The controversy surrounding mesh, including that used in stress urinary incontinence (SUI) surgery, has shone a spotlight on the need for robust evidence of treatment safety and efficacy. Heterogeneity in clinical trials evaluating surgical treatments of SUI has been reported (1) and importantly, variation in reported outcomes and outcome measures utilised impedes synthesis of data and limits quality of research conclusions.

Urinary incontinence is an important condition that affects 27.6 % of women worldwide (2) and significantly impacts quality of life. There is substantial economic burden with SUI treatment costing the National Health Service in the UK £117million/year (3). Given the nature of the condition and disease burden with regards to quality of life, patient reported outcomes and how we measure these outcomes using patient reported outcome measures (PROMs) should arguably have a key focus in research trials.

No consensus currently exists regarding the use of PROMs in research trials evaluating SUI surgery. As part of the first step in developing a core outcome measure set (COMS), a consensus-based set of outcome measures recommended for use in research trials, we aimed to systematically review RCTs evaluating surgical procedures for stress urinary incontinence, extract patient reported outcome measures used and create a comprehensive, structured inventory.

We conducted a secondary analysis and update of a previous systematic review (1). Medical Subject Headings (MeSH terms) were used to search databases including MEDLINE, Embase and Cochrane for RCTs evaluating surgical treatments for SUI from inception to January 2020. Predefined eligibility criteria included publication in English language and adult, female-only subjects. Non-randomised and retrospective trials and trials involving men were excluded. Our search strategy yielded 123 eligible RCTs for analysis. 
 All patient reported outcomes and outcome measures reported in these RCTs evaluating surgical treatments for SUI were extracted. We grouped the PROMs into a structured inventory including reporting frequency and evidence of previous validation studies, and assigned PROMs to domains based on predominant theme.

A total of 123 eligible RCTs were evaluated. Total participants ranged from 20 to 655, and follow up duration was between 2 and 100 months, mean 22 months. 116 RCTs (94%) included patient reported outcomes with 44 different PROMs utilised in total. Figure 1 shows the range and frequency of PROMs included in the eligible RCTs.
FIGURE 1
The five most commonly reported PROMs were Patient Global Impression of Improvement (PGI-I), Urogenital Distress Inventory (UDI-6), bladder diary, International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-UI SF) and Incontinence Impact Questionnaire, Short Form (IIQ-7).
Bladder diary duration ranged from 2 to 14 days. IIQ and IIQ-7 were used 32 times in total, but IIQ-7 used most often, in 21 RCTs. PROMs were grouped into 6 domains: generic, quality of life, bladder specific, pelvic floor specific, SUI and sexual function. 

Figure 2 demonstrates the PROMs within each domain. PROMs with overlapping themes are represented by overlapping bubbles, but were allocated to their domain based on the predominant theme. The numbers under each PROM denote the number of RCTs that utilised them.

FIGURE 2

We performed a preliminary analysis of validation of included PROMS. The majority are validated and have demonstrated good internal consistency in previously published studies, a parameter generally taken as a measure of scale reliability. It can be measured by Cronbach's alpha score, with values above 0.7 indicating acceptable internal consistency. Studies have reported Cronbach's alpha values of 0.71 and 0.74 for ICIQ and UDI respectively.

Our study has demonstrated that despite the quality of life nature of the complaint of SUI, not all trials evaluating surgical treatments include patient reported outcomes. Of those that do, there is variation in the outcome measures used to evaluate safety and efficacy. Only 5 PROMs were used in more than 20 trials, and 34% (15/44) of the PROMs featured in only one RCT. The varied methods of measuring patient reported outcomes contributes to the difficulty in synthesising results and ultimately hinders meta-analyses and interpretation of research data. Of the most commonly used PROMs there is evidence of internal consistency but not all PROMs used have evidence of reliability or validity.

Patient reported outcomes, and consequently patient reported outcome measures, are frequently used in SUI research, which reflects the subjective nature of SUI surgical treatment efficacy. However there is variation in the type of PROMs used with no current consensus or agreement amongst relevant stakeholders for a defined set of patient reported outcome measures. We propose that this consensus is required to standardise measurements, harmonise research reporting and promote use of validated and reliable outcome measures. In addition, further validation studies to assess internal consistency and validity are warranted as part of the development process of a core outcome measure set. This systematic review forms the first step in the development of a COMS by assessing and evaluating the current patient reported outcome measures used.

Doumouchtsis, SK, Pookarnjanamorakot, P, Durnea, C, Zini, M, Elfituri, A, Haddad, JM, Falconi, G, Betschart, C, Pergialiotis, V, CHORUS, An International Collaboration for Harmonising Outcomes, Research, and Standards in Urogynaecology and Women's Health (i-chorus.org). A systematic review on outcome reporting in randomised controlled trials on surgical interventions for female stress urinary incontinence: a call to develop a core outcome set. BJOG 2019; 126: 1417– 1422.
Minassian VA, Drutz HP, Al-Badr A. Urinary incontinence as a worldwide problem. Int J Gynaecol Obstet. 2003 Sep;82(3):327-38. doi: 10.1016/s0020-7292(03)00220-0. PMID: 14499979.
Turner DA, Shaw C, McGrother CW, et al. The cost of clinically significant urinary storage symptoms for community dwelling adults in the UK. BJU Int 2004;93:1246–52