Success of Concomitant Versus Interval Slings for Prevention and Treatment of Bothersome de Novo Stress Urinary Incontinence

Abstract

Background:

Despite large trials designed to guide management on whether to perform a prophylactic continence procedure at the time of pelvic organ prolapse (POP) repair, it remains unclear if a staged or interval approach confers advantages in treatment of bothersome stress urinary incontinence (SUI) in women without bothersome SUI before their POP repair.

Objective:

The objective of this study was to compare success of concomitant versus interval slings for the prevention/treatment of de novo bothersome SUI after POP repair.

Study Design:

This multicenter retrospective cohort with prospective follow-up enrolled women with minimal or no SUI symptoms who underwent minimally invasive apical surgery for stage 2 or higher POP between 2011 and 2018 and had a concomitant sling placed at the time of POP surgery or an interval sling placed. Prospectively, all patients were administered the Urogenital Distress Inventory Short-Form 6, the Patient Global Impression of Improvement, and questions on reoperation/retreatment and complications.

Results:

A total of 120 patients had concomitant slings, and 60 had interval slings. There were no differences in the proportion of patients who had intrinsic sphincter deficiency (22% vs 20%), although the concomitant sling group was more likely to have a positive cough stress test result (30% vs 8%, P = 0.006). The interval sling group was more likely to report “yes” to SUI symptoms on Urogenital Distress Inventory Short-Form 6 (3% vs 30%, P = 0.0006) and during their postoperative visit (0% vs 24%, P < 0.0001). There were no differences in surgical complications.

Conclusions:

Among women with minimal or no SUI symptoms undergoing prolapse repair, concomitant slings resulted in lower rates of bothersome SUI compared with similar women undergoing interval sling placement.

Despite large trials designed to guide management on whether to perform a prophylactic continence procedure at the time of pelvic organ prolapse (POP) repair, it remains unclear whether a staged or interval approach confers advantages in treatment of bothersome stress urinary incontinence (SUI) in women without bothersome stress incontinence symptoms before their POP repair. Little is known regarding the cure rate of interval slings for women with bothersome de novo SUI after prolapse repairs, although recent retrospective studies have shown that, among women with demonstrable SUI who are treated with a staged approach, one third of the incontinence will resolve postoperatively, but half will pursue further treatment for SUI with 37% ultimately having a midurethral sling (MUS) procedure.¹ The outcomes of how these MUS procedures performed with regard to SUI symptoms were not reported. Data are also lacking regarding whether there is a difference in outcomes based on a preoperative positive or negative cough stress test (CST) result. In the largest trial available to guide management on this topic, the Outcomes Following Vaginal Prolapse Repair Midurethral Sling (OPUS) trial, women without SUI before prolapse surgery were randomized to receive a MUS at the time of their POP repair versus POP repair alone. Postoperatively, regardless of CST results, patients who had not received a sling had a 49% rate of SUI at 3 months and 43% at 12 months.² It remains unclear if the 8 women (4.7%) in the sham arm of the OPUS trial who underwent a staged MUS had differing objective or subjective success compared with women with a prophylactic sling placed at the time of their POP surgery because this study was not powered to address interval sling efficacy.

Of note, asymptomatic women who undergo a concomitant sling procedure at the time of POP repair have at least a 17% risk of developing postoperative SUI, which is comparable with known cure rates of MUS alone.³ Studies done in women with symptomatic preoperative SUI showed success rates and complication rates that were not significantly different for concomitant versus interval slings.⁴ Specifically, we are not aware of any data evaluating the success of interval MUS for the treatment of de novo bothersome SUI that develops after POP repair. We are interested in determining if an interval sling has better success compared with concomitant sling in this population of women with minimal or no preoperative SUI symptoms.

MATERIALS AND METHODS

This is a multicenter Fellows Pelvic Research Network retrospective cohort study⁵ with prospective follow-up of a subgroup of patients from 7 academic Female Pelvic Medicine and Reconstructive Surgery divisions. Institutional review board approval was obtained to conduct the chart review and to contact patients for follow-up questionnaires. The target study population was patients with minimal to no SUI symptoms preoperatively who underwent minimally invasive (vaginal, laparoscopic, or robotic), apical POP surgery for stage 2 or higher POP between January 1, 2011, and December 31, 2018. Women with minimal to no SUI were chosen to mirror the population of the OPUS trial.² Using Current Procedural Terminology codes, we identified patients who underwent POP surgery and concomitant sling placement and those who underwent POP surgery alone followed by interval sling placement during this period. Retropubic, transobturator, and rectus fascial slings were included in anticipation of a small cohort of interval slings. The index surgery was defined as the initial POP surgery, regardless of sling placement. All data were entered in REDCap.⁶ A retrospective chart review was performed for both the interval and concomitant sling groups to determine which women had minimal to no bothersome SUI symptoms before their index surgery. Eligible women had no symptoms of SUI or minimal symptoms of SUI on preoperative history either in the history of present illness, assessment, and plan or on validated measure Urogenital Distress Inventory Short-Form 6 (UDI-6). Patients with minimal SUI were included if they indicated “minimal,” “rare,” or “drops” and were not bothered by this because this could potentially change surgical decision making. We collected demographic data, including age, body mass index (BMI), race/ethnicity, menopausal status, smoking status, and prior surgery for SUI or POP. Data were also collected on POP stage using the Pelvic Organ Prolapse Quantification System (POP-Q)⁷ preoperatively and postoperatively, results of preoperative CST (reduced in office or as part of urodynamic studies [UDS]) if available, preoperative urodynamic parameters when performed, type of sling procedure performed, surgical complications, and subjective complaints of SUI and overactive bladder (OAB) preoperatively and postoperatively from the index prolapse procedure as reflected in the chart. Patients were enrolled chronologically, starting with patients who had most recently had surgery and working backwards in time.

Patients who were able to be reached prospectively were queried with the UDI-6⁸ and Patient Global Impression of Improvement (PGI-I),⁹ which are both validated for phone, written, and electronic forms. The UDI-6 is a 6-question assessment tool that is scored on a scale of 0 to 100, with higher scores indicating higher bother. The PGI-I is a 7-point Likert scale designed to assess preintervention and postintervention improvement ranging from very much better (1) to very much worse (7). An attempt was made to contact all patients who met the study inclusion and exclusion criteria from the 2 groups, with an exception made for sites that collect UDI-6 and PGI-I at adequate length of follow-up (≥6 weeks). Questions were also asked about complications related to their sling and any reoperations for SUI, POP, or complications. Patients who could not be contacted for prospective follow-up underwent a retrospective chart review only, and their most recent postoperative visit (at minimum ≥6 weeks) was queried for the presence or absence of postoperative SUI symptoms. All prospective data reported, including validated data from the UDI-6 and the PGI-I, reflect the current status of both groups of patients, all of whom have had a sling performed.

Patients were included if they were 18 years or older, underwent a minimally invasive apical support procedure (colpocleisis [57106, 57110, 57120]; vaginal colpopexy [57282, 57283]; laparoscopic surgical colpopexy [57425]; sling [57288], including retropubic, transobturator, and fascial sling) for POP-Q stage 2 or higher anterior/apical POP (Ba or C greater than or equal to 0), had no or minimal symptoms of SUI as defined, and were determined by their surgeon to be a candidate for a sling. Patients were excluded for moderate or severe SUI symptoms, open abdominal POP procedure, concomitant SUI surgery that was not a sling (Burch, injection of a bulking agent or other procedure, Kelly plication not excluded), history of a prior sling placement before index POP surgery, neurologic disorder, and preoperative incomplete bladder emptying that did not resolve with prolapse reduction (postvoid residual volume [PVR] >150 mL). Patients were included regardless of surgeon practice pattern. Concomitant and interval slings were distributed evenly between the participating sites without any 1 site contributing a disproportionate number of concomitant or interval slings.

For our primary aim, comparing success (improvement/prevention) of concomitant and interval MUS for prevention and treatment of de novo bothersome SUI, success was defined as a composite of both absence of SUI symptoms and lack of reoperation or additional nonsurgical treatment (ie, continence pessary) for SUI. Absence of symptoms was defined: prospectively by a response of “no” with a score of 0 or bother “not at all” with a score of 1 to UDI-6 question 3 (Do you experience urine leakage, and if so, how much are you bothered by it related to physical activity, coughing, or sneezing?) and retrospectively by answering “no” when asked about SUI symptoms during the postoperative visit. Conversely, failure was defined as a response of “yes” with a bother score of 2 or greater and if the patient had undergone reoperation or retreatment for SUI.

Secondary aims of this study compared urinary symptoms using the UDI-6, satisfaction using the PGI-I, and sling-related complications (voiding dysfunction, urinary retention, bladder perforation, mesh erosion, and sling revision) in women with concomitant and interval slings. We also determined if there were associations between available preoperative urodynamic findings such as detrusor overactivity (DO) and intrinsic sphincter deficiency (ISD) and postoperative urinary symptoms among the 2 groups.

Because of the low proportion of surgical procedures with interval sling, a sampling ratio of 2:1 was proposed and required a multicenter study. It was determined before initiating data collection that our study would reach 80% power by including 120 women in the concomitant sling group and 60 women in the interval sling group (2:1 ratio nonmatched) to detect a 15% difference between the study groups when assuming that the postoperative cure rate or prevention of SUI is 80% in the concomitant sling group and 95%¹⁰ in the delayed sling group, extrapolated from prior studies. Sample size calculation was conducted in Power Analysis and Sample Size using 2-sample proportions test algorithm at 2-sided α = 0.05.¹¹

STATISTICAL ANALYSIS

Continuous variables were summarized as means and SDs, and categorical variables were aggregated as frequencies and percentage. The t test/Wilcoxon rank sum test and 1-way analysis of variance/Kruskal-Wallis were performed to detect the difference of continuous variables between groups. The χ²/Fisher exact tests were used to compare categorical variables between groups. Correlation analysis was applied to assess association of 2 continuous variables; P values of ≤0.05 were considered to be significant. Odds ratios were calculated with 95% confidence intervals. Data collected prospectively were analyzed separately as a subjective adjunct to the retrospective chart data. Missing data were not included in the denominator of the analysis.

RESULTS

A total of 513 patients were screened for the study, 284 in the concomitant group and 229 in the interval group. Based on the exclusion criteria, we excluded 164 from the concomitant group and 169 from the interval group to enroll 180 patients in the study—120 in the concomitant sling group and 60 in the interval sling group (Fig. 1). All results are reported as concomitant group versus interval sling group, respectively. Of these, 61 patients (51%) in the concomitant sling group and 30 patients (50%) in the interval group were reachable for prospective surveys, and the remaining patients with only retrospective data available had SUI symptoms recorded via the most recent postoperative visit on record. Prospectively, follow-up was 171 ± 101.5 weeks versus 130 ± 65.6 weeks, and retrospectively, follow-up was 52.4 ± 54.7 weeks versus 38.3 ± 59.2 weeks. Patient demographics were not significantly different between groups, including age (68.7 vs 69.3 years, P = 0.8), BMI (32.6 vs 28.7 kg/m², P = 0.5), postmenopausal status (91.7% vs 88.3%, P = 0.4), or smoking status (2% vs 5%, P = 0.4) (Table 1). The interval sling group was more likely to have prior POP surgery (6.7% vs 21.7%, P = 0.003). Two patients in the concomitant group had a prior Burch, and 1 patient in the interval group had prior coaptite. The majority of patients in both groups had stage 3 POP before their index surgery (70% vs 68%); however, there was more severe (stage 4) POP in the concomitant group (23% vs 12%) and more mild (stage 2) POP in the interval group (7% vs 20%). The majority of patients in both groups underwent a minimally invasive sacrocolpopexy (62.5% vs 50%); however, there were more sacrocolpopexy and colpocleisis (16.6% vs 3.3%) procedures in the concomitant group and more vaginal native tissue (20.8% vs 38.3%) and vaginal mesh hysteropexy (0 vs 8.3%) procedures in the interval group (P = 0.002). Postoperatively, there were no differences in POP-Q stage between groups with the majority having stage 0 or 1 (66% vs 73%), but several had recurrent stage 3 or 4 POP (28% vs 19%), although there were no reoperations for POP in either group. The type of sling used was similar in each group with more than 90% retropubic mesh MUS, followed by 5–8% transobturator mesh MUS and 1–2% autologous fascial slings (1 in each group). Baseline minimal and not bothersome subjective SUI (40.0% vs 36.7% P = 0.7) did not differ between groups. After the index surgery was complete but before the interval slings were placed, there were more SUI symptoms in the interval group (8% vs 68%, P < 0.0001). For reference, on average, 33.6 ± 35.1 weeks elapsed between the index surgery and placement of the interval sling. The relative differences between prospective and retrospective length of follow-up seem to correlate roughly with the elapsed time between index surgery and interval sling.

FIGURE 1.

Study design. POP, pelvic organ prolapse; PVR, postvoid residual volume; SUI, stress urinary incontinence.

TABLE 1.

Baseline Characteristics

	Concomitant	Interval
	(n = 120)	(n = 60)	P
Age, y	68.7 (14.9)	69.3 (12.7)	0.8
BMI	32.6 (64.6)	28.7 (15.6)	0.5
Postmenopausal	110 (92.4%)	53 (88.3%)	0.4
Current smoker	3 (2.5%)	3 (5.1%)
Prior POP surgery	8 (6.7%)	13 (21.7%)	0.003
Prior SUI surgery	1 (0.8%)	2 (3.3%)	0.22
Retropubic mesh sling	110 (91.7%)	56 (93.3%)
Transobturator mesh sling	9 (7.5%)	3 (5.0%)	0.8
Fascial sling	1 (0.8%)	1 (1.7%)
Index POP surgery
Sacrocolpopexy	75 (62.5%)	30 (50%)
Vaginal native tissue repair (USLS, SSLS)	25 (20.8%)	23 (38.3%)	0.002
Colpocleisis	20 (16.6%)	2 (3.3%)
Mesh hysteropexy	0	5 (8.3%)
Preop POP-Q stage
Stage 2	8 (6.7%)	12 (20.3%)	0.01
Stage 3	84 (70.0%)	40 (67.8%)
Stage 4	28 (23.3%)	7 (11.9%)
Subjective SUI preop
Yes, minimal	48 (40.0%)	22 (36.7%)	0.7
No	72 (60.0%)	38 (63.3%)
Subjective OAB preop	63 (53.4%)	28 (48.3)	0.5
UUI preop	50 (42.0%)	19 (31.7%)	0.1
Preop VST/CST	114 (95%)	50 (83.3%)	0.6
Positive	34 (29.8%)	4 (8.0%)	0.002
Negative	80 (70.2%)	46 (92.0%)
UDS	113 (94.2)	36 (60%)	<0.0001
DO	27 (23.9%)	5 (13.9%)	0.2
ISD	24 (21.6%)	7 (20.0%)	0.8
Voiding pattern			0.6
Intermittent	23 (22.3%)	9 (26.5%)
Continuous	80 (77.7%)	25 (73.5%)
Mechanism of void
Valsalva	7 (7.0%)	2 (5.9%)	0.8
Detrusor	59 (59.0%)	18 (52.9%)
Combination	34 (34.0%)	14 (41.2%)
Max bladder capacity	390.7 (118.7)	369.3 (120.7)	0.4

Bold data indicates statistically significant.

BMI, body mass index; CST, cough stress test; DO, detrusor overactivity; ISD, intrinsic sphincter deficiency; max, maximum; OAB, overactive bladder; POP, pelvic organ prolapse; POP-Q, Pelvic Organ Prolapse Quantification System; preop, preoperative; SSLS, sacrospinous ligament suspension; SUI, stress urinary incontinence; UDS, urodynamic studies; USLS, uterosacral ligament suspension; UUI, urge urinary incontinence; VST, valsalva stress test.

For our primary composite outcome, sling failure was defined as either SUI symptoms (as defined by UDI-6 parameters if available or documentation of SUI), reoperation, or retreatment. The concomitant sling group had lower overall failure rates compared with the interval group (3.3% vs 25%, P = 0.0002; odds ratio [OR], 0.13; 95% confidence interval [CI], 0.04–0.4). One patient in the interval group had bulking injections for recurrent or persistent SUI and still reported SUI symptoms at the time of follow-up. There was no retreatment with nonsurgical measures in either group. We then analyzed the prospective and retrospective SUI symptom outcomes separately. Prospectively, there was less bothersome SUI (UDI-6 question 3) after concomitant sling (placement 3% vs 33%, P = 0.0002; OR, 0.07; 95% CI, 0.01–0.34), and similar findings were observed retrospectively (3% vs 27%, P = 0.002; OR, 0.1; 95% CI, 0.2–0.5).

Mean composite UDI-6 scores did not differ between groups (19.0 vs 18.6), and both displayed a relatively low level of urinary symptom bother after surgery. As determined by chart review, preoperative rates of OAB (53% vs 48%, P = 0.5) and urge urinary incontinence (UUI) (42% vs 32%, P = 0.12) were not different between the groups. The concomitant sling group showed significant improvement in OAB (53%–25%, P = 0.0004) and UUI (42%–14%, P < 0.0001). The interval group revealed persistent and slightly worsening postoperative OAB (48%–52%) and UUI (32%–40%) after the index surgery and before their interval sling. We were unable to obtain adequate OAB and UUI data on retrospective chart review after interval sling. For those with prospective follow-up, there were no differences between groups in frequent urination/OAB (34% vs 27%, P = 0.45) and UUI (41% vs 27%, P = 0.15) on the UDI-6. There were no differences between groups with regard to seeking treatment for OAB/UUI (8% vs 10%, P = 1.0). With regard to overall satisfaction of urinary symptoms, mean PGI-I scores did not differ between groups (2.4 vs 1.8, P = 0.15) with the majority (62% vs 83%) being “very much better” or “much better” (Table 2).

TABLE 2.

UDI-6 Outcomes

	Concomitant	Interval
	(n = 61)	(n = 30)	P
Do you usually experience frequent urination?	21 (34.4%)	8 (26.7%)	0.5
If yes, mean bother score	2.4 (0.9)	2.7 (1.4)	0.5
Do you usually experience urine leakage related to a feeling of urgency?	25 (41.0%)	8 (25.8%)	0.2
If yes, mean bother score	2.4 (1.2)	2.14 (1.1)	0.7
Do you usually experience urine leakage related to physical activity, coughing, or sneezing?	2 (3.3%)	10 (33.3%)	0.0002
If yes, mean bother score	3.00 (1.4)	1.9 (0.9)
Do you usually experience small amounts of urine leakage (that is, drops)?	10 (16.4%)	9 (30.0%)	0.1
If yes, mean bother score	2.6 (1.2)	2.0 (1.22)	0.3
Do you usually experience difficulty emptying your bladder?	11 (18.0%)	6 (20.0%)	0.8
If yes, mean bother score	2.1 (0.8)	1.8 (0.8)	0.6
Do you usually experience pain or discomfort in the lower abdomen or genital region?	7 (11.5%)	3 (10.0%)	1
If yes, mean bother score	3.1 (0.9)	2.7/4 (0.6)
Overall UDI-6 score	19.0 (13.8)	18.8 (16.4)	1
Describe how your urinary tract condition is now, compared with how it was before your surgery
1—Very much better	25 (41%)	15 (50.9%)	0.2
2—Much better	13 (21.3%)	10 (33%)
3—A little bit better	10 (16.4%)	2 (6.7%)
4—No change	5 (8.2%)	1 (3.3%)
5—A little bit worse	5 (8.2%)	2 (6.7%)
6—Much worse	3 (4.9%)	0
7—Very much worse	0	0
Overall PGI-I score	2.4 (1.5)	1.8 (1.2)

Question 3 (in bold): primary outcome measure.

PGI-I, Patient Global Impression of Improvement; UDI-6, Urogenital Distress Inventory Short-Form 6.

Preoperatively, 95% of the concomitant group versus 83% of the interval group had a CST result recorded, and patients in the concomitant group were more likely to undergo UDS (94.1% vs 60%, P < 0.0001) and were more likely to have a positive preoperative CST result (30% vs 8%, P = 0.002). For those who had UDS, there was no difference in rates of ISD (22% vs 20%, P = 0.8), DO (24% vs 14%, P = 0.2), voiding pattern, mechanism of void, or maximum bladder capacity as reported in the chart or individual UDS analysis (Table 1).

Complication rates were not different between the groups. Rates of bladder perforation/urethral injury were 2.5% and 3.5%, respectively. Urinary retention/voiding dysfunction after sling placement (8.3% vs 11.7%) was short-term (<1 week) with the exception of 1 patient in the concomitant group who had long-term (>6 weeks) retention that did not require reoperation or revision. Other complications included low rates of urinary tract infection (UTI) or recurrent UTI and surgical site infection (Table 3). Two patients in the concomitant group reported dyspareunia, but it is unclear if this was related to the sling or POP surgery. There was also 1 patient with granulation tissue and another with de novo chronic discharge in the concomitant group. There were no mesh exposures. Overall rate of complications was 17.5% in the concomitant group and 21.3% in the interval group (P = 0.6; OR, 0.8; 95% CI, 0.4–1.7).

TABLE 3.

Complications

	Concomitant	Interval
	(n = 120)	(n = 60)	P
Bladder perforation/urethral injury	3 (2.54%)	3 (3.45%)	0.3971
Urinary retention/voiding dysfunction	10 (8.3%)	7 (11.7%)	0.5
Mesh exposure/erosion	0 (0%)	0	1
Sling revision/removal	1	0	1
Other surgical complications	7 (5.88%)	3 (5%)	1
UTI/recurrent UTI	2 (1.68%)	2 (3.33%)
SSI	1 (0.8%)	1 (1.6%)
Dyspareunia	2 (1.68%)	0
Granulation tissue	1 (0.8%)	0
Chronic discharge	1 (0.8%)	0
Overall complications	21/120 (17.5%)	13/60 (21.3%)	0.6

SSI, surgical site infection; UTI, urinary tract infection.

DISCUSSION

In the OPUS trial,² despite a postoperative SUI rate of 43%, only 4.7% of women in the sham group proceeded to have SUI surgery. This demonstrates how rare interval slings are in the population of women with minimal or no SUI symptoms before their POP surgery, thus making their outcome data uniquely challenging to capture. Our study discovered an approximate 9-fold increased rate of postoperative SUI for interval slings compared with concomitant sings in both the prospective and retrospective follow-up. In addition, there only appears to be an increased level of “somewhat” bothersome SUI in the interval sling group (Table 2). It is worth noting that, preoperatively, these groups of patients were almost identical in terms of preoperative subjective SUI rates, age, BMI, preoperative POP-Q stage, type of sling used, and UDS parameters, including ISD and DO. Patients in the concomitant group were more likely to have a positive CST result preoperatively and more likely to undergo UDS, which may reflect the patient and health care provider decision and willingness to proceed with concomitant sling; however, there were no UDS parameters among the patients who had UDS done that predicted the SUI outcomes of this study. Patients in the interval sling group had a significantly higher rate of prior POP repairs, which could potentially be a predictor of poor tissue quality,¹² although their preoperative prolapse stage was less severe. It must be noted that a limitation of this study is the fact that the majority of patients in both groups underwent sacrocolpopexy with relatively low numbers of vaginal native tissue repairs, which may reflect the practice pattern during the period of when these data were collected. In the interval sling group, 5 patients underwent vaginal mesh hysteropexy, which is no longer commercially available. The higher rates of mesh augmented repairs (compared with current practice patterns), particularly in the interval group, may reflect a more dramatic correction of the anterior vaginal wall, unmasking more bothersome de novo stress incontinence in the interval group. However, the rates of de novo stress incontinence in the CARE (Colpopexy and Urinary Reduction Efforts) trial,¹³ which randomized patients without bothersome SUI undergoing abdominal sacrocolpopexy for POP with and without Burch procedure, were equivalent to the patients in the OPUS trial,² who underwent native tissue vaginal repair with mesh sling, suggesting that the mode of apical suspension is less important. In addition, there were minimal differences between preoperative and postoperative POP-Q stage in the concomitant and interval groups; although there were higher than expected rates of recurrent stage 3 and stage 4 prolapse in both groups, there were low rates of reoperation. The similarities between the postoperative POP-Q stages support the conclusion that the mode of apical suspension likely did not affect the results of this study. Ultimately, very little regarding preoperative characteristics of these patients would predict such a dramatic difference in rates of reported SUI with interval slings.

After the index surgery, patients in the interval sling group had predictably high levels of bother with their SUI, which prompted placement of the interval sling; this is likely a confounder, as these patients may have heightened awareness of their SUI symptoms because they experienced a period of leakage that was sufficient to prompt a separate sling procedure. The observation that women who lived with bothersome leakage for their interval period may have recall bias is further strengthened by the fact that patients in the interval group had higher satisfaction reflected in their postsling PGI-I scores, suggesting that the correction of their bothersome de novo SUI with a MUS was much more dramatic than the women in the concomitant group, who never experienced SUI because their slings were largely prophylactic. Indeed the 3–4% who experienced SUI after prophylactic sling placement may be even more frustrated with the lack of sling efficacy that was purported to prevent them from leaking. It should be noted that, in the concomitant group, retrospective chart review showed a postoperative SUI rate of 3.4%, which remained stable at 3.3% at an average follow-up time of 129.7 weeks (2.5 years). It should be noted that, with the exception of 1 patient who was retreated with coaptite, our failures are largely based on subjective symptoms and these data ultimately show that, despite differences in the rate of subjective SUI, both groups seem to be satisfied with their treatment, as reflected by their low UDI-6 scores.¹⁴

Additional benefits of concomitant sling placement at the time of POP surgery are supported by studies that show at least initial improvement in OAB/UUI with placement of a sling.¹⁵ In this study, postoperative rates of OAB/UUI in the interval group remained overall unchanged (if not slightly worsened) in the retrospective follow-up after the index surgery and before the interval sling, whereas these symptoms were improved by two thirds in the concomitant sling group. After placement of the interval sling, the data from the prospective follow-up showed that rates of OAB/UUI had decreased by approximately half in the interval group. In the concomitant group prospective follow-up, rates had returned to the preoperative baseline of 41.0%.

Other studies¹ have shown that, in patients with bothersome preoperative SUI (in contrast to this study, which investigated patients with minimal or no SUI symptoms), a staged sling approach can decrease the number of slings by approximately one third, under the assumption that this would decrease the potential for complications and mesh burden, despite our study showing a low rate of sling-related complications with no mesh exposures and only 1 revision for urethral pain and recurrent UTIs. However, in this same study,¹ 51% proceeded with SUI treatment and 37% ultimately underwent sling placement—there are no data revealing how those slings performed to compare with historical results of concomitantly placed slings in patients with preoperative SUI. There also remain unproven theories that a staged approach may produce a more “effective” sling because of corrected anatomy from the index prolapse repair. This study provides evidence suggesting that the potential for increased efficacy from staging a sling for corrected anatomy is unlikely.

Strengths of our study include collection of data from a multicenter cohort of patients at 7 separate academic institutions that include surgeons with differing practice patterns and a diversity of POP procedures. It is the largest study to specifically investigate the performance and outcomes of interval slings that are placed after an index POP surgery in women with minimal or no preoperative SUI symptoms, which were not able to be captured prospectively in the OPUS trial² because of the known fact that a small number of women ultimately pursue interval sling. Recognizing that this is a rare population made it necessary to identify these women retrospectively using multiple sites, which introduces significant bias into the population. Although not randomized, the 2 groups of patients were pulled from electronic medical records from a specific timetable, and patients were screened and enrolled in chronological order working backwards from most recent. For patients who were able to be contacted prospectively, validated questionnaires were used.⁸

Limitations include those inherent to retrospective cohort studies, such as the potential for selection bias, especially because the 2 groups of women in this study were chosen based on their desire or willingness to pursue SUI surgery and that the women who develop de novo incontinence that is sufficiently bothersome to prompt pursuing an additional surgery to address their SUI are phenotypically a different population. Because of low numbers of interval slings, our inclusion criteria allowed for a variety of sling types, which could potentially be a confounder, although there was only 1 fascial sling in each arm. It also must be noted that the threshold UDI-6 score that reflects bother sufficient to prompt second surgery is unknown. Patients in either group with a UDI-6 score of >1 (moderate bother or greater) were used as a definition of failure; however, it does not capture the threshold for retreatment, which represented a minority of failures included here. Additional limitations include the fact that only half of our cohort were able to be contacted to gather prospective data, and the prospective data used validated questionnaires with subjective outcomes, whereas the retrospective data were binary (“yes” or “no”), lacking subjectivity. However, our prospective and retrospective results for SUI symptoms are consistent in their findings even at different time points. This is strengthened by the fact that postoperative benefits of the concomitant sling were demonstrated in the robust retrospective cohort. The study did not include a retrospective chart review for OAB and UUI after the interval sling had been completed; in this regard, some of the secondary aims have less robust data for how interval slings improved OAB and UUI.

CONCLUSIONS

Among women with minimal or no SUI symptoms presenting for POP repair, concomitant slings have lower rates of de novo SUI postoperatively, despite higher rates of positive preoperative CST results and comparable rates of ISD compared with women who underwent interval slings for de novo bothersome SUI. Consistent with other studies,¹⁵ patients with concomitant slings may have the additional benefit of reducing their rates of postoperative OAB and UUI, without increasing their rates of complications compared with interval slings. Staging slings in women without preoperative SUI is a reasonable practice if the goal is to decrease the number of slings performed because few women ultimately proceed with second surgery. However, if the goal is to improve the success of SUI treatment, a staged or interval sling may result in worse outcomes compared with concomitant slings.