demonstrate a benefit with regard to SF leave the door open for the competing minimally invasive laser technologies? The overall impact of the holmium laser compared with that of TURP appears to be equivalent, with a mean of 7.5 and 7.7% of patients reporting decreased erectile function, and 7.1 and 6.2% of patients reporting increased function after each surgery. From the data available thus far, it would also appear that photoselective vaporization of the prostate similarly has no overall deleterious impact on SF when compared with TURP in a randomized trial. Further randomized data are pending and are of course of great importance if we are to understand better how the procedures we perform for symptomatic BPH affect our patients. As technological advances are made the hope is that the ‘damaging’ effects of BPH surgery on overall SF (particularly EF) will reduce further, but it may indeed be that we are searching for small margins when our attention might be better focused on maximizing the likelihood of a positive outcome, facilitated by considering the preoperative status (general health as well as urinary and sexual function), aided by the use of validated questionnaires. A better appreciation and understanding of the factors that may increase the risk of ED after surgery (age, diabetes, metabolic syndrome, obesity, cardiovascular disease and psychological factors) will enable us to manage expectations more effectively. A shorter hospital stay with minimal postoperative discomfort and an early return to normal activities, coupled with good symptomatic improvement in the longer term can only serve to be of benefit with regard to improving SF outcomes.

One recent study reporting both the short-, medium- and long-term effects of TURP on SF highlighted the high incidence of LUTS before treatment with 57% overall reporting ED before surgery. Those with severe LUTS were much more likely to have significant sexual dysfunction before surgery. This study also demonstrated a 15% improvement in pre-existing ED which was related to the improvement in LUTS after TURP.

On reflection, therefore, it would seem reasonable to conclude from the evidence presented that, although retrograde ejaculation frequently occurs after outflow surgery, erectile function is as likely to improve as it is to deteriorate. By focusing on the specific patient characteristics for each individual case before surgery it is possible we can improve the proportion of patients achieving a favourable outcome. When counselling patients before surgery regarding SF we should therefore remember to include the potential benefits as well as the risks. Furthermore, for those patients particularly anxious about the possibility of worsening SF, a ‘lesser’ surgical procedure, which might not achieve a transurethral resection-like cavity should perhaps be considered as a compromise. However, a surgical alternative which is not equivalent to TURP may indeed reduce the likelihood of improving erectile function, given the interrelationship that appears to exist between LUTS and SF.

Richard Hindley
Department of Urology, Hampshire Hospitals NHS Foundation Trust, Basingstoke, Hampshire, UK.

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Article of the week: Dutch GPs influenced by ERSPC PSA study

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Every week the Editor-in-Chief selects the Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

Finally, the third post under the Article of the Week heading on the homepage will consist of additional material or media. This week we feature a video of Miss van der Meer and Dr Blanker discussing their article.

If you only have time to read one article this week, it should be this one.

Impact of the European Randomized Study of Screening for Prostate Cancer (ERSPC) on prostate-specific antigen (PSA) testing by Dutch general practitioners

Saskia Van der Meer, Boudewijn J. Kollen*, Willem H. Hirdes, Martijn G. Steffens, Josette E.H.M. Hoekstra-Weebers†, Rien M. Nijman‡ and Marco H. Blanker*

Department of Urology, Isala Clinics, Zwolle, and Departments of *General Practice, †Psychosocial services and ‡Urology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands

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OBJECTIVE

• To determine the impact of the European Randomized Study of Screening for Prostate Cancer (ERSPC) publication in 2009 on prostate-specific antigen (PSA) level testing by Dutch general practitioners (GPs) in men aged ≥40 years.

MATERIALS AND METHODS

• Retrospective study with a Dutch insurance company database (containing PSA test claims) and a large district hospital-laboratory database (containing PSA-test results).

• The difference in primary PSA-testing rate as well as follow-up testing before and after the ERSPC was tested using the chi-square test with statistical significance at P < 0.05.

RESULTS

• Decline in PSA tests 4 months after ERSPC publication, especially for men aged ≥60 years.

• Primary testing as well as follow-up testing decreased, both for PSA levels of <4 ng/mL as well as for PSA levels of 4–10 ng/mL.

• Follow-up testing after a PSA level result of >10 ng/mL moderately increased (P = 0.171).

• Referral to a urologist after a PSA level result of >4 ng/mL decreased slightly after the ERSPC publication (P = 0.044).

CONCLUSIONS

• After the ERSPC publication primary PSA testing as well as follow-up testing decreased.

• Follow-up testing seemed not to be adequate after an abnormal PSA result. The reasons for this remain unclear.

 

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Editorial: Impact of ERSPC study on PSA testing in the Netherlands

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General practitioner (GP)’s view on screening for prostate cancer in the Netherlands: the impact of a randomized trial

I am grateful to be given the opportunity to provide an editorial comment on a so-far unique publication investigating the impact of results of the European Randomized study of Screening for Prostate Cancer (ERSPC) on the attitude of Dutch GPs in requesting a serum determination of PSA in men aged >40 years. Access to data from one of the major health insurance companies and the structure and data acquisition of regional laboratories in the Netherlands provided an opportunity to carry out the project. This included the differentiation of age groups, of primary as opposed to repeat PSA testing and, in the case of the hospital database, of repeat PSA testing within 1 year, which provided the opportunity to address the primary goal of the study: the evaluation of the difference in primary PSA testing rates as well as follow-up testing before and after the 2009 publication of interim data from the ERSPC study. The fact that a Dutch translation of this publication and a recommendation by the Dutch Association of General Practitioners (Nederlands Huisartsen Genootschap, NHG) were mailed at the same time and the fact that GP guidelines had not been changed since 2005 in the Netherlands provided an important basis for the reported study.

Two different databases were used and PSA testing was evaluated 1 year before and 1 year after March 2009 (excluding the month March 2009). An overview of the data acquisition and results is given in Table 1. In brief, the data based on insurance claims show a significant decrease in PSA use before and after the 2009 publication. This decrease was less pronounced or not seen at all in men aged 70–80 or >80 years. The study selectively identified men in the ERSPC region of Rotterdam after exclusion of those assigned for re-testing in the screening arm. In line with earlier investigations, the PSA testing rate in the Rotterdam region was considerably higher then in the rest of the Netherlands. This effect was blamed on increased awareness and possibly on the motivation of men randomized into the control group of the study. The so-called ‘hospital database’ refers to a regional GP laboratory. It remains unexplained why only 2098 men of the total of 9766 men who were identified as having undergone primary PSA testing (Tables 1 and 2 in the study) were included in the analysis. These data show that there was no overall difference in testing before and after the ERSPC publication, but the proportion of re-testing decreased significantly between the two periods.

Table 1: Data acquisition and results.

Several comments can be made on this study. First, information provided on the insurance claims database allows an estimate of the proportion of men in whom PSA is evaluated (123 996/715 000 = 17.3%) and of those who undergo primary PSA testing for early diagnostic purposes (66 848/715 000 = 9.4%). The overall figure contrasts sharply with the results of a study by the Central Bureau of Statistics in the Netherlands, published in 2006. The study shows PSA use of 30–40% for the age groups 60–70 years or older.

Second, as the authors acknowledge, the differentiation between primary PSA tests for the purpose of early diagnosis and for other purposes may not be entirely reliable; however, the bias resulting from possibly incorrect assumptions is likely to be small.

Third, the sub-analysis of data coming from the Rotterdam region is likely to show the impact of greater awareness resulting from written informed consent before randomization and the effect of randomization into a control group. The data confirm an earlier evaluation of this subject (reference 7 in Van der Meer et al.) and at the same time provide a rough estimate of the level of contamination which may take place in the ERSPC study, Rotterdam region.

Fourth, it is interesting to see how age and previous PSA values influence the request for repeat PSA studies. It is counterintuitive (Table 3 in Van der Meer et al.) that even in the critical PSA range 4–10 ng/mL a significant decrease of PSA use within 1 year was seen. The multivariate analysis shows that study period before and after 2009, PSA categories and age groups are all significantly related to the decrease of PSA re-testing within 1 year.

Finally, as one of the initiators of the ERSPC study, I should like to refer to two important follow-up publications (Schröder et al., Heijnsdijk et al.) that point to the over-diagnosis and over-treatment of prostate cancer as the main reasons why the almost 30% reduction in prostate cancer mortality in screened men cannot (yet) be used for establishing population-based screening. For these reasons, the authors fully agree with the viewpoint of the Dutch GP Association and the recommendation against routine use of PSA-driven screening for prostate cancer; however, as pointed out in the last sentences of their paper instruments are now available to decrease over-diagnosis and the rate of unnecessary biopsies. In addition to that, it should be realized that men who are well informed and wish to be tested for prostate cancer cannot be refused PSA testing. To assist this process, the International Society of Urology (SIU) and the international movement ‘Movember’ have recently made available on their websites a validated decision aid for men who wish to be tested, their GPs and their treating urologists.

Fritz H. Schröder
Erasmus Medical Center, Rotterdam, The Netherlands.

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Video: PSA testing decreased in the Netherlands after ERSPC study

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Impact of the European Randomized Study of Screening for Prostate Cancer (ERSPC) on prostate-specific antigen (PSA) testing by Dutch general practitioners

Saskia Van der Meer, Boudewijn J. Kollen*, Willem H. Hirdes, Martijn G. Steffens, Josette E.H.M. Hoekstra-Weebers†, Rien M. Nijman‡ and Marco H. Blanker*

Department of Urology, Isala Clinics, Zwolle, and Departments of *General Practice, †Psychosocial services and ‡Urology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands

Read the full article
OBJECTIVE

• To determine the impact of the European Randomized Study of Screening for Prostate Cancer (ERSPC) publication in 2009 on prostate-specific antigen (PSA) level testing by Dutch general practitioners (GPs) in men aged ≥40 years.

MATERIALS AND METHODS

• Retrospective study with a Dutch insurance company database (containing PSA test claims) and a large district hospital-laboratory database (containing PSA-test results).

• The difference in primary PSA-testing rate as well as follow-up testing before and after the ERSPC was tested using the chi-square test with statistical significance at P < 0.05.

RESULTS

• Decline in PSA tests 4 months after ERSPC publication, especially for men aged ≥60 years.

• Primary testing as well as follow-up testing decreased, both for PSA levels of <4 ng/mL as well as for PSA levels of 4–10 ng/mL.

• Follow-up testing after a PSA level result of >10 ng/mL moderately increased (P = 0.171).

• Referral to a urologist after a PSA level result of >4 ng/mL decreased slightly after the ERSPC publication (P = 0.044).

CONCLUSIONS

• After the ERSPC publication primary PSA testing as well as follow-up testing decreased.

• Follow-up testing seemed not to be adequate after an abnormal PSA result. The reasons for this remain unclear.

 

Article of the week: Botulinum toxins are not interchangeable for overactive bladder

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Every week the Editor-in-Chief selects the Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

Finally, the third post under the Article of the Week heading on the homepage will consist of additional material or media. This week we feature a video of Miss Ravindra and colleagues discussing their article.

If you only have time to read one article this week, it should be this one.

Botulinum toxin type A for the treatment of non-neurogenic overactive bladder: does using onabotulinumtoxinA (Botox®) or abobotulinumtoxinA (Dysport®) make a difference?

Pravisha Ravindra, Benjamin L. Jackson and Richard J. Parkinson

Nottingham Urology Centre, Nottingham University Hospitals, NHS Trust, Nottingham, UK

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OBJECTIVE

• To compare the clinical effects of two different commercially available botulinum toxin type A products, onabotulinumtoxinA (Botox®; Allergan Inc., Irvine, CA, USA) and abobotulinumtoxinA (Dysport®; Ipsen Ltd, Slough, UK), on non-neurogenic overactive bladder (OAB).

PATIENTS AND METHODS

• We included 207 patients, who underwent treatment with botulinum toxin type A for non-neurogenic OAB from January 2009 to June 2012 at our institution, in a prospective database that recorded details of their presentation, treatment and outcomes.

• In December 2009, our institution switched from using onabotulinumtoxinA to using abobotulinumtoxinA.

RESULTS

• Results from the onabotulinumtoxinA cohort (n = 101) and the abobotulinumtoxinA cohort (n = 106) were compared.

• Similar reductions in daytime frequency, nocturia and incontinence episodes were observed after treatment, with no difference in duration of effect.

• The abobotulinumtoxinA cohort had almost twice the rate of symptomatic urinary retention (23 vs 42%) requiring intermittent self-catheterisation (ISC).

CONCLUSIONS

• AbobotulinumtoxinA use was complicated by a significantly higher risk of requiring ISC.

• The study suggests that these two toxins are not interchangeable at the doses used.

 

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Editorial: Botulinum toxin-A for overactive bladder: formulations, dosing and clean intermittent catheterisation

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The article by Ravindra et al., in this issue of the BJUI, tries to address an important question of comparing the 2 commonest types of botulinum toxin-A (BTX-A), Ona- and AbobotulinumtoxinA. In their institution they changed from OnbotulinumtoxinA to AbobotulinumtoxinA and thus compared results of their different case series for patients with overactive bladder syndrome. Very few studies have tried to address this issue for botulinum toxin-A use in the urinary tract and to my knowledge there are no head to head studies. The authors found the 2 types of BTX-A equivalent in terms of voiding diary parameters, ICIQ questionnaires, patient reported global satisfaction and duration of effect but noted a significant difference for clean intermittent self catheterisation (CISC) rates (23% OnabotulinutoxinA vs 42% AbobotulinumtoxinA). The dose used for OnabotuliumtoxinA was 200 IU and for AbobotulinumtoxinA was 500 IU initially and then later 300 IU. One must bear in mind some important considerations which limit the impact of the result. Namely the non-randomised, retrospective nature of the study and the fact that the study was not designed or powered to assess the BTX-A formulations in this way. The primary endpoint in this case was a patient reported satisfaction measure indicating that 85% had ‘better’ or ‘much better’ symptoms which I think is a fair reflection in my experience. Furthermore there were significant gaps in data acquisition particularly for voiding diary, PVR and ICIQ data which again is not that uncommon in retrospective studies. No urodynamic data was included which I think may also have been interesting to look at when assessing outcomes and CISC rates.

None the less the study generates some interesting discussion about the formulations, optimal dosing and the dosing equivalence. The study is one of the first to report on the use of AbobotulinumtoxinA at 300 IU as most studies utilised 500 IU. In view of the move to lower doses of OnabotulinumtoxinA to treat refractory OAB of 100–150 IU, this dose seems appropriate. Evidence from a large dose ranging RCT using OnabotulinumtoxinA suggests no further efficacy beyond doses of 150 IU but an increase in voiding dysfunction. Interestingly CISC rates are still high at 300 IU in this study. A recent systematic review tried to assess the 2 formulations in aspects of BTX-A use for various lower urinary tract dysfunction. Due to the heterogenousity of the studies, a lack of standardised or high quality data a direct comparison between the 2 was not formally possible. It was noted that OnabotulinumtoxinA has been studied more extensively compared to AbobotulinumtoxinA and with both formulations CISC rates could be high at the doses used in this study (OnabotulinumtoxinA 43%; AbobotulinumtoxinA 35%). Assessing the compound muscle action potential of the extensor digitorum brevis muscle in healthy volunteers has suggested an AbobotulinumtoxinA to OnabotulinumtoxinA ratio of 1.57:1 (95% confidence interval: 0.77–3.20 units) with the data indicating that a dose-equivalence ratio of 3:1 was just within statistical error limits but ratios over 3:1 were too high. The same author following a review of the literature in treatments outside the urinary tract suggest a ratio of 2–2.5:1 maybe the most appropriate. An animal model of spinal cord injury and neurogenic detrusor overactivity to compare the 2 formulations has recently been published. The minimal effective dose of Abo- and OnabotulinumtoxinA was found to be 10 IU and 7.5 IU, respectively, for significant changes in cystometry.

When should CISC be instigated? Practice seems to vary considerably and thus results difficult to compare. Many clinicians will base CISC decisions on a cut off, typically 100–200 mL or on whether patients are symptomatic with their PVR. Chapple has suggested >40% of the functional capacity as a significant PVR and this to me seems entirely logical. Future studies should consider this as an endpoint regarding CISC.

At present, the decision as to which formulation is used in clinical practice is often based on local pharmacy regulation and financial considerations. Licensing is undoubtedly going to have a significant influence on this practice. OnabotulinumtoxinA is now licensed for use in many parts of the world to treat neurogenic detrsuor overactivity and has recently been approved by the FDA in the USA to treat refractory OAB. At the time of writing this editorial, no formulation is currently approved for refractory OAB in the UK.

Arun Sahai
Consultant Urologist & Honorary Senior Lecturer, Department of Urology, Guy’s Hospital MRC Centre for Transplantation, King’s College London, King’s Health Partners

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