Materials and Methods

This prospective observational cohort study is part of an ongoing outcome quality registration project of Radboud University Medical Centre (Nijmegen, The Netherlands), which has been approved by Arnhem-Nijmegen Human Research Committee (April 2006). The present analysis included the 12 month follow-up data of consecutively performed trocar-guided, tension-free vaginal mesh procedures (Prolift; Ethicon) between September 2005 and April 2010. Details of 150 patients in this cohort have previously been reported in a study focusing on de novo prolapse in untreated vaginal compartments, and 93 were part of a randomized controlled trial, comparing mesh with native tissue repair in recurrent prolapse.

Inclusion criteria were increased risk of recurrence, which was considered recurrent pelvic organ prolapse stage II or higher or primary pelvic organ prolapse stage III or higher. Exclusion criteria were (contemplating) pregnancy or a compromised immune system.

Surgery was performed by17 gynecologists in 13 collaborating centers. The range of procedures varied from 1 to 209 (mean 25; median 3). Four performed more than 25 procedures. All gynecologists were trained for the tension-free vaginal mesh procedure as described by Fatton et al. Depending on the prolapsed compartment, mesh insertion could be anterior, posterior, anterior and posterior (in case of uterus or cervix in situ), or total (in case of a prolapsed vaginal vault).

Concomitant native tissue repairs were allowed for other less prolapsed compartments or compartments that were not at increased risk of recurrence. To reduce the risk of mesh exposure, simultaneous hysterectomy or T-incisions were avoided. For most of the participating centers, it was policy not to simultaneously insert a mid urethral sling because of anticipated increased risk on postoperative urinary retention. Patients were counseled on this strategy and the possibility of a second procedure. In case the presence of stress urinary incontinence after surgery necessitated the insertion of a midurethral sling, this was not considered a reintervention for POP and thus not registered as failure; on the other hand, the symptomatic recurrence of POP that necessitated resurgery was a reintervention for POP and thus counted as a failure.

All procedures were performed under perioperative antibiotic prophylaxis. Patients received an indwelling catheter for 1-2 days and a vaginal gauze pack for 24 hours.

Postoperative urinary retention was defined as repeated postvoid residual volume greater than 100 mL measured with a bladder scanner. De novo stress urinary incontinence was considered significant if a patient responded yes or moderately to quite a bit to the following question: do you experience urinary leakage during physical activity, coughing, or sneezing?

The mesh used in the original trocar-guided mesh procedure is monofilament polypropylene mesh, weighing 45 g/m ² . In 2009, some centers started using a partially absorbable mesh, consisting of a 50-50 blend of monofilament, nonabsorbable polypropylene and absorbable polyglecaprone 25 (Prolift+M; Ethicon). The technique is identical, but the mesh weighs 57 g/m ² before absorption and after full absorption after 90-120 days, only 31 g/m ² .

Baseline evaluation included medical history and assessment of POP by using the Pelvic organ Prolapse Quantification (POP-Q) system. Data on symptoms and bother were obtained by the standard Dutch urogynecological questionnaire, which among others contains the Dutch validated version of the Urogenital Distress Inventory (UDI).

Follow-up visits were scheduled at 6 weeks and 6 and 12 months. At 12 months a POP-Q examination was performed and patients were again requested to complete the standard urogynecological questionnaire.

Failure outcomes were defined as follows: (1) outcome I was an NIH failure of mesh-treated compartment, POP stage of II or greater of mesh-treated vaginal compartment(s) or resurgery for POP in mesh-treated compartments within 12 months; (2) outcome II was an NIH failure of overall POP or leading edge of prolapse in any compartment stage of II or greater or resurgery for POP in any compartment within 12 months; or (3) outcome III was an composite outcome failure or a leading edge of any compartment greater than hymen and the presence of bulge symptoms or resurgery for POP within 12 months.

The presence of bulge symptoms was defined as clinically significant if a patient responded yes or moderately to quite a bit to either of the 2 following questions: do you see or do you feel a vaginal bulge?

To determine the minimum sample size, we anticipated on a 90% success rate for the mesh-treated compartments. We considered treatment successful if the 1 sided 95% confidence interval (CI) did not fall below 85%. This resulted in a minimum number of 282 patients that were necessary for inclusion in this study.

Results are summarized as numbers with corresponding percentages or as medians with range. Primary outcomes were failure percentages with 95% CIs per predefined outcome definition. Univariable logistic regression was used to identify possible risk factors of failure in each of the outcomes. Considered risk factors were the patient’s age, menopause, previous POP repair(s), parity, preoperative POP stage, body mass index, location of mesh insertion, the use of the new partially absorbable mesh, mesh combined with native tissue repairs, mesh combined with sacrospinous fixation, the presence of the uterus, operating time, blood loss, complications, and mesh exposure.

Crude odds ratios (ORs) for the possible risk factors of failure for each outcome were calculated with corresponding 90% CIs. To optimize the validity of the logistic model, restriction of the number of test variables was necessary. To ensure that the number of events per variable (EPV) did not drop below 10, only the allowed number of the most significant variables was selected for entry in the multivariable model. Multivariable logistic regression with forward selection was used to identify those variables that were independently related to failure in each of the outcomes. Variables reaching statistical significance at the P < .10 level in the univariable analysis were considered valid for entry in the forward selection model. The adjusted OR with 95% CI are presented. A P value of < .05 was considered statistically significant. Statistical analysis was performed using SPSS 18.0 for Windows (SPSS, Inc, Chicago, IL).

Results

Four hundred thirty-three women met the inclusion criteria for trocar-guided mesh surgery and were included. Four hundred nineteen (97%) completed the 12 month follow-up. Baseline characteristics and preoperative POP stage are presented in Table 1 . The median age of the patients was 64 years (range, 16–93). Seventy-two percent of the patients had a recurrent POP and 67% a POP stage of stage III or greater.

Table 2 shows peri- and postoperative data. Eighteen percent of patients (n = 77) underwent surgery with a partially absorbable mesh. According to the 12 month follow-up questionnaire, 38 of 280 patients (13.6%) were classified as having de novo stress urinary incontinence.

Table 3 shows failure rates per location of mesh insertion for all predefined outcomes. NIH failure of the mesh-treated compartments POP stage of II or greater was 15% (95% CI, 12–19). NIH failure of overall POP stage of II or greater was 41% (95% CI, 36–45) and composite failure was 9% (95% CI, 7–13). Resurgery was performed in 18 of 433 patients (4%), of which 16 (89%) were in the untreated vaginal compartments. Highest failure rates were observed for combined anterior/posterior mesh insertions.

Table 4 shows crude ORs with 90% CIs per outcome definition for each of the tested variables. Variables that reached statistical significance at the P < .10 level were considered valid for entry in the multivariable logistic regression model. Because outcome I resulted in just 64 failures, we selected only 7 of the 9 most significant variables for entry in the multivariable regression model.

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