ABSTRACT
Study question Do subgroups of women with chronic pelvic pain (CPP) report different clinical symptoms and differing impact of pain on their quality of life? Summary answer Clinical profiles of women with CPP show variability of clinical symptoms both within and between subgroups. However, there is an obvious negative impact of pain on the patients’ lives across all subgroups with the comorbid endometriosis and bladder pain symptoms group (EABP) presenting with the higher pain intensities and the lower quality of life. What is known already CPP is a common condition affecting up to 26.6% of women, with many suffering for several years before diagnosis and/or treatment. The clinical presentation of CPP is varied and there are frequently comorbid conditions both within and outside the pelvis. Evidence from the literature show that there is an overlap of symptoms in chronic pain conditions whatever the underlying cause which suggests that chronic pain could be a condition itself. Study design, size, duration The study is part of The Translational Research in Pelvic Pain (TRiPP) project ( https://www.imi-paincare.eu/PROJECT/TRIPP/ ) which is a cross-sectional observational cohort study. The present study includes 769 female participants sampled from two existing endometriosis-focused cohort studies in Oxford, UK and Boston, MA, USA and newly recruited from the Instituto de Biologia Molecular e Celular (IBMC)) in Porto. The participants completed an extensive set of questions derived from standardised WERF EPHect questionnaires. Within this study population we defined a control group (reporting no pelvic pain, no bladder pain syndrome (BPS), and no endometriosis diagnosis, N=230) and four pain groups: endometriosis-associated pain (EAP, N=237), (BPS, N=72), comorbid endometriosis-associated pain and BPS (EABP, N=120), and pelvic pain only (PP, N=127). Participants/materials, setting, methods All participants were women of reproductive age (13-50 years) and were recruited at three different sites: Oxford (University of Oxford), Boston (Boston Center for Endometriosis (BCE)) and Porto (Instituto de Biologia Molecular e Celular (IBMC)). The questionnaire included: demographics; reproductive history; pelvic pain intensity assessed using 10-point numerical rating scales (NRS) for dysmenorrhoea, non-cyclical pain, dyspareunia and bladder pain; medical comorbidities; factors relieving and worsening pain; quality of life assessed using the SF-36 questionnaire; and pain catastrophising. Main results and the role of chance The EAP (Mean:7.37) and EABP (Mean:7.88) groups scored higher on the pain intensity scales for non-cyclical pelvic pain than the PP (Mean:6.82) group (p<0.001) and higher on the dysmenorrhoea scale than both the BPS and PP groups (p<0.001). The EABP (Mean:6.61) and BPS (Mean:6.52) groups had significantly higher bladder pain scores than the EAP (Mean:0.95) and PP (Mean:0.78) (p<0.001). The EABP group also had significantly higher pain scores for dyspareunia (p<0.001), even though more than 50% of participants (who were sexually active) in each of the pain groups reported interrupting and/or avoiding sexual intercourse due to pain in the last 12 months. Exploring the factors reported to worsen or relieve pain found that across the pain groups the three most reported factors for worsening pelvic pain were: stress (23.6%), full bladder/urinating (23.3%) and exercising (20.2%). The most common factors for relieving pelvic pain were: pain medication (31.4%), lying down (31.0%), and use of a heat pad (29.5%). Analysis of the quality-of-life questionnaire (SF-36) subscales revealed significant differences between the study groups across all SF-36 subscales (p<0.001). In line with the pain results the EABP group reported the negative highest impact across all the health measures while the PP group’s profile was closest to the control group’s profile. Significant effects were also observed between the pain groups for pain interference with their work (F(3,209)=9.76, p<0.001) and daily lives (F(3,244)=10.51, p<0.001), with the EABP suffering more compared to the EAP and PP groups (p<0.001). Limitations, reasons for caution Data for this study were derived predominantly from existing cohorts where data have been collected over time and thus different versions of questionnaires have been used. Thus, for some questions only a subgroup may have had an opportunity to complete the measure of interest. Recruitment of participants was impacted due to the COVID-19 pandemic. As a result, sample sizes overall were smaller than originally designed, and our BPS group was predominantly identified from gynaecological rather than urological clinics making it potentially different from other published BPS cohorts. Wider implications of the findings Overall, our results demonstrate the negative impact that chronic pain has on CPP patients’ quality of life and suggests that further exploration of interventions targeting quality of more broadly is important. Furthermore, it demonstrates the importance of dyspareunia in women with CPP, highlighting the need for more research in this area. Importantly, we show significant differences between the sub-groups of CPP suggesting the need for better patient stratification in future clinical studies and trials. However, the marked variability both within and between CPP sub-groups raises the question whether subgrouping on the basis of clinical diagnosis is the most appropriate strategy or whether alternative approaches could be identified allowing prioritisation of treatments better suited to the individual patient. Study funding/competing interest(s) This project has received funding from the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement No 777500. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and EFPIA Companies. Financial support was provided by the J. Willard and Alice S. Marriott Foundation for establishment of and baseline data collection within the A2A cohort - from which the Boston-based TRiPP population was sampled. Trial registration number NCT04001244