Trends and Clinical Practice Patterns of Sacral Neuromodulation For Overactive Bladder

Abstract

Objectives

To investigate surgical practice patterns of American urologists treating refractory OAB over the last decade. Refractory overactive bladder (OAB) remains a management challenge to urologists. When multiple medical therapies have failed, treatment options may include sacral neuromodulation (SNM) or surgery such as augmentation cystoplasty (AC).

Methods

Data on SNM and AC performed between 2003 and 2012 by certifying and recertifying urologists were obtained in the form of annualized case logs from the American Board of Urology (ABU). Associations between surgeon characteristics (type of certification, annual volume, practice type and location) and these procedures were evaluated.

Results

Over the past decade 756 of 6,355 urologists certified with the ABU performed SNM or AC for the treatment of refractory OAB. 45 of these surgeons (6%) completed fellowships in female urology and 72 surgeons (10%) completed another type of fellowship program. Surgeons recertifying with ABU performed 70% of all SNM procedures. While SNM and AC have increased from 64 to 2086 between 2003–2012, however this is mainly driven by the increase of SNM from 48 to 2068 cases. Rates of AC have remained stable with 14 to 38 cases reported annually. However, they have declined relative to the total, from 25% in 2003 to <1% in 2012.

Conclusions

SNM has increased dramatically over the last decade in surgeons certified with the ABU. This is in contrast to AC, which while remaining stable in number of procedures.

Manuscript Summary:

In comparison to AC, SNM has increased over the last decade amongst surgeons certified with ABU.

Introduction

Overactive bladder (OAB) is defined by the International Continence Society as urinary urgency, with or without urinary incontinence, usually with frequency and nocturia.¹ Approximately 16.5% or 34 million people suffer from OAB in the United States.² Initial treatment of OAB includes changes in behavior, i.e. decreased fluid intake, timed voiding, and pelvic floor muscle exercises. If there is not adequate improvement of symptoms with behavioral therapy alone, the next line of treatment is pharmacological, including anticholinergic medications,³ which primarily have side effects of dry mouth and constipation, or beta-3 agonists⁴ promising new agents with little long-term data. If OAB is non-responsive to these drugs, more invasive therapy is necessary for treatment.

Management of OAB refractory to these medications represents a therapeutic challenge. The 2012 American Urological Association (AUA) guidelines recommend either sacral neuromodulation (SNM) or peripheral tibial nerve stimulation as an approved third line agent as well as intradetrusor injection of onabotulinumtoxin A. If these measures fail, these patients are recommended to undergo augmentation cystoplasty (AC), neobladder construction, or urinary diversion.⁵ In adults, however, urinary diversions (including neobladder creation) are rarely done for OAB. They are commonly used as reconstruction after radical cystectomy.

Our objective was to analyze the surgical practice patterns of American urologists performing AC or SNM for refractory OAB over the last 10 years. We used annual case logs submitted to the American Board of Urology (ABU) for certification and re-certification between the years 2003–2012 for this analysis.

Methods

Data was obtained from the case logs of urologists applying for certification or recertification by the ABU between 2003 and 2012. The only data included in this study were de- identified data requested from the ABU. Since the data were de-identified and no institutional data from Memorial Sloan Kettering Cancer Center (MSKCC) were used for this study, this study did not require Institutional Review Board (IRB) approval at our institution. Applicants provided six months of billing data as a case log. Case logs for 6 months were annualized for this study. These case logs are submitted for original certification and for recertification every ten years thereafter. As has been reported in previous studies, this data represents 100% of urologist seeking board certification or maintenance of certification, which is approximately 10% of all certified urologists.^6,7 Data was available on surgeon sex, age, location, practice area, specialty or subspecialty, fellowship training, year of original certification, whether the surgeon was applying for certification or recertification, current procedural terminology (CPT) codes and number of patients in each decade of age who had the procedure for each CPT code. Urologists were excluded from analysis if they self-reported a pediatric subspecialty since pediatric procedures are etiologically different than adult procedures, particularly as related to AC. Surgeons were not excluded if they performed procedures on patients younger than 19; however, these cases were excluded from analysis.

We hypothesized that the total number of SNM and AC would increase between 2003 and 2012, and that SNM would gradually replace AC as the primary surgical treatment for refractory OAB. We also hypothesized that younger surgeons would be more likely to perform SNM procedures than older surgeons. We posited that fellowship-trained urologists, and specifically those trained in a female urology fellowships, would perform more SNM or AC than non-fellowship-trained physicians. Linear regression was used to determine whether fellowship training, age or certification status was predictive of a surgeon’s case volume for both SNM and AC. Logistic regression was used to assess associations between different surgeon characteristics. All analyses were performed using Stata 12 (StataCorp, College Station, TX).

Results

Out of 6,355 urologists applying for ABU certification, only 756 reported any use of SNM or AC during the 6-month period recorded by the case logs. Among urologists in this group, 230 were applying for original certification and 526 were applying for recertification. The median ages at original certification and first, second and third recertification were 34 years, 42 years, 52 years and 60 years, respectively. The volume of SNM or AC performed annually was relatively low. In 2003, only 64 procedures were reported. The number of these procedures performed annually has increased steadily over the last decade to 2,086 procedures in 2012.

The two codes for SNM (CPT codes 64561 and 64581) were most commonly reported among this group. Forty-eight SNM procedures for OAB were reported in 2003. As seen in Figure 1, the use of SNM has increased steadily, with ABU applicants reporting 2,068 of these procedures in 2012. AC (CPT 51960) was much less common (Table 2). Use of AC peaked in 2004 with 38 reported cases. Only 18 AC cases were reported in 2012.

Figure 1.

Use of Procedures to Treat Overactive Bladder Between 2003 and 2012. Solid line: Sacral Neuromodulation. Enterocystoplasty was not included on this graph due to the low number of cases annually.

Table 2.

Rates of AC procedure and number of SNM procedures performed by certification exam number

	Performed any AC procedures1	SNM procedures2
Certification (N=230)	23 (10%)	4 (2, 12)
First Recertification (N=355)	34 (10%)	6 (2, 16)
Second Recertification or more (N=165)	19 (11%)	6 (2, 18)

¹reported as percentages

²reported as interquartile ranges

While we originally hypothesized that younger, originally-certifying surgeons would be more likely to use SNM procedures, we found that the opposite was true (Table 3). On average, recertifying surgeons performed 12.4 SNM procedures per year, while originally certifying surgeons performed an average of 9 of these procedures annually (difference between means 3.4; 95% CI 1.1, 5.7; p = 0.004). We also found that age was associated with a higher volume of SNM procedures, and urologists reported about 1.1 more SNM case for every five years of age (95% CI 0.4, 1.9; p = 0.003). While the majority of applicants reported no fellowship training, some urologists reported training in either a female urology fellowship or any other type of urology fellowship. Forty-six urologists (6%) had completed a female urology fellowship, while an additional 71 (9%) completed non-female urology fellowship training (Table 2). About 15 percent of certifying urologists reported training in any urology fellowship. Among urologists with fellowship training who treated refractory OAB, 18% performed any AC procedures and 91% performed any SNM procedures, as compared to 8.6% and 94% of non-fellowship-trained urologists treating refractory OAB, respectively. Forty percent of fellowship-trained urologists who treated OAB reported fellowship training in female urology, and male urologists were less likely to have completed fellowships in female urology than their female colleagues (OR 2.4 for females; 95% CI 1.1, 5.5; p = 0.037). However, female-urology specialists did not perform more AC or SNM procedures annually than their colleagues who had completed other urology fellowships (difference in means 1.3; 95% CI −3.2, 5.9; p = 0.6). Rates of SNM and AC use were 98% and 11% among female-urology specialists, respectively, as compared to rates of 87% and 23% among urologists with other fellowship training.

Discussion

OAB represents a therapeutic challenge that many urologists face. Over the past decade, urologists have adopted novel approaches to deal with refractory OAB. Using the data from case logs of certifying and recertifying urologists, we are able to elucidate trends in practice patterns from this sample of urologists in the United States over the past decade. SNM use has seen increased utilization since it was first approved for use in 1997 by the Food and Drug Administration.⁸ SNM cases increased from 48 cases in 2003 to over 2000 cases in 2012. This is in part a reflection of the change in the device in 2002, when the procedure was made less invasive with the introduction of tined leads that decreased the need for open implantation and suturing to the presacral fascia.⁹ Currently, close to 80% of all SNM cases are performed for OAB, with the remainder placed for retention and off-label uses.⁸

Notably, older and recertifying urologists performed more procedures than those certifying for the first time, possibly due to recertifying urologists having a larger number of patients with refractory OAB. Alternatively, recertifying urologists might be more likely to move beyond medical therapy, whereas certifying urologists might cycle through the multiple available drugs prior to classifying a patient as “refractory.” We also found overall only 11.8% of urologists applying for ABU certification or re-certification reported the use of AC or SNM for refractory OAB. It is interesting to note that the number of AC remained relatively stable throughout the decade, representing a reasonably stable number of patients suffering from refractory OAB. These numbers likely represent those that failed third line therapy such as Botox and SNM.

There have been a few analyses on SNM using Medicare data. Specifically, Cameron and colleagues reported on trends and utilization of SNM in the 5% sample of Medicare beneficiaries (1997 to 2007) and from employees of 25 large companies from 2002 to 2007.¹⁰ In this time period a total of 1132 SNM procedures were done in the Medicare sample and 794 in the private sector. Of these in the Medicare group 435 were for wet OAB and 233 for dry OAB. In the private sector, 323 were for wet OAB and 25 in the dry OAB group. The authors did not discuss the change in utilization of these procedures over time; they mainly discussed predictors of success in SNM placement. The authors later used the same data to find that there were 561 total implants placed between 1997 and 2007. Of those implants placed, 63 were removed in a mean of 60.5 months. Overall, only 10.3 percent of SNM implants were removed in this period of time.¹¹

This study has several strengths, including the fact that this is a contemporary analysis of recent urologist practice across all geographic locations and practice types in the United States. The data used in this analysis also encompass approximately 10 percent of all board-certified urologists each year and gives information on applicant characteristics. Several other publications have used this approach to report on other procedures and practice patterns in other arenas of urinary dysfunction.^6,7 However, there were several limitations to this study: it lacks information on case mix, as data is collected as count data by CPT code with no patient information included. We did not specifically evaluate SNM revisions. CPT codes for onabotulinum toxin A injection were not available for this time period and therefore could not be evaluated. When looking at the SNM and AC, the rates of AC may be of those patients who were more likely to fail SNM. Furthermore, SNM was a procedure commonly performed by urogynecologist during the time period., which was not captured, thus these findings are limited to urologists.

Conclusion

OAB is increasingly prevalent in the aging population and urologists now have more modes of treatment available. In the past decade, improvements in the SNM device and more urologists trained in the technique have led to a greater than thirty-fold increase in its utilization. The number of third-line salvage AC has remained stable over time. Despite this, very few urologists have performed SNM even amongst those who have been fellowship trained. This may represent a disparity in third line agents or patient/surgeon reluctance in SNM. This will need further exploration to ensure SNM has appropriate adoption for those suffering from refractory OAB.

Table 1.

Characteristics of Urologists Who Reported Performing Overactive Bladder Procedures (n=756). Data is reported as median (interquartile range) or count (percentage).

Male Gender	634 (84%)
Surgeon Age	42 (36, 48)
Fellowship Training
Female Urology	46 (6%)
Any Non-Female Urology	71 (9%)
No Fellowship	639 (85%)
Number of OAB Procedures by Surgeon	6 (2, 14)
Specialty
Female	196 (26%)
General	398 (53%)
Other	24 (3%)
Unknown	138 (18%)
Size of Practice Area
< 100,000	106 (18%)
100,000 – <=250,000	102 (17%)
250,001 – <=500,000	90 (15%)
500,001 – <=1,000,000	94 (16%)
1,000,000+	211 (35%)