Impact of sling at time of prolapse surgery on overactive bladder

Abstract

Importance

Prolapse surgery and sling surgery both lead to improvement in overactive bladder. However, less is known regarding how slings performed concurrently with prolapse surgery impact overactive bladder.

Objectives

The primary aim was to compare change in post-operative overactive bladder symptoms in patients with pre-operative overactive bladder who underwent sling vs no sling with prolapse surgery.

Study Design

This is a secondary analysis of a cohort study evaluating overactive bladder in patients undergoing prolapse surgery. Slings were performed concomitantly for treatment or prevention of stress incontinence. Baseline and 3-month follow up urinary symptoms were assessed with the Overactive Bladder Questionnaire Short Form (OAB-q SF) and Urinary Distress Inventory-6 (UDI-6).

Results

Of patients with overactive bladder, 26 (40.0%) underwent midurethral sling and 39 (60.0%) no sling. Pre-operative OAB-q SF bother (score (SD), 46.8(20.2) vs 40.2(22.1), p=0.23) was similar between groups, but UDI-6 scores (59.2(28.8) vs 43.8(29.1), p=0.04) were higher in the sling group. At 3 months, the change (improvement) in OABq-SF bother (−16.9(24.1) vs −22.4(23.0), p=0.36), OABq-SF HRQOL (22.8(28.6) vs 22.9(23.9), p=0.99) and UDI-6 (−38.8(32.9) vs −34.0(27.8), p=0.53) were similar in MUS and no MUS groups.

Conclusions

Patients with prolapse and overactive bladder undergoing prolapse surgery with a sling had similar improvements in OAB-q SF bother scores compared to those who did not have a sling.

Introduction

Overactive bladder (OAB) is defined as, “urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence in the absence of urinary tract infection or other obvious pathology”.¹ OAB affects approximately 17% of women in the United States with an increasing prevalence with age.² Women with pelvic organ prolapse (POP) have an increased prevalence of OAB with rates varying up to 88%,³ and OAB symptoms have been shown to improve following POP treatment. In a study by Frigerio et al,⁴ 36.1% of patients undergoing surgery for POP had OAB symptoms which improved to 14.1% following surgery. Similarly, women with POP may also have either symptomatic or occult stress urinary incontinence (SUI) and may choose to undergo a concomitant midurethral sling (MUS) procedure with POP surgery for treatment of SUI. Women undergoing isolated MUS procedures are also known to have improvements in OAB symptoms.⁵

The objective of this study was to determine the impact of a MUS on OAB symptoms at the time of POP surgery. Given that women undergoing MUS surgery without POP repair experience improvement in OAB symptoms, we hypothesized that patients undergoing POP surgery with a MUS will have improved post-operative OAB symptoms compared to those without a MUS. Therefore, our primary aim was to compare change in post-operative OAB symptoms with the Overactive Bladder Questionnaire Short Form (OAB-q SF) in patients with baseline OAB who underwent MUS vs no MUS at time of POP surgery. Secondary aims were to (1) compare change in post-operative OAB symptoms with the OAB-q SF in patients with baseline OAB and SUI who underwent MUS vs no MUS at time of POP surgery and (2) compare post-operative Urinary Distress Inventory-6 (UDI-6) in patients with baseline OAB who undergo MUS vs no MUS at time of POP surgery.

Materials and Methods

Study design and participants

This is a secondary analysis of a prospective cohort study that evaluated OAB symptoms in patients with POP undergoing prolapse surgery (uterosacral ligament suspension (USLS), sacrospinous ligament fixation (SSLF), conventional or robotic-assisted laparoscopic sacral colpopexy (LSC), colpocleisis, and/or anterior vaginal repair).⁶ Participants in the parent study included women (age ≥ 18 years) with anterior and/or apical POP beyond the level of the hymen as defined by pelvic organ prolapse quantification (POP-Q) points Ba or C greater than 0. Exclusion criteria included evidence of urinary tract infection (UTI) at enrollment, non-evaluated microscopic hematuria, interstitial cystitis/bladder pain syndrome, nephrolithiasis, severe renal impairment (creatinine > 1.5), urinary retention (postvoid residual (PVR) > 150 ml), chronic antibiotic use, chronic steroid use, osteoporosis, urethral stricture disease, genital fistula, congenital urinary tract abnormality, active cancer, neurologic disease (spinal cord injury, multiple sclerosis, Parkinson disease, dementia, seizures, hemiplegia or stroke with residual deficits), pregnancy within 3 months, prisoners, and non-English speaking patients. Of note, the original study included patients with OAB and without OAB. This analysis only includes patients with baseline OAB.

Patients were enrolled and followed between July 2020 and January 2022. MUS was offered to patients as a concomitant procedure with POP surgery for treatment of co-existing SUI or for prevention of de novo SUI after discussion between the patient and surgeon. Regarding de novo SUI, our typical practice is to offer patients with occult SUI as demonstrated on pre-operative prolapse-reduction stress test a MUS with their POP surgery. Prolapse-reduction stress test is completed during pre-operative urodynamics with 2 large cotton-tipped swabs. Pre-operative urodynamics are not obtained if the patient has no desire to include a concomitant MUS with her POP surgery.

The University of Iowa Institutional Review Board (IRB) determined this secondary study was exempt from review because deidentified data was used. The primary study was approved by the IRB, and all participants signed informed consent documents. Research reported in the original publication that this study is based on was supported by the National Center For Advancing Translational Sciences of the National Institutes of Health under Award Number UL1TR002537.

Data Collection

Data collected via chart abstraction included age, parity, body mass index, medical comorbidities, surgical history, current medications, vaginal estrogen use, history of any OAB treatment, POP-Q measurements, urodynamic study results, post-void residual and history of POP treatment. Intraoperative procedures were also recorded. A urinalysis and urine culture were performed at the preoperative appointment to rule out UTI and hematuria.

Baseline and 3-month follow up urinary symptoms were assessed with the OAB-q SF and Pelvic Floor Distress Inventory Short Form-20 (PFDI-20).^{7, 8} The OAB-q SF is a 19-item validated survey composed of a 6-item OAB specific symptom bother scale and a 13-item health related quality of life (HRQOL) scale. Study participants were categorized as OAB or no OAB pre-operatively based on answering ‘sometimes’ or greater on question 1, 2, 5, or 6 of the OAB-q SF bother scale. The OAB-q SF score was used to assess the primary aim. Responses consist of a 6-point Likert scale for symptom bother and HRQOL over the past 4 weeks. Higher scores indicate more bother from OAB symptoms (Bother subscale) or better QOL (less OAB impact; HRQOL scale). The PFDI-20 is a 20-item validated survey that evaluates the effects of pelvic floor disorders on health-related quality of life. The questionnaire consists of three scales including a 6-item POP distress inventory, 8-item colorectal-anal distress inventory, and a 6-item urinary distress inventory (UDI-6) with a 4-point Likert scale for symptom bother over the last 3 months. Symptomatic SUI was defined as a positive response to question #3 of the UDI-6.

Data Analysis

Demographics, medical history, and surgical variables were compared between groups as appropriate with t-test, chi squared and Wilcoxon rank sum tests. Categorical variables are represented as frequencies and percentages, while normally and non-normally distributed continuous measures are represented as mean (standard deviation) and median (interquartile range), respectively.

For the primary and secondary aims, post-operative questionnaire scores were compared between groups (MUS vs no MUS) using t-test.

Power Calculation

The study sample size was dependent on the sample size of the parent study. However, a prior study comparing antimuscarinic and beta-3 agonist treatment for OAB found an approximately 30-point improvement in transformed OAB q-SF bother score with treatment.⁹ Based on this, a post hoc power analysis indicated that 13 patients are needed in each group to provide 80% power at alpha 0.05 to demonstrate a similar difference in OAB symptoms between groups.

Results

A total of 85 patients enrolled in the study. Eight patients were either excluded after enrollment due to identification of exclusion criteria or voluntarily withdrew. For this analysis, an additional 10 patients without baseline OAB were excluded, and 2 patients were excluded due to missing post-operative OAB-q answers. Twenty-six (40.0%) patients underwent MUS and 39 (60.0%) no MUS. The MUS and no MUS groups were similar in most baseline characteristics, including age (61.7 vs 65.5 y, p=0.14) and body mass index (29.8 vs 27.9 kg/m², p=0.11) (Table 1). Baseline (symptomatic) SUI was more common in the MUS group (22(84.6%) vs 13(33.3%), p<0.01) (Table 2). Pre-operative urodynamics with prolapse reduction stress testing was available for 51 patients. Stress testing was positive in 22 of 26 (84.6%) in the MUS group and 7 of 25 (28%) in the no MUS group (p<0.01). Pre-operative OAB-q SF bother (score (SD), 46.8(20.2) vs 40.2(22.1), p=0.23) was similar between groups, but UDI-6 scores (59.2(28.8) vs 43.8(29.1), p=0.04) were higher in the MUS group (Table 2).

Table 1.

Baseline demographics, clinical characteristics and surgical data. All data reported as n(%) unless otherwise stated. MUS = mid-urethral sling; y = years; SD = standard deviation; kg = kilogram; m = meters; SUI = stress urination incontinence; POP = pelvic organ prolapse; OAB = overactive bladder; IQR = inter-quartile range; PVR = post-void residual; mL = milliliter.

	MUS (n=26)	No MUS (n=39)	p
Age (y, SD)	61.7 (10.9)	65.5 (9.4)	0.14
BMI (kg/m2, SD)	29.8 (4.4)	27.9 (4.4)	0.11
Race			0.42
White	25 (96.2)	37 (94.9)
Black	1 (3.8)	0
Hispanic	0	1 (2.6)
Asian	0	1 (2.6)
Tobacco use	5 (19.2)	7 (17.9)	0.90
Hypertension	13 (50.0)	23 (59.0)	0.48
Hyperlipidemia	10 (38.5)	16 (41.0)	0.84
Prior hysterectomy	4 (15.4)	13 (33.3)	0.11
Prior POP surgery	3 (11.5)	6 (15.4)	0.66
Prior SUI surgery	1 (3.8)	3 (7.7)	0.53
Vaginal estrogen use	7 (26.9)	14 (35.9)	0.45
Current OAB treatment	1 (3.8)	2 (5.1)	0.81
POP-Q stage (IQR)	3 (2-3)	3 (2-3)	0.08
PVR (mL, SD)	22.1 (32.0)	42.7 (43.1)	0.04
Hysterectomy	18 (69.2)	25 (64.1)	0.67
Vaginal native-tissue POP surgery	13 (50.0)	26 (66.7)	0.18
Sacrocolpopexy	11 (42.3)	10 (25.6)	0.16
Colpocleisis	2 (7.7)	3 (7.7)	1.00

Table 2.

Main results. All data reported as score (SD) unless stated otherwise. MUS = mid-urethral sling; OABq SF = Overactive Bladder Questionnaire Short Form; HRQOL = health-related quality of life; UDI-6 = Urinary Distress Inventory-6; SUI = stress urinary incontinence; PFDI-20 = Pelvic Floor Distress Inventory-20. *SUI defined as a positive response to question #3 of the UDI-6. ^Total n for the UDI-6/PFDI-20 comparisons was 25 in the MUS group and 38 in the no MUS group due to missing responses.

	MUS (n=26)	No MUS (n=39)	p
Pre-op
OABq SF Bother	46.8 (20.2)	40.2 (22.1)	0.23
OABq SF HRQOL	59.2 (23.3)	69.1 (24.7)	0.11
UDI-6	59.2 (28.8)	43.8 (29.1)	0.04
SUI (n (%))*	22 (84.6)	13 (33.3)	<0.01
PFDI-20	137.8 (73.9)	115.0 (64.0)	0.20
Post-op
OABq SF Bother	29.9 (22.4)	17.8 (16.6)	0.02
OABq SF HRQOL	82.0 (20.1)	92.0 (11.9)	0.01
UDI-6^°	20.3 (22.3)	9.8 (11.7)	0.02
SUI (n (%))*^	6 (23.1)	11 (28.2)	0.67
PFDI-20^	42.9 (36.6)	22.9 (27.2)	0.02
Pre-op to Post-op Change
OABq SF Bother	−16.9 (24.1)	−22.4 (23.0)	0.36
OABq SF HRQOL	22.8 (28.6)	22.9 (23.9)	0.99
UDI-6^	−38.8 (32.9)	−34.0 (27.8)	0.53
PFDI-20^	−94.9 (78.5)	−92.1 (56.1)	0.87
Pre-op to Post-op Change (limited to patients with baseline OAB AND SUI)
OABq SF Bother	−18.1 (25.3)	−22.1 (24.2)	0.66
OABq SF HRQOL	24.5 (29.9)	26.0 (28.9)	0.89
UDI-6^	−44.8 (28.4)	−48.3 (29.8)	0.75
PFDI-20^	−110.0 (67.9)	−98.5 (57.3)	0.63

At 3 months after surgery, the change (improvement) in OABq-SF bother (−16.9(24.1) vs −22.4(23.0), p=0.36), OABq-SF HRQOL (22.8(28.6) vs 22.9(23.9), p=0.99) and UDI-6 (−38.8(32.9) vs −34.0(27.8), p=0.53) were similar in MUS and no MUS groups. Results were similar when limiting the analysis to patients with both OAB and symptomatic SUI at baseline (Table 2). Compared to those who had POP surgery without MUS the MUS group had higher OABq-SF bother (29.9(22.4) vs 17.8(16.6), p=0.02), lower (worse) OAB-related HRQOL (82.0(20.1) vs 92.0(11.9), p=0.01), and higher (worse) UDI-6 scores (20.3(22.3) vs 9.8(11.7), p=0.02). Notably, there was no difference in SUI based on the UDI-6 between groups post-operatively (6(23.1%) vs 11(28.2%), p=0.67).

Discussion

Contrary to our hypothesis, patients with POP and OAB undergoing POP surgery with a MUS and without a MUS had similar improvement in post-op OAB-q SF bother scores.

Patients in both groups (MUS and no MUS) experienced reductions in OAB-qSF bother and UDI-6 scores. This is consistent with prior studies demonstrating improvements in OAB symptoms with POP treatment.^{3, 4} MUS surgery, in the absence of concurrent POP surgery, has also previously been found to improve OAB symptoms in a majority of patients but also cause de novo OAB in about 9% of patients.^{5, 10} Less research has focused on the change in OAB symptoms in women with OAB undergoing POP surgery with or without a MUS. One study evaluating risk factors for post-operative OAB in 518 women undergoing POP surgery found MUS to be an independent risk factor for OAB after surgery.⁴ Alternatively, Johnson et al¹¹ found no significant difference in the rate of OAB resolution after POP surgery in MUS vs no MUS groups.

The primary strengths of this study include the prospective design of the parent study and use of validated questionnaires. All participants were recruited from one site with similar practices amongst surgeons. Limitations of the study include the relatively low number of patients when divided into MUS and no MUS groups. A heterogeneous group of POP surgeries were also included. The risk of persistent OAB may be dependent on the type of POP surgery performed. However, we were not powered to explore this question. Additionally, this study has the significant limitations of any non-randomized study. Specifically, there is likely to be selection bias in the MUS and no MUS groups. Also, women who knew they received a MUS may answer follow up questions regarding bladder symptoms differently than those who elected not to receive a MUS. Further research is needed to better define differences between these two groups. Our results are likely to be generalizable to urogynecology practices that counsel patients similarly regarding a recommendation for a concurrent sling with prolapse surgery. We also acknowledge that our patient population is predominantly White, and our results may be less generalizable to other populations.

Future research should also focus on the differences in OAB symptoms in patients having POP surgery with and without MUS. To date, most research in this population has focused on either SUI symptoms or overall LUTS. While there is now abundant data that OAB symptoms improve in many women having isolated POP surgery and isolated SUI surgery, this study suggests that POP surgery with concurrent SUI surgery may not lead to better post-operative OAB symptoms than POP surgery alone.

In conclusion, we found that patients with POP and OAB undergoing POP surgery with a concurrent MUS had similar improvements in OAB compared to those who did not have a concurrent MUS with POP surgery.

Simply Stated.

Patients with overactive bladder symptoms who have surgery for pelvic organ prolapse may or may not also have a sling surgery for treatment of stress incontinence at the same time as fixing the prolapse. The impact that sling surgery has on overactive bladder symptoms at the time of prolapse surgery is not well understood. Therefore, our objective was to compare post-operative overactive bladder symptoms in patients with pre-existing overactive bladder who had surgery for prolapse with or without a concurrent sling. Although we hypothesized that women with a sling would experience more improvement in overactive bladder than those without a sling, we found that patients who had a sling had similar improvements in overactive bladder compared to those without a sling.

Why This Matters?

• Patients undergoing either prolapse surgery or midurethral sling surgery are known to often have improvement in overactive bladder.

• However, the impact of a sling concurrently with prolapse surgery on overactive bladder symptoms is not well understood.

• We compared post-operative overactive bladder symptoms in patients with pre-existing overactive bladder undergoing prolapse surgery with or without a concurrent sling.

• Patients with and without slings experienced similar improvements in overactive bladder symptoms.

• This information may be used to better counsel patients with overactive bladder who are considering a sling with their upcoming prolapse surgery.