Introduction

The most common type of pelvic organ prolapse (PO) is anterior-compartment prolapse. Hendrix et al. demonstrated in a group of 16,616 postmenopausal women a prevalence of anterior-compartment prolapse of 34%, and this was much higher than the rates of apical- or posterior-compartment prolapse [1]. The aetiology of pelvic organ prolapse (POP) is complex and associated with various factors such as age, menopausal status and childbirth-related pelvic floor trauma [2, 3]. Possible surgical interventions include biological-graft, mesh and native tissue repair [4, 5]. The development of new surgical interventions is urgently required, and potential surgical interventions require robust evaluation. Selecting appropriate efficacy and safety outcomes is a crucial step in designing randomised trials. Outcomes collected and reported in randomised trials should be relevant to a broad range of stakeholders, including women with anterior-compartment prolapse, healthcare professionals and researchers. For example, resolution of bladder symptoms is an important outcome for all stakeholders; however, it is not commonly reported across trials. Even when outcomes have been consistently reported, secondary research methods, including pair-wise meta-analysis, may be limited by the use of different definitions and measurement instruments [6, 7]. A core outcome set should help address these issues. The first stage in core outcome-set development is to evaluate outcome and outcome-measure reporting across published trials. Therefore, we systematically evaluated outcome and outcome-measure reporting in published randomised trials evaluating surgical interventions for anterior-compartment prolapse. In addition, we assessed the relationships between outcome reporting quality with other important variables, including year of publication, impact factor and methodological quality.

Materials and methods

This systematic review is part of a wider project of the International Collaboration for Harmonising Outcomes, Research and Standards in Urogynaecology and Women’s Health (CHORUS) (i-chorus.org) and was registered with the Core Outcome Measures in Effectiveness Trials (COMET) initiative database, registration number 981, and with the International Prospective Register of Systematic Reviews (PROSPERO), registration identification CRD42017062456. We searched bibliographical databases comprising the Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE and MEDLINE from inception to September 2017. The search strategy used several MeSH terms, including bladder prolapse, cystocele and POP. Randomised trials evaluating surgical interventions for anterior-compartment prolapse were eligible. We included trials evaluating the surgical management of anterior prolapse as a unicompartmental prolapse procedure, as well as trials in which anterior repair was undertaken in addition to other surgical interventions. Non-randomised studies, observational studies and case reports were excluded.

Two researchers (CD and AE) independently screened the titles and abstracts of electronically retrieved articles. The articles potentially eligible for inclusion were retrieved in full text to assess eligibility, and reference lists were independently reviewed. Any discrepancies between the researchers were resolved by review of a third senior researcher (SKD). Two researchers (CD and AE) independently extracted the study characteristics, including year of publication, journal topicality (subspecialist, general obstetrics and gynaecology or general medicine), journal’s impact factor and commercial funding (yes/no). The journal’s impact factor was determined using InCites Journal Citation Reports (Clarivate Analytics, Thomson Reuters, New York, NY, USA). Funding status was identified by reviewing the article text and included the donation of equipment or other resources. Two researchers (CD and AE) independently assessed the methodological quality of included randomised trials using the modified Jadad criteria (score range 1–5) [8]. Studies were assessed as high quality when they achieved a score >4. Outcome reporting quality was assessed using the Management of Otitis Media with Effusion in Cleft Palate (MOMENT) criteria (score range 1–5) [9]. Studies were assessed as high quality when they achieved a score >4.

The non-parametric Spearman’s rank correlation coefficient (Spearman’s rho) was used to explore univariate associations between outcome reporting quality and impact factor during the year of publication, year of publication and methodological quality. Multivariate linear regression analysis using the Enter model was also undertaken to assess the combined association of quality of outcome reporting and journal type, impact factor during the year of publication, year of publication and methodological quality (independent variables) with outcome reporting (dependent variable). All tests were two-tailed. Statistical significance was set at 0.05, and analyses were conducted using the SPSS statistical software (IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY, USA).

This study was reported with reference to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement [6].

Results

In total, 2482 titles and abstracts were screened, and 231 potentially relevant studies were examined in detail (Fig. 1). Sixty-eight randomised trials, reporting data from 10,499 participants, met the inclusion criteria (Table 1) [5, 10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88]. Additionally, 12 randomised trials published long-term follow-up data [5, 22, 29, 39, 40, 64, 71, 72, 79, 81, 86, 87]

Fig. 1
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Study search and inclusion

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Table 1 Study characteristics
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Trials were published between 1985 and 2017, with most being published in subspecialty journals (33/80; 41%). Trials were frequently published in journals with an impact factor <3 [median = 2.7; interquartile range (IQR) = 2.2–4.3] and were generally small (median = 93; IQR = 60–154). Ten trials (14%) declared commercial funding. The methodological quality and outcome reporting quality varied considerably between trials (Table 1). One hundred different outcomes were organised into 11 thematic domains. The three most commonly reported thematic domains were presence of symptoms posttreatment (50 trials, 28 outcomes; 28 outcome measures), prolapse treatment success rates (47 trials; 3 outcomes; 16 outcome measures) and perioperative complications (46 trials; 15 outcomes; 13 outcome measures) (Table 2). Commonly reported outcomes were anatomical prolapse stage (43 trials; 54%), commonly assessed using the Pelvic Organ Prolapse Quantification (POP-Q) instrument (35 trials; 81%), QoL (25 trials; 31%); and intra- and postoperative complications (23 trials; 29%). Patient-reported outcomes were infrequently reported; for example, a minority of trials reported prolapse symptoms (9 trials; 11%), urinary symptoms (11 trials; 14%) and sexual dysfunction (14 trials; 17%) (Table 3). Eleven trials (14%) reported patient satisfaction.

Table 2 Most commonly reported outcome domains
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Table 3 Outcomes reported in 80 randomised controlled trials (RCTs) evaluating surgical management of anterior-compartment prolapse
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Forty-two randomised trials compared native tissue or biological graft versus mesh repair for anterior vaginal prolapse. Mesh-related complications were rarely reported: seven trials (9%) reported mesh erosion, six (7%) reported mesh shrinkage and a single trial (1%) reported the degree of morbidity associated with mess Only three trials (4%) evaluated cost effectiveness. One hundred and twelve different outcome measures wer reported (Table 4). Forty-six questionnaires were used as measurement instruments, most of which were validated (45; 98%). Anterior prolapse symptoms were measured using the Pelvic Organ Prolapse Urinary Incontinence Sexual Questionnaire (PISQ-12) (13 trials; 16%), Urogenital Distress Inventory (UDI-6) (11 trials; 14%) and the Pelvic Floor Distress Inventory (PFDI-20) (9 trials; 11%). QoL was measured using the Prolapse Quality of Life (P-QoL) (10 trials; 12%), Pelvic Floor Impact Questionnaire Short Form (PFIQ-7) (8 trials; 10%) and the Incontinence Impact Questionnaire Short Form (IIQ-7) (6 trials; 7%). Table 5 summarises our main findings, demonstrating the most frequently reported outcomes. It reveals the significant discrepancies in terms of outcome reporting.

Table 4 Outcome measures reported in 80 randomised controlled trials (RCTs) evaluating surgical management of anterior-compartment prolapse
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Table 5 Reported outcomes by by more than eight studies with greater than 93 participants (median value)
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We observed a moderate correlation between outcome reporting quality and year of publication in the univariate analysis (r 0.458; p  < .001) and study quality (r 0.409; p  < .001) (Table 6). The latter index significantly affected outcome reporting in the multivariate logistic regression (β = 0.412; p  = .018).

Table 6 Univariate and multivariate correlation with outcome reporting quality
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Discussion

Summary of main findings

This study demonstrated considerable variation in outcome and outcome-measure reporting across published trials evaluating surgical interventions for anterior-compartment prolapse. Commonly reported outcomes included normalised anatomy, QoL and pain. Patient-reported outcomes were infrequently reported, and a minority of trials reported on patient satisfaction. Mesh-related complications, including erosion, shrinkage and morbidity, were rarely reported. Forty-five different questionnaires were used as measurement instruments; most were validated. Only a few trials considered cost effectiveness.

Strengths and limitations

Strengths of our systematic review include originality, a rigorous search strategy and methodological robustness. To our knowledge, this systematic review is the first to evaluate outcomes and outcome measures in anterior-compartment prolapse trials. Study screening and selection and data extraction and assessment were conducted independently by two researchers to avoid bias. Our findings were based on outcome reporting in published randomised trials. The exclusion of observational studies may have potentially missed outcomes related to harm [89, 90] and selecting only trials reported in English may have introduced selection bias. The variation of interventions for correcting anterior prolapse may have caused variation in outcome and outcome-measure reporting.

Interpretation

Randomised trials require a substantial investment of resources. Variation in outcomes and outcome measures limits the ability of trials to be combined with meta-analyses, which contributes to inevitable research waste, as identified in various areas of women’s health, including childbirth trauma, endometriosis and pre-eclampsia [91,92,93,94]. This systematic review is the first step in the development of a minimum data set, which will be known as a core outcome set. It will be developed with reference to methods described by the COMET initiative, Core Outcomes in Women’s and Newborn Health (CROWN) initiative and other core-outcome-set development studies, including those on endometriosis, pre-eclampsia, termination of pregnancy, Twin-Twin Transfusion Syndrome and neonatal medicine [95,96,97,98,99].

CHORUS is aiming to work towards a standardisation of outcomes and outcome measures and subsequently establish a minimum of standards in research and clinical practice. Chorus working groups are currently evaluating reported outcomes in all areas of urogyneacology and have been registered with the COMET (registration number 981, http://www.comet-initiative.org/studies/details/981) and CROWN initiatives. Each working group has carefully considered the scope of its work [100], and CHORUS will replicate the success of other international initiatives that have standardised outcome selection, collection and reporting across preterm birth research [101].

In the absence of a core outcome, we recommend QoL (incorporating sexual function), postoperative complications, patient and physician satisfaction and postoperative prolapse, bladder and bowel symptoms be collected across all anterior prolapse trials.

Conclusion

Anterior-compartment prolapse trials report many different outcomes and outcome measures and often neglect to report important safety outcomes. Developing, disseminating and implementing a core outcome set will help address these issues.