PENILE PROSTHETIC TRENDS IN THE ERA OF EFFECTIVE ORAL ERECTOGENIC AGENTS
Title: PENILE PROSTHETIC TRENDS IN THE ERA OF EFFECTIVE ORAL ERECTOGENIC AGENTS , By: Stanley, Grant E., Bivalacqua, Trinity J., Hellstrom, Wayne J. G., Southern Medical Journal, 00384348, Dec2000, Vol. 93, Issue 12
Section: CURRENT CONCEPTS
ABSTRACT: Before the introduction of sildenafil for the treatment of erectile dysfunction (ED), penile implants were recognized as the most effective, though most invasive, therapy with a high satisfaction rate. We compared and evaluated trends in penile prosthesis procedures at a tertiary referral center before and after the introduction of sildenafil. We retrospectively reviewed the clinical records of 561 implant procedures over the past 10 years to categorize the operations (eg, simple/”virgin” implant, replacement, revision, removal) and to establish the duration, severity, and complexity of the ED. No significant change was found in the number of penile implant procedures done annually. Both complexity of the procedures and severity of illness increased. A downward trend was seen in the number of simple penile prostheses implanted. Our data suggest that, with an aging population both aware of and requesting therapy for ED, the number of penile implantations will remain stable or increase, especially at centers specializing in ED treatment.
ERECTILE DYSFUNCTION (ED) has been defined as the persistent inability to attain or maintain an erection adequate to permit satisfactory sexual performance.(n1) This disease affects between 20 and 30 million men in the United States.(n2) Treatment of ED usually begins with the least invasive approach, eg, oral medications, and then progresses to more invasive treatments, eg, intracavernosal injections, transurethral delivery of alprostadil (prostaglandin E1), and ultimately penile prostheses.
Before the introduction of sildenafil in March 1998, and currently, penile implants have had the distinction of being the most effective treatment for ED, with a relatively high satisfaction rate. However, the question arises as to the future status of penile prostheses in an era when new oral agents are about to enter the market. The availability of effective noninvasive methods for addressing ED may conceivably reduce the number of patients choosing intracavernosal injections, vacuum devices, and implants for treating impotence . However, as articulated by a number of ED authorities, the success rate of sildenafil is between 50% and 80%, and its introduction has conservatively tripled the number of men seeking treatment for impotence .(n3) Therefore, it may be anticipated that the use of implants will remain prevalent as those in whom sildenafil fails seek out other therapies.
We compared and evaluated the trends in penile prosthesis procedures over the past decade, both before and after the introduction of oral sildenafil. Specifically, our aim was to extrapolate from data to determine whether the number of penile prosthesis procedures will increase, decrease, or remain constant in the future with the introduction of newer, safer, and more efficacious oral medications for the treatment of ED.
MATERIAL AND METHODS
The International Index of Erectile Function Questionnaire(n4) was not available for the majority of cases in this retrospective series; hence, we were unable to quantify the severity of ED using this instrument. However, we defined the severity of ED by the following parameters: (1) the presence and duration of other medical conditions that are associated with an increased risk of ED (eg, heart disease, diabetes, hypertension), (2) the number of years that each prospective patient had had difficulty with erections, and (3) the type and number of other therapeutic options attempted and failed before implantation of a penile prosthesis.
With respect to the complexity of cases, the following terms are defined:
Replacement: Placement of a penile prosthesis during the same operation in which a previously placed implant is removed.
Removal: Removal of a previously placed implant without immediate reimplantation.
Revision: Manipulation of a previously placed implant without removal or replacement.
Simple implant: Placement of a penile prosthesis in a patient who has not previously had implant surgery.
For the purposes of our study, the number of simple implants was determined to be the total number of implants placed, less the number of removals, replacements, and revisions (Table). Theoretically, this may understate or overstate the number of simple implants, because the patients who previously had removals with reinsertion at a later date are not reflected as such in the database used to compile this information. However, these numbers are expected to be materially consistent between periods and should not negatively affect the general trend of such procedures.
The total number of implant procedures during any given period includes both malleable and inflatable prosthesis cases (with the vast majority, as is typical in most American practices, comprised of inflatable penile prostheses), as well as any revisions, removals, or replacements.
We retrospectively reviewed the clinical records of patients who had penile prosthesis surgery at Tulane University Medical Center from January 1990 through December 1999. During the study period, a total of 561 implant procedures were done. The nature of the operation (eg, simple implant, replacement, revision, removal) was categorized and the patients’ medical backgrounds were assessed to identify any medical factors that may have contributed to the severity of the ED. As Feldman et al(n2) have pointed out, medical conditions, including diabetes, heart disease, and hypertension, are significantly associated with increased probability of impotence . Review of patient records allowed us to record the duration and severity of medical conditions.
The raw data on the total number of implants, removals, replacements, revisions, and simple procedures are expressed as mean +/- SE and were analyzed using a one-way analysis of variance with repeated measures and Newman-Keuls test for multiple group comparisons. A value of P < .05 was used as the criterion for statistical significance.
RESULTS
Despite the advent of new safe and efficacious oral medications (eg, sildenafil) for the treatment of ED, there has been no significant change (P > .05) in the frequency or percentage of penile implant procedures done at our medical facilities over the past 10 years. There was an upward trend in the complexity and number of revision procedures in the past 10 years, particularly in the period leading up to and after the release of sildenafil (Table; Figure). The most frequently treated complex cases at our university were those of Peyronie’s disease, which involved placement of an inflatable penile prosthesis and either manual molding or excision of a Peyronie’s plaque and placement of grafting materials.
We found a general downward trend in the number and percentage of simple penile prostheses implanted during the study period. Thus, there was a significantly lower number and percentage of simple penile prosthesis implant procedures 2 years after the advent of sildenafil (P < .05) (Figure). The number and percentage of procedures remained relatively constant after the release of sildenafil in 1998 as compared with previous comparable periods (Table). Because ours is a tertiary referral center, many of the replacements, removals, and revisions were transferred to our institution for follow-up care.
We also saw an increase in the severity of dis-ease treated with penile implants in the period leading up to and subsequent to the introduction of sildenafil. Mean duration of ED increased from 7.3 years in 1991 to 9.2 years in 1999. This was determined by randomly selecting patients from various years within the study period. The duration of ED for each patient was determined by chart review. It was considered to be the period from the patient’s earliest recollection of difficulty in attaining or maintaining an erection to permit satisfactory sexual performance to the date of penile prosthesis implantation.
DISCUSSION
Sildenafil was approved for sale in the United States In March 1998.(n5) Despite this major therapeutic innovation, the number of implant procedures has remained relatively stable at our medical center, and it is expected to remain constant or increase in the future. This phenomenon can be explained by several factors. First, sildenafil is not effective for all cases of ED. Although published studies and package information report an 82% success rate (based on subjective reports of erection improvement) compared with a 24% response in the placebo group, specific populations are recognized as not responding favorably. A compilation of clinical trials revealed that sildenafil improved erections in 43% of patients after radical prostatectomy,(n6) 57% of diabetic patients,(n7) 68% of hypertensive patients, and 61% of patients after transurethral resection of the prostate.(n8) This leaves a significant population who require other more invasive options for the treatment of ED. Additionally, approximately 6 million men are taking nitrates in the United States. Sildenafil is strictly contraindicated in patients using nitrates because it synergistically increases the hypotensive effects of these drugs.
The second reason why the number of implant procedures is expected to remain relatively constant or increase relates to the nature of ED itself. The Massachusetts Male Aging Study(n2) indicates that the prevalence of minor, moderate, and complete ED in the United States is approximately 52% for men between the ages of 40 and 70 years. This landmark study reveals that impotence is an age-related phenomenon and that age is the variable most strongly associated with impotence . The moderate category in this study comprised the highest number of patients (25%), with the minimally and completely impotent classifications representing 17% and 10%, respectively. Likewise, Steers et al(n9) completed meta-analysis of data from 10 double-blind, placebo-controlled studies to evaluate the efficacy of sildenafil in patients with severe ED and found response rates ranging from 46% to 73%. As the population ages, more patients will be expected to shift from the minimally and moderately impotent categories to severely or completely impotent categories. This translates into a larger cohort of patients who will not benefit from oral medication and will become candidates for more invasive ED treatments, such as implants.
There is evidence that ED is a common, untreated condition. In a study by Slag et al,(n10) 53% of men with ED refused evaluation for the problem. According to some authorities, only 2.6% to 5.2% of patients with ED have sought any form of treatment.(n11) With the introduction of less invasive therapies, this number is expected to increase. It can be concluded that with an aging population there will be a higher prevalence of more advanced ED in the future. All of these factors will likely maintain the penile prosthesis option at its present or even an increased frequency.
With the advent of newer and potentially more efficacious therapies, men who had previously refused to seek treatment for impotence because of the invasive or intrusive alternatives (vacuum erection device, penile injections, penile prostheses) will now be more willing to seek evaluation.(n3) In a significant percentage of this population oral therapy will fail, either because it simply does not work for them or because they have intolerable side effects. Being members of the action-oriented “baby boom” generation and now aware of the higher efficacies of other treatments (eg, a prosthesis), they will more likely seek these other forms of treatment. In addition, men who had “held out” for long intervals before evaluation will conceivably have more severe disease. Implants will likely be an option in this group of men with severe ED, especially if they have other medical conditions seen in our older population, such as diabetes, neuropathy, or athero-sclerosis.
With an increasing population, a growing public awareness of ED and the availability of effective treatments, and more general practitioners comfortably prescribing oral ED agents, we anticipate an increasing number of penile prosthesis procedures in the coming years. This speculation is supported by a recent Dain Bos-worth industry analysis report(n12) projecting an increase in the number of penile implant procedures performed through 2010.
CONCLUSIONS
Despite the advent of new oral medications to alleviate ED, the number of penile prosthesis procedures done for the treatment of ED will remain stable or increase. This will result from both an increased awareness and availability of different ED therapies and an increasing number of aging patients who have ED but do not respond to oral therapies. Ostensibly, there will always be a portion of the impotent population with advanced ED who will be candidates for penile prosthesis implantation. While the demand for such surgery will be maintained, a concern is that there are a decreasing number of urologists trained in penile prosthesis surgery. Also, a possible reduction in health insurance coverage for this medical condition in our cost-containing economic environment may signal a major health issue for the population with severe ED. Such concerns require further investigation.
TABLE. Distribution of Penile Prosthesis Implants, 1990 Through 1999
Legend for Chart:
A - Procedure
B - No. Procedures (%) 1990
C - No. Procedures (%) 1991
D - No. Procedures (%) 1992
E - No. Procedures (%) 1993
F - No. Procedures (%) 1994
G - No. Procedures (%) 1995
H - No. Procedures (%) 1996
I - No. Procedures (%) 1997
J - No. Procedures (%) 1998
K - No. Procedures (%) 1999
A B C D E
F G H
I J K
Total implants 54 63 56 37
54 70 70
53 54 50
Removal 2 (3.7) 8 (12.6) 4 (7.1) 5 (13.5)
4 (7.4) 4 (5.7) 10 (14.3)
8 (15.1) 9 (16.6) 6 (12.0)
Replacement 5 (9.2) 6 (9.5) 8 (14.2) 5 (13.5)
10 (18.5) 4 (5.7) 1 (1.4)
1 (1.8) 6 (11.1) 9 (18.0)
Revision 0 2 (3.1) 4 (7.1) 2 (5.4)
4 (7.4) 2 (2.8) 1 (1.4)
9 (16.9) 6 (11.1) 5 (10.0)
Simple/virgin 47 (87.0) 47 (74.6) 40 (71.4) 25 (67.6)
33 (66.6) 60 (85.7) 58 (82.8)
35 (66.0) 33 (61.1) 30 (60.0)
Procedure Type
Bar graph representing number of prosthesis cases
before and after introduction of sildenafil in 1998.
References
(n1.)
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(n2.)
Feldman HA, Goldstein I, Hatzichristou DG, et al: impotence and its medical and psychosocial correlates: results of the Massachusetts male aging study. J Urol 1994; 151:54-61
(n3.)
Mulcahy JJ: The role of penile prostheses. American Urological Association News. July/August 1999, p 16
(n4.)
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(n5.)
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(n7.)
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(n8.)
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(n9.)
Steers WD, Sildenafil Study Group: Meta-analysis of the efficacy of sildenafil (Viagra) in the treatment of severe erec-tile dysfunction. J Urol 1998; 159:239A
(n10.)
Slag MF, Morley JE, Elson MK, et al: impotence in medical clinic outpatients. JAMA 1983; 249:1736-1740
(n11.)
Shabsigh R: impotence on the rise as a urological subspecialty (Editorial). J Urol 1996; 155:924-925
(n12.)
Overview of the urology market. Dain Bosworth Industry Study.
From the Department of Urology, Tulane University School of Medicine, New Orleans, La.
Reprint requests to Wayne J. G. Hellstrom, MD, Tulane University School of Medicine, Section of Andrology and Male Sexual Dysfunction, Department of Urology, 1430 Tulane Ave SL42, New Orleans, LA 70112.
~~~~~~~~
By Grant E. Stanley, MD; Trinity J. Bivalacqua, BS and Wayne J. G. Hellstrom, MD, New Orleans, La
Adapted by MD , BS and MD
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Source: Southern Medical Journal, Dec2000, Vol. 93 Issue 12, p1153, 4p
