A core outcome set for research and clinical practice in women with pelvic girdle pain: PGP-COS

Alexandria Remus; Valerie Smith; Annelie Gutke; Juan Jose Saldaña Mena; Siv Mørkved; Lena Nilsson Wikmar; Birgitta Öberg; Christina Olsson; Hilde Stendal Robinson; Britt Stuge; Francesca Wuytack

doi:10.1371/journal.pone.0247466

. 2021 Feb 25;16(2):e0247466. doi: 10.1371/journal.pone.0247466

A core outcome set for research and clinical practice in women with pelvic girdle pain: PGP-COS

Alexandria Remus ^1,^*, Valerie Smith ¹, Annelie Gutke ², Juan Jose Saldaña Mena ³, Siv Mørkved ⁴, Lena Nilsson Wikmar ^5,⁶, Birgitta Öberg ⁷, Christina Olsson ⁶, Hilde Stendal Robinson ⁸, Britt Stuge ⁹, Francesca Wuytack ¹

Editor: Kathleen Finlayson¹⁰

¹School of Nursing & Midwifery, Trinity College Dublin, Dublin, Ireland

²Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg, Göteborg, Sweden

³Universidad Estatal del Valle de Ecatepec, Ecatepec de Morelos, Mexico

⁴Department of Public Health and Nursing, Norwegian University of Science and Technology, Trondheim, Norway

⁵Division of Physiotherapy, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden

⁶Academic Primary Healthcare Centre, Stockholm, Sweden

⁷Department of Medicine and Health, Linköping University, Linköping, Sweden

⁸Department of Interdisciplinary Health Sciences, Institute of Health and Society, University of Oslo, Oslo, Norway

⁹Division for Neuroscience and Musculoskeletal Medicine, Oslo University Hospital, Oslo, Norway

¹⁰Queensland University of Technology, AUSTRALIA

Competing Interests: The authors have declared that no competing interests exist.

^✉

* E-mail: alexandria.remus2@gmail.com

Roles

Alexandria Remus: Data curation, Formal analysis, Investigation, Methodology, Project administration, Writing – original draft, Writing – review & editing

Valerie Smith: Conceptualization, Funding acquisition, Investigation, Methodology, Project administration, Supervision, Writing – review & editing

Annelie Gutke: Data curation, Funding acquisition, Investigation, Methodology, Writing – review & editing

Juan Jose Saldaña Mena: Data curation, Funding acquisition, Investigation, Writing – review & editing

Siv Mørkved: Funding acquisition, Investigation, Writing – review & editing

Lena Nilsson Wikmar: Data curation, Funding acquisition, Investigation, Writing – review & editing

Birgitta Öberg: Data curation, Funding acquisition, Investigation, Writing – review & editing

Christina Olsson: Data curation, Funding acquisition, Investigation, Writing – review & editing

Hilde Stendal Robinson: Data curation, Funding acquisition, Investigation, Writing – review & editing

Britt Stuge: Data curation, Funding acquisition, Investigation, Writing – review & editing

Francesca Wuytack: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Project administration, Supervision, Writing – review & editing

Kathleen Finlayson: Editor

PMCID: PMC7906405 PMID: 33630941

Abstract

Background

Inconsistent reporting of outcomes in clinical trials of women with Pelvic Girdle Pain (PGP) hinders comparison of findings and the reliability of evidence synthesis. A core outcome set (COS) can address this issue as it defines a minimum set of outcomes that should be reported in all clinical trials on the condition. The aim of this study was to develop a consensus-based COS for evaluating the effectiveness of interventions in PGP during pregnancy and postpartum for use in research and clinical practice.

Methods

A systematic review of previous studies on PGP and semi-structured interviews with women were undertaken to identify all outcomes that were reported in prior studies and that are relevant to those experiencing the condition. Key stakeholders (clinicians, researchers, service providers/policy makers and individuals with PGP) then rated the importance of these outcomes for including in a preliminary PGP-COS using a 3-round Delphi study. The final COS was agreed at a face-to-face consensus meeting.

Results

Consensus was achieved on five outcomes for inclusion in the final PGP-COS. All outcomes are grouped under the “life impact” domain and include: pain frequency, pain intensity/severity, function/disability/activity limitation, health-related quality of life and fear avoidance.

Conclusion

This study identified a COS for evaluating the effectiveness of interventions in pregnancy-related and postpartum-related PGP in research and clinical settings. It is advocated that all trials, other non-randomised studies and clinicians in this area use this COS by reporting these outcomes as a minimum. This will ensure the reporting of meaningful outcomes and will enable the findings of future studies to be compared and combined. Future work will determine how to measure the outcomes of the PGP-COS.

Core outcome set registration

This PGP-COS was registered with COMET (Core Outcome Measures for Effectiveness Trials) in January 2017 (http://www.comet-initiative.org/studies/details/958).

Introduction

Pelvic Girdle Pain (PGP) during and after pregnancy is a common complaint reported by women worldwide. It affects up to two thirds of women at some point during pregnancy and can persist postpartum [1–7]. PGP is a significant cause of disability, negatively affects quality of life and is one of the leading contributors to employee absenteeism during pregnancy [8–14]. The effects of PGP have a large economic, social and psychological impact on individual families and society, resulting in an urgent need for effective interventions worldwide. Although various interventions for the prevention and treatment of PGP have been studied, the resulting evidence is difficult to interpret due to, in part, the large variety of outcomes reported across studies [15, 16]. For example, a systematic review on physiotherapy modalities including 58 articles could not perform any meta-analysis due to heterogeneity across studies [15]. The inability to meta-analyse outcome data results in relying on evidence from smaller individual studies that provide lesser quality evidence to identify effective interventions. Additionally, recent work from Wutack and O’Donovan identified 46 different outcomes measured across 107 intervention studies or systematic reviews of interventions for PGP [17]. They also identified that different studies often use a variety of measurement instruments to capture the same outcomes. This heterogeneity in reported outcome measures is problematic not only for direct comparison between studies, but it also limits the ability for the aggregation of data across trials, which renders the translation to clinical practice difficult and sometimes impossible [18]. The ability to pool data and compare across studies would allow for robust meta-analyses which, in turn, will aid in determining the most effective interventions for PGP.

One approach to overcome the lack of uniformity in reported outcome measures is to develop a core outcome set (COS). A COS is a standardised set of outcomes which should be measured and reported, as a minimum, in all studies for a specific health area or condition [19]. A COS allows for findings to be combined, compared and contrasted, reduces potential for reporting bias and ensures that the data are useful and usable, but does not restrict researchers from measuring additional outcomes at their discretion. A PGP-COS would assist in promoting the health and well-being of women with pregnancy and postpartum related PGP through consistent and relevant outcome reporting worldwide.

The aim of our study was to develop a consensus-based COS for PGP during pregnancy and postpartum at should be used, as a minimum, for use in research and clinical practice.

Methods

The study was prospectively registered in the COMET (Core Outcome Measures in Effectiveness Trials Initiative) database (Registration number: 958; http://www.comet-initiative.org/studies/details/958) and a detailed protocol was published [18]. The complete PGP-COS study involves five phases (Fig 1). Phase 1 [17], systematic review, has already been reported and phase 4 and 5 are in progress. In this paper, we focus on reporting the conduct and results of phases 2 and 3 and adhere to the Core Outcome Sets-STAndards for Reporting (COS-STAR) criteria and COMET guidance [20, 21]. Ethical approval for the study was granted from the lead researcher’s University’s Research Ethics Committee.

Phase 1: Preliminary list of outcome measures

Phase 1 resulted in identifying 53 outcomes for use in phase 2, the Delphi study. Of these outcomes, 45 were identified in the systematic review [17] and 8 were identified via 15 interviews with women who experienced PGP during pregnancy or postpartum from three countries; Ireland (n = 5), Sweden (n = 5) and Mexico (n = 5). These women were recruited via physiotherapy and chiropractic clinics and provided written informed consent for interviews. Following review, these outcomes were grouped by outcome domain using the OMERACT filter 2.0 framework [22] (Table 1) and forwarded for use in phase 2. It is important to note that domain classification for potential outcomes identified in the literature is consistent with what was reported during phase 1 of the PGP-COS development [17].

Table 1. Preliminary outcomes.

Life Impact	Economic Impact & Resource-Use Impact	Pathophysiological Manifestations & Clinical Tests	Adverse Events
n = 30	n = 5	n = 16	n = 2
Pain behaviour	Work ability	Anthropomorphic outcomes (BMI, height, weight, etc.)	Maternal adverse events/undesirable side effects
Pain character/type	Work performance	Body flexibility	Unborn/born child adverse events/undesirable side effects
Pain frequency	Analgesia use	Functional mobility
Pain intensity/severity	Cost	Gait endurance
Pain location	Healthcare utilisation	Gait speed
Full pain recovery		Maternal pregnancy outcomes
Function/disability/activity limitation		Muscle endurance
Physical activity levels/exercise limitations		Muscle strength
Need for a mobility aid		New born outcomes
Perceived body imbalance		Outcomes from pain provocation/location tests
Sexual functioning		Posture
Health related quality of life		Pubis Symphysis mobility
Health status		Recovery of symptoms
Family life impact		Step length
Social life impact		Surgical outcomes
Patient expectation of treatment		Urinary Incontinence
Patient satisfaction with life
Patient satisfaction with treatment
Anxiety
Confidence
Depression
Dependence on others
Emotional symptoms
Fear avoidance
Frustration
Pain catastrophizing
Self-efficacy
Well-being
Fatigue
Sleep function

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Phase 2: An international Delphi study

Participant selection and recruitment

A 3-round online Delphi study was used to reach consensus on the preliminary COS. Participants were recruited, internationally, from five PGP stakeholder groups: (1) clinicians, (2) patient representatives, (3) researchers, (4) researchers also working clinically and (5) policy makers and service providers. Potential participants were invited through mass invitational email (researchers identified from PubMed), professional organisations (such as world chiropractic, physiotherapy, surgical, osteopathic, patient, etc. groups) and social media (Facebook and Twitter). Snowball sampling was further encouraged. Invitees were provided with access to our online Participant Information Leaflet (PIL) which outlined the need for the study, the principles of a COS and what taking part in the study would involve. Access to the Delphi survey link was also provided as part of the invitation. Only potential participants that provided informed consent in the appropriate consent section were able to proceed with the Delphi survey. Study participants were pseudonymised and blinded to all other study members and participants by one researcher who managed this process (AR).

Delphi procedure

The surveys for each of the Delphi rounds were created using Google forms [23]. Each round was open for 21 days. During the second and third rounds, a reminder email was sent to all non-responders seven days before the survey closed. Non-responders after each round closed were not invited to the subsequent round. Participants were sent a copy of their survey responses after each round for reference in completing the subsequent round.

The round 1 survey presented the 53 outcomes identified in phase 1 (Table 1). A lay definition and/or examples were provided for outcomes where deemed necessary (S1 Table). Participants were asked to rate the importance of each outcome for inclusion in a PGP-COS using one of two rating scales; 5-point scale or a 9-point scale (Table 2), which the participants were randomly allocated to when they clicked the survey link. The use of these two scales was included as part of an embedded methodological study comparing the potential effect of different scales on the final outcomes in a COS development [18]. This embedded study was included in the development of the PGP-COS to explore the impact of different rating scales on the final COS. There is currently no consensus on which rating scale should be used in COS development and, as such, different scales have been used in previous COS. The results of the embedded methodological study are reported elsewhere [24]. During the Delphi study, however, any outcome rated as important on either scale (Table 2), as per our consensus definition detailed below, was forwarded to the subsequent round. During round 1, participants were also given the opportunity to add up to three outcomes not identified in the preliminary list that they believed were important to be included in the COS using free-text responses.

Table 2. Rating scales.

5-point scale		9-point scale
1–2	Not important	1–3	Not important
3	Unsure of importance	4–6	Unsure of importance
4–5	Important	7–9	Important

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In addition to their individual round 1 results, participants in round 2 were presented with the proportion of participants in each stakeholder group who rated each outcome as “important”. Participants were then asked to re-rate the importance of each outcome for inclusion in the PGP-COS using the same scale they were randomly allocated in round 1 (5-point or 9-point) and to rate the importance of any new outcomes added following round 1 (S1 Table).

In accordance with the COMET guidelines, outcomes forwarded from round 2 to round 3 were determined a priori based on consensus defined as ≥70% participants rating the outcome as “important” by three of the five stakeholder groups, one of which must have been the patient representative group [21, 25]. In round 3, participants were presented with the results from round 2, and were asked to re-rate the importance of each outcome for inclusion in the final PGP-COS.

Following round 3, outcomes were classified as “consensus in” (reaching a priori consensus) or “no consensus” (anything else). All outcomes that reached “consensus in” on the 5- and 9-point rating scales were combined to form the list of outcomes for discussion at the face-to-face consensus meeting.

Consensus meeting

Agreement on the final PGP-COS was achieved at a 1-day face-to-face consensus meeting held on October 27^th, 2019, in Antwerp, Belgium. The meeting was chaired by VS and led by AR, neither of whom had a vote on the outcomes at the meeting. Participants were eligible to attend the consensus meeting if they completed all 3 rounds of the Delphi survey and indicated an interest in attending the meeting by ticking a box on the round 3 survey. To ensure representation across stakeholder groups, Delphi study participants who indicated their interest in attending were sorted by stakeholder group and then randomly chosen to attend using a random number generator. International representation was also monitored as part of this process and was adequately achieved.

During the consensus meeting participants were presented with the list of outcomes resulting from the Delphi study. Each outcome, in turn, was individually considered by the consensus panel, and fully discussed. Following discussion, the panel members voted on the critical importance of including the outcome measure in the final PGP-COS. A priori consensus for the face-to-face consensus meeting was determined as ≥ 70% of all members voting “yes” for the inclusion of an outcome measure in the final PGP-COS. Voting was anonymous using smart technology and the Poll Everywhere (www.polleverywhere.com). At the end of voting, outcome measures that reached “consensus in” were presented to the consensus meeting panel for final consideration and agreement on inclusion in the final PGP-COS.

Results

Delphi study

Participant demographics for all three Delphi rounds are presented in Table 3. Overall, 205 stakeholders from 32 countries completed round 1. Of these, 147 (72%) completed round 2 and, of these, 132 (90%) completed round 3. This provided an overall Delphi retention rate of 64%.

Table 3. Delphi study participant characteristics.

Stakeholder Group n (%)	Round 1 (n = 205)	Round 2 (n = 147)	Round 3 (n = 132)
Clinician	91 (44%)	59 (40%)	52 (39%)
Clinician Researcher	38 (19%)	33 (22%)	33 (25%)
Patient	42 (20%)	26 (18%)	18 (14%)
Researcher	23 (11%)	21 (14%)	21 (16%)
Service Provider/Policy Maker	11 (5%)	8 (5%)	8 (6%)
Gender n (%)	Round 1 (n = 205)	Round 2 (n = 147)	Round 3 (n = 132)
Female	159 (78%)	114 (78%)	10 (77%)
Male	45 (22%)	33 (22%)	23%
Prefer not to say	1 (0%)	0 (0%)	0 (0%)
Age n (%)	Round 1 (n = 205)	Round 2 (n = 147)	Round 3 (n = 132)
18–24	3 (1%)	1 (1%)	1 (1%)
25–34	41 (20%)	28 (19%)	22 (17%)
35–44	74 (36%)	51 (35%)	44 (33%)
45–54	44 (21%)	35 (24%)	33 (25%)
55–64	33 (16%)	26 (18%)	26 (20%)
65+	10 (0%)	6 (4%)	6 (5%)
Country n (%)	Round 1 (n = 205)	Round 2 (n = 147)	Round 3 (n = 132)
Argentina	1 (0%)	0 (0%)	0 (0%)
Australia	8 (4%)	6 (4%)	6 (5%)
Austria	1 (0%)	1 (1%)	1 (1%)
Belgium	4 (2%)	4 (3%)	4 (3%)
Brazil	1 (0%)	1 (1%)	1 (1%)
Canada	17 (8%)	13 (9%)	13 (10%)
Colombia	1 (0%)	1 (1%)	1 (1%)
Cook Islands	1 (0%)	0 (0%)	0 (0%)
Croatia	1 (0%)	0 (0%)	0 (0%)
Denmark	3 (1%)	3 (2%)	3 (2%)
Egypt	1 (0%)	0 (0%)	0 (0%)
Finland	1 (0%)	1 (1%)	1 (1%)
Germany	1 (0%)	1 (1%)	1 (1%)
Iceland	1 (0%)	0 (0%)	0 (0%)
Iran	2 (1%)	2 (1%)	2 (2%)
Ireland	45 (22%)	31 (21%)	24 (18%)
Israel	1 (0%)	1 (1%)	1 (1%)
Malaysia	4 (2%)	2 (1%)	2 (2%)
Mexico	3 (1%)	3 (2%)	2 (2%)
Nepal	2 (1%)	2 (1%)	2 (2%)
Netherlands	4 (2%)	4 (3%)	4 (3%)
New Zealand	3 (1%)	2 (1%)	2 (2%)
Norway	14 (7%)	11 (7%)	11 (7%)
Philippines	1 (0%)	0 (0%)	0 (0%)
Poland	1 (0%)	1 (1%)	1 (1%)
Portugal	3 (1%)	2 (1%)	2 (2%)
South Africa	1 (0%)	1 (1%)	1 (1%)
Sweden	26 (13%)	18 (12%)	18 (14%)
Switzerland	4 (2%)	4 (3%)	3 (2%)
UK	28 (14%)	17 (12%)	12 (9%)
USA	20 (10%)	14 (10%)	13 (10%)
Zimbabwe	1 (0%)	1 (1%)	1 (1%)

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The proportion of participants in each stakeholder group that rated each outcome as “important” on the 5-point and 9-point rating scales in rounds 1 to 3 is presented in S2 Table and the findings of the face-to-face consensus meeting are presented in Table 4. The stakeholder ratings are presented in full detail in S2 Table and Table 4 so that the outcomes can be tracked throughout the whole consensus process so comparisons can be made for full transparency. After adjusting for consensus in round 3, 25 outcomes were taken forward for discussion and voting at the face-to-face consensus meeting (Table 4).

Table 4. Preliminary PGP-COS and consensus meeting voting results.

Domain	Outcome	Yes	No
Life impact outcomes (n = 20)	Pain frequency^*	8 (73%)	3 (27%)
Life impact outcomes (n = 20)	Pain intensity/severity^*	9 (82%)	2 (18%)
	Pain location	3 (27%)	8 (73%)
	Pain duration/pattern	3 (27%)	8 (73%)
	Function/disability/activity limitation^*	11 (100%)	0 (0%)
	Physical activity levels/exercise limitations	2 (18%)	9 (82%)
	Sexual functioning	3 (27%)	8 (73%)
	Health related quality of life^*	10 (91%)	1 (9%)
	Health status	1 (9%)	10 (91%)
	Family life impact	2 (18%)	9 (82%)
	Social life impact	2 (18%)	9 (82%)
	Patient satisfaction with life	2 (18%)	9 (82%)
	Patient satisfaction with treatment	2 (18%)	9 (82%)
	Anxiety	1 (9%)	10 (91%)
	Depression	0 (0%)	11 (100%)
	Emotional symptoms	1 (9%)	10 (91%)
	Fear avoidance^*	8 (73%)	3 (27%)
	Pain catastrophizing	3 (27%)	8 (73%)
	Self-efficacy	1 (9%)	10 (91%)
	Sleep function	4 (36%)	7 (64%)
Resource-use/Economic Impact Outcomes (n = 1)	Work ability	2 (18%)	9 (82%)
Pathophysiological Manifestations/ Clinical Tests Outcomes (n = 4)	Gait endurance	1 (9%)	10 (91%)
	Recovery of symptoms	3 (27%)	8 (73%)
	Urinary Incontinence	0 (0%)	11 (100%)
	Motor control/movement strategies/movement patterns	0 (0%)	11 (100%)

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* Outcome included in final PGP-COS.

Consensus meeting

Twenty-five participants were invited to take part in the face-to-face consensus meeting. Thirteen participants agreed to participate; however, due to last minute travel emergencies, the final number participating in the meeting was 11 stakeholders. Consensus meeting participant characteristics, including multiple stakeholder group affiliations, are provided in Table 5. The results of the voting are presented in Table 4. Five outcome measures, all of which are included in the ‘life impact’ domain, achieved consensus and constitute the agreed final PGP-COS. These outcomes are pain frequency, pain intensity/severity, function/disability/activity limitation, health related quality of life and fear avoidance.

Table 5. Consensus meeting participant characteristics.

Stakeholder Group Representative	n
Clinician	3
Clinician/researcher	4
Patient	1
Researcher	3
Service provider/policy maker	0
Multiple Stakeholder Group Affiliations	n
Patient/clinician	1
Patient/researcher	2
Patient/researcher/clinician	1
Patient/clinician/service provider	1
Clinician/service provider	1
Clinician/researcher/service provider	1
Gender	n
Female	10
Male	1
Age	n
25–34	2
35–44	4
45–54	2
55–64	3
Country of Residence	n
Australia	1
Belgium	1
Colombia	1
Ireland	2
Israel	1
New Zealand	1
Norway	2
Sweden	1
USA	1
Profession	n
Assistant Professor Musculoskeletal Rehabilitation	1
Chiropractor	1
Director of Research	1
Lecturer Physiotherapy	1
Manual therapist (Naprapath)	1
Manual therapist/physiotherapist	1
Physiotherapist	2
Physiotherapist/lecturer	1
Researcher/chiropractor	1
Unemployed due to PGP	1

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Discussion

This study provides a COS of five outcomes that should be reported in future PGP studies and in clinical practice. It fills an important gap in the literature, as there is currently no COS for pregnancy-related and postpartum-related PGP.

An interesting result of this study is that outcomes in the PGP-COS are “life impact” outcomes. This likely takes consideration of the symptomology of PGP, and can be aligned to the European Guidelines for the diagnosis and treatment of PGP which have a focused PGP treatment aim of relieving pain, improving functional ability and preventing recurrence and chronicity [26]. Additionally, one PGP-COS outcome in particular, fear avoidance, has been heavily studied in low back pain populations, but is not yet extensively studied in pregnancy and postpartum related PGP. Uptake of the PGP-COS will result in increased reporting of fear avoidance in this population and may offer a better understanding of its impact in PGP. Overall, the consensus panel members during discussion expressed that many of the outcomes presented in the preliminary PGP-COS were similar or often related and could be captured by the outcomes that were included in the final PGP-COS; in this sense, they considered the five PGP-COS outcomes as critical for measuring and reporting, while also sufficiently broad to effectively assess PGP treatment. Overall, due to its brevity, reporting the outcomes of the PGP-COS, we believe, can be readily assimilated into future research and clinical practice protocols.

Strengths and limitations

In conducting this study, a number of strengths and limitations are acknowledged. Robust consensus methodology was used to develop the PGP-COS [21]. Additionally, a detailed study protocol was published, prospectively, and the results of this study were presented using the COS-STAR statement guidance to ensure clarity and a high standard of reporting of the PGP-COS [18, 20, 21]. Finally, online Delphi methods were used to capture the views and expertise of an international, multidisciplinary and multi-stakeholder cohort, which also include patient representatives.

This study, however, is not without limitations. Although we sought international participation, our Delphi surveys were created only in English due to time and budgetary constraints. We did try to account for this by using Google Forms to host the surveys, as it provides an option to translate the survey into any language, supported by Google Translate, when viewing in a Google Chrome browser. However, Delphi participants using an alternative web browser would not have had this option. Although, it is plausible that English language surveys could have deterred initial Delphi participation or impacted retention from non-native English-speaking respondents between rounds. In addition to language barriers, lower than expected uptake in certain geographical regions may also be attributed to less awareness about the condition itself. While we did provide a definition for PGP in the PIL associated with our Delphi survey, differences in individual and provider knowledge and lack of access to services for PGP may have been associated with lower uptake in particular regions. Recognising these limitations, however, we did achieve excellent international representation in the Delphi study (32 countries) and in our consensus meeting (9 countries).

A further limitation to our study is participant representation at the consensus meeting. In our protocol, we had aimed to include 20 experts, and although 25 were invited, only 11 took part. While this is fewer than participant numbers reported in other COS development studies, it adheres to the recommendation of a consensus panel size of 5–11 as recommended by Waggoner and colleagues [27] Additionally, it is similar to previously reported COS development studies in which included a face-to-face consensus meeting [21, 28]. We also did not have equal representation of members from the various stakeholder groups; for example, there was no representation for the service provider/policy maker stakeholder group, as only eight Delphi participants met the eligibility criteria for the meeting and all declined to attend. Additionally, two patient representatives did not attend due to last minute travel emergencies. However, while panel members were invited as representatives of his/her primary stakeholder group affiliation, many identified with more than one stakeholder group, including the service provider/policy maker group (Table 5) In this sense, the voice of this group was present in determining the final PGP-COS. Finally, while lack of equal stakeholder group representation may contribute to bias, is important to note that there is currently no explicit guidelines on which stakeholder groups and how many should be present at the consensus meeting [21]. As a result, representation of the stakeholder groups that participated in the Delphi study present during these face-to-face meetings varies across previously developed COS [21] and in some instances, such as in the non-specific low back pain COS, the steering committee made the final decision in place of a face-to-face meeting with Delphi participants [29]. Further methodological research into COS development would assist in composing more explicit guidance.

Protocol deviation

In accordance with the COS-STAR statement, it is important to note a deviation from our protocol with regards to the prior consensus definition used in this study [20]. In our protocol, we defined our a priori consensus as outcomes scored by ≥70% of participants as “important” and less than 15% of participants scoring an outcome as “not important” [18]. This definition was initially chosen with the aim of 40 participants in each stakeholder group completing the Delphi study. However, after we closed the first round of the Delphi and before we began analysis, we changed our a priori consensus definition to ≥70% participants rating the outcome as “important” by three of the five stakeholder groups, one of which must have been the patient representative group, due to unequal representation in stakeholder group participation. This was decided so that stakeholder groups with more participants would not dominate the results in each Delphi round and that the “voice” of the patient representative group would always be included.

Future work

Now that a PGP-COS has been identified, future work is needed. In order to combine and compare outcomes across studies, the outcomes, ideally, should be measured in the same way; that is using the same instrument. The next phase of the PGP-COS study (Fig 1: Phase 4) aims to perform a robust systematic review of measurement properties on all measurement instruments used to measure the five COS outcomes [18]. This review is currently on-going using COSMIN (COnsensus-based Standards for the selection of health Measurement INstruments) for methodological guidance [30–32]. The results from this review will allow for evidence-based recommendations in the selection of the most suitable measurement instrument to be used for consistent measurement and reporting of the PGP-COS. Finally, efforts will be needed to promote and monitor the uptake of the PGP-COS. The final phase of the PGP-COS study (Fig 1: Phase 5) will involve global promotion of the COS. Details of our plan for global promotion are detailed in the protocol [18]. Promotion and use of the PGP-COS will encourage effective monitoring, increase trial efficiency, improve evidence synthesis and reduce research waste to speed up the development and testing of prevention and management strategies worldwide.

Conclusion

The evaluation of interventions for PGP in women during pregnancy and postpartum is difficult due to inconsistent outcome reporting. This is the first study to define a COS in this area which can be used in research and clinical settings. Uptake of the consensus-based PGP-COS in all trials, non-randomised studies and clinical settings will encourage consistent reporting, effective monitoring, increased trial efficacy, improved evidence synthesis and reduce research waste to speed up the development and testing of interventional strategies, ultimately resulting in the global promotion of the health and well-being of women with PGP worldwide. The next phase of the PGP-COS will determine how to measure the outcomes of the PGP-COS.

Supporting information

S1 Table. List of potential PGP-COS outcome measures.

(DOCX)

Click here for additional data file.^{(34KB, docx)}

S2 Table. Delphi results.

S2 Table details the % of stakeholder group that rated an outcome as “important” (4+ on the 5-point rating scale survey or 7+ on the 9-point rating scale survey) above in each Delphi round. ^± Outcome in final PGP-COS * Group 1 = clinician; 2 = clinician/researcher; 3 = patient; 4 = researcher; 5 = Service provider/policy maker ^a 5PT = participants responded to Delphi surveys using a 5-point rating Scale ^b 9PT = participants responded to Delphi surveys using a 9-point rating Scale.

(DOCX)

Click here for additional data file.^{(111KB, docx)}

Acknowledgments

We would like to thank all participants of our Delphi study and consensus meeting for dedicating their time to help develop the PGP-COS.

We would like to acknowledge consensus meeting members Adi Amit David, Anne Randi Høidahl, Daniela Aldabe, Dragana Ceprnja, Gabriel Quintero, Katherine A Pohlman, Lotte Janssens, Miriam Gamble, Natalie Michelle Evensen, and Stine Lilje.

Data Availability

All relevant data are within the manuscript and its Supporting information files.

Funding Statement

We have received funding from the Belgian Chiropractic Union Research Fund (www.chiropraxie.org) and from the European Centre for Chiropractic Research Excellence (nikkb.dk/eccre). The funders had no role in the study design, data collection, management, data interpretation, report writing and decision to submit for publication.

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PLoS One. doi: 10.1371/journal.pone.0247466.r001

Decision Letter 0

Kathleen Finlayson

28 Sep 2020

PONE-D-20-18595

A Core Outcome Set for Research and Clinical Practice in Women with Pelvic Girdle Pain: PGP-COS

PLOS ONE

Dear Dr. Remus,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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==============================

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: I Don't Know

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: The paper presents results of a Delphi study to establish a Core Outcome Set (COS) for pelvic girdle pain (PGP) in pregnancy and postpartum. There is a lack of standardization in studies on PGP, especially related to the outcome measures selected for use with the pregnant and postpartum population with PGP. This lack of standardization results in disparate results across studies on the population of interest, and consequently, impedes the synthesis and broader analysis of research on PGP in pregnant and postpartum women. This paper has performed a 3-round Delphi study with an in-person consensus meeting involving multiple stakeholders across several countries. Five outcomes were selected by the Delphi group as the proposed PGP-COS: pain frequency, pain intensity/severity, function/disability/activity limitation, health-related quality of life and fear avoidance.

The rationale, methodology, results and implications of the study are presented clearly and logically. The five outcomes selected for the PGP-COS are logical, clinically relevant, feasible and not duplicative. While the constructs for each outcome are related, the overlap is not excessive and is, in fact, complementary when considering the client with PGP as a whole. All refer to the “life impact” domain, rather than outcomes that focus on specific physical impairments, such as muscle strength, flexibility or joint symmetry. This supports the clinical relevance and feasibility of moving forward with the proposed PGP-COS in clinical practice and research. Inclusion of, and further research on, the proposed PGP-COS from an implementation standpoint would add to the current literature on PGP, as the “life impact” of PGP on childbearing women (on a national or global) level is limited.

One of the biggest challenges in PGP research is the construct of patients’ own expectations of pain during pregnancy and their perceptions of “normal” recovery during the postpartum. While the authors described the online survey process of the first round of the Delphi study, several elements that speak to the constructs of pain, specifically PGP, women’s own expectations, and the cultural aspects of both pain and what is considered “normal” expectations of musculoskeletal pain and functional status in pregnancy and postpartum across countries were not clearly described. This is the biggest challenge to address in this manuscript, as it appears that assumptions may have been made about stakeholders’ shared understanding of PGP and the impact of cultural differences. While the ranking process addressed stakeholders’ shared value of importance for each outcome, it does not address cultural differences or stakeholders’ expectations. These differences or discrepancies in stakeholders’ shared understanding of PGP, expectations and cultural differences may contribute biases to the results of the Delphi study.

The presence and targeted inclusion of international stakeholders is a strength of this Delphi study. The authors have addressed study limitations of using English only survey tools and having fewer participants than projected involved the final in-person consensus meeting. Additional sources of potential bias and limitations in the generalizability of the proposed PGP-COS, as a result, should be considered. Participants were predominantly: clinicians and clinical researchers, female, middle age, and from Ireland, Sweden, USA and Canada. Information on countries’ maternal health systems, specifically public and health provider knowledge of PGP, as well as reimbursement and access to physiotherapy services for PGP in pregnancy and postpartum, may identify important characteristics of stakeholder countries who responded to the Delphi survey compared to those who did not. A narrative of the authors’ perspectives on the characteristics of participants and how those characteristics are representative of the larger community of interest would add to the manuscript.

The link proposed between development of the PGP-COS and evaluating “preventative” strategies for PGP during pregnancy and postpartum is unclear. The PGP-COS will measure “life impact” of PGP, in patients who have already or are currently experiencing PGP in pregnancy or postpartum. Additional description of the link between use of the PGP-COS and preventative strategies is needed.

Reviewer #2: This manuscript describes a diligently methodical process of identifying a well-vetted core outcome set for prenatal and postpartum pelvic girdle pain. I found the manuscript to be well written and to describe a clinically sound process.

One improvement that could be made would be references in the introduction to specific ways in which lack of a COS for PGP has impacted the literature on this problem. For those of us who do not regularly evaluate or manage PGP, this might be helpful.

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Reviewer #1: Yes: Adrienne H. Simonds, PT, PhD

Reviewer #2: No

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PLoS One. 2021 Feb 25;16(2):e0247466. doi: 10.1371/journal.pone.0247466.r002

Author response to Decision Letter 0

28 Oct 2020

Thank you for your thorough summary and complementary words about our manuscript. We have addressed your comments as below.

Thank you for a concise summary of our manuscript.

Thank you for your comments. We agree that implementation and uptake of the proposed PGP-COS will add to the current literature on PGP as the “life impact” of PGP on childbearing women is limited.

Thank you for your comment. We acknowledge that there are country and cultural differences regarding expectations of pain during pregnancy and perceptions of “normal” recovery during the postpartum and note that there are individual differences as well. For example, two patients can have different expectations about recovery from pregnancy related PGP. However, in this phase of our overall study, the objective focus was on ‘what to measure’ rather than ‘how’ to measure, or on variations as a result of country or cultural differences. These aspects may emerge in phase 4 of the project where the focus is on ‘how’ to measure the COS outcomes, and in the context of future individual trials/studies where this COS (hopefully) will be used. We are thus confident, while accepting the important point you raise, that this does not bias the Delphi results, but will have a role in the application of the PGP-COS; a point we will attend to in reporting phase 4 of the project (‘how’ to measure the outcomes in the COS).

Thank you for raising this point. We agree that only language and fewer participants than expected in the consensus meeting are not the only limitations in larger uptake from different nations. Additionally, partial reasons for less uptake in some countries can also be attributed to less awareness about the condition both at individual and healthcare system levels. This is reflective of provider knowledge and access to services. We have addressed this as a further limitation to our study in our manuscript.

Thank you. For clarity we have removed references to “preventative strategies” and refer now to a COS for interventions for PGP. We have slightly tweaked the ‘Aim’ also to clarify this further, which now reads; The aim of our study was to develop a consensus-based COS for PGP during pregnancy and postpartum that should be used, as a minimum, for research and clinical practice.

Thank you for your time in reviewing our manuscript. We have added specific comments to the introduction (paragraph 1) in which the lack of a PGP COS has impacted the literature for clarity to those who do not regularly evaluate or manage PGP.

Attachment

Submitted filename: Response to Reviewers.docx

Click here for additional data file.^{(35.6KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0247466.r003

Decision Letter 1

Kathleen Finlayson

15 Dec 2020

PONE-D-20-18595R1

A Core Outcome Set for Research and Clinical Practice in Women with Pelvic Girdle Pain: PGP-COS

PLOS ONE

Dear Dr. Remus,

Thank you for addressing the reviewers' comments. Please see and consider further reviewer suggestions below, in particular, including "comparison of the round 3 stakeholders' response, or reporting round 3 results and presenting how they compare to the final 11 participants' consensus opinions", to address the issue discussed.

Please submit your revised manuscript by Jan 29 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Kathleen Finlayson

Academic Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Yes

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: N/A

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4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #1: Yes

Reviewer #2: Yes

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #1: Yes

Reviewer #2: Yes

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6. Review Comments to the Author

Reviewer #1: The authors have addressed prior feedback early on in the paper well. Minor edits are suggested below.

Inconsistencies noted in the organization of preliminary outcomes (Table 1), with some lack of clarity on the transition between rounds.

1. The "Pathophysiological Manifestations" title in column 3 may also include aspects of pain, depression and anxiety, sleep disturbance, emotional symptoms, confidence and wellbeing, etc. These outcomes are already listed in "Life Impact". There appears to be some redundancy across those 2 columns, and in categorizing outcomes, the authors might consider including "Pathophysiological Manifestations" into "Life Impact" and leave the clinical tests in this freestanding category.

2. The outcomes included in the third column - "Pathophysiological Manifestations/Clinical Tests" of maternal pregnancy outcome, newborn outcome and surgical outcome do not seem to be appropriately categorized. Perhaps these should move to "Adverse Events and/or Medical Outcomes" to capture these factors, or be assigned a stand-alone column for Medical Outcomes.

3. The "anthropometric outcome" is unclear - does this refer to weight gain and/or BMI during pregnancy?

4. "Recovery of symptoms" seems too broad. This may then include "full pain recovery" which is listed in "Life Impact". These categories should be mutually exclusive, meaning that outcomes listed across may be related, but cannot be interchanged for each other. Perhaps some recoding of categories and/or re-evaluation of outcomes is needed.

Rating scales used to assess preliminary outcomes in Round 1 and 2 of the Delphi study include both a 5-point and a 9-point scale, administered randomly. Explanation of the rationale for use of the 2 different scales is suggested. Although it is mentioned this will be presented in a separate paper, it is a point of confusion for this study's methodology.

The limitations of the consensus meeting are again, striking. To base the final round of inclusion on the opinions of 11 individuals, when 132 stakeholders completed round 3, seems potentially biased. This final consensus round, arguably the most important and most impactful round on results of this Delphi study, represented the opinions of only 17% of the stakeholders. While this limitation is explained because of travel emergencies, it is suggested the authors perform additional statistical analyses on the results of round 3 and/or explore a remote voting process for the 83% of round 3 stakeholders whose voices and opinions were not heard in this final round of the Delphi process. Perhaps a comparison of the round 3 stakeholders' response, or a virtual consensus meeting may be needed, or reporting round 3 results and presenting how they compare to the final 11 participants' consensus opinions.

Additionally, of the 11 participants at the consensus meeting, 6 (54.5%) were researchers. This also contributes to bias. While the authors disclose participants at the consensus meeting holding multiple roles, this point should be made explicit.

Reviewer #2: My concerns were limited and have been satisfactorily addressed. I have not other concerns at that this time.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: Yes: Adrienne H. Simonds, PT, PhD

Reviewer #2: No

PLoS One. 2021 Feb 25;16(2):e0247466. doi: 10.1371/journal.pone.0247466.r004

Author response to Decision Letter 1

29 Jan 2021

Dear Editor and Reviewers,

Thank you for your helpful comments on our revised paper. We have attended to the comments with point by point responses as below, and in further revisions to the manuscript. We hope these meet the requirements for progressing our paper to publication.

Editor:

Thank you. We have addressed this comment of reviewer 1 below. While direct statistical comparison of round 3 responses with the results of the consensus meeting was not conducted since it was not feasible nor appropriate (see reasons in response to reviewer’s comment), readers can easily compare the round 3 and consensus meeting results from the information provided in table 4 and supplementary table 2. This is now also mentioned in the manuscript.

Reviewer #1: The authors have addressed prior feedback early on in the paper well. Minor edits are suggested below.

Inconsistencies noted in the organization of preliminary outcomes (Table 1), with some lack of clarity on the transition between rounds.

Thank you for your comment. Our outcome categorisation and subsequent table headings adhere to the OMERACT 2.0 Filter Framework (Boers et al. 2014). In this framework Life Impact and Pathophysiological Manifestations are established as separate domains. According to this framework, aspects of pain, depression and anxiety, sleep disturbance, emotional symptoms, confidence and wellbeing, etc. are classified as Life Impact domain outcomes (Fig 1; Boers et al 2014). We have kept Table 1 column titles as is for consistency with this framework and also the previous publication in which possible outcomes for the PGP-COS were identified (Wuytack and O’Donovan. 2019).

Thank you for your comment. As described above, the outcomes are categorised according to the OMERACT 2.0 filter framework (Boers et al. 2014) and our previous publication identifying potential outcomes for the Delphi study (Wuytack and O’Donovan. 2019). We have kept categorisation as is for consistency as well as the outcomes were grouped as such during the Delphi Study. We have included a statement addressing this in the main text (page 6).

3. The "anthropometric outcome" is unclear - does this refer to weight gain and/or BMI during pregnancy?

Thank you for your comment. Anthropometric outcomes were identified in our previous systematic review (Wuytack and O’Donovan. 2019) as well as in Supplementary Table 1 of this manuscript. Anthropometric outcomes were defined as measurements of size and proportion of the human body for example, height, weight, BMI, etc.. Reference to S1 Table is made in the Delphi Procedure section of methods. It is not referenced in Table 1 as this is just a list of the potential outcomes.

Thank you comment. Full pain recovery in our Delphi survey was defined as “being pain free/no longer in pain after treatment.” This is separate to recovery of symptoms as symptoms can include more than pain. The definition is also included in Supplementary Table 1. As mentioned above we have kept categorisation as is for consistency across publications as well as this is how outcomes were identified in studies included the systematic review leading into the Delphi (Wuytack & O’Donovan 2019) and were presented to participants during the Delphi Study.

Thank you for your comment. We have added an explanation of our rational for using the two scales in the main text. The findings from the embedded methodological study have since been published and we have addressed the text appropriately for reader’s reference (page 9).

Thank you for your comment. We understand your concern regarding 11 participants in our face-to-face consensus meeting. However, we adhered to the current methodological guidelines for Core Outcome Set development developed by COMET (Core Outcome Measures in Effectiveness Trials Initiative). According to these guidelines, the face-to-face consensus meeting includes a subset of participants. These guidelines do not include a required number of participants. However, Waggoner, Carline and Durning. 2016 have previously explored the optimal consensus panel size and have determined 5-11 members is recommended. We had referenced this in our limitations but since realised that the article was incorrectly referenced. This has been rectified and is now included in our reference list. In line with these recommendations, most other previous COS development projects use a similar size sub-group of Delphi participants for the face-to-face. It is also important to note that while the COMET handbook does recommend a face-to-face meeting, they also refer to a review that identified that not all COS include this step in their development (page 24 of the handbook). While the face-to-face meeting may seem to be the most important and most impactful round, the three previous rounds of the Delphi study are just as important. The Delphi process is a consensus process itself.

In our Supplemental Table 2 (S2 Table) we have provided how all stakeholder groups voted throughout all rounds and have also highlighted the final five outcomes included in the PGP-COS. From this table, comparisons between the consensus meeting and round 3 responses can be made. However, statistical comparison of round 3 responses with the results of the consensus meeting was not feasible nor appropriate due to the following reasons: 1) This is not recommended in current COS development methodology (COMET handbook); 2) The consensus definition in the Delphi and face-to-face meeting were different in that for the Delphi >70% of only 3 stakeholder groups (including at least the patient group) needed to rate an outcome as important, while for the meeting >70% of all participants had to vote an outcome as important (This is line with current COS development guidelines; 3) The 2 different scales we used makes for the embedded methodological study. For example 6 outcomes that were voted on in the consensus meeting were only voted on by one of the scale groups (not both).

Some outcomes that were rated high by all stakeholder groups in Round 3 were not subsequently included in the final COS during the face-to-face consensus meeting. However, this is expected during the consensus process aiming at identifying a small number of core outcomes that should and could be measured in all trials and in clinical practice. As more and more rounds are incorporated during the whole consensus process, more and more outcomes begin to not reach consensus. This is evidenced by starting with 53 outcomes in Round 1 to only 20 outcomes reaching consensus in round 3. It is therefore expected that the number of outcomes reaching consensus in round 3 would reduce during the final face-to-face meeting. Several outcomes from round 3 (e.g. sexual functioning) were also not included in the final COS because it was agreed by the participants that they formed part of other outcomes that were included in the final COS (e.g. activity limitations) (this is mentioned in the discussion on page 16). Finally, it is also important to note that only 13% of Delphi participants expressed interest in participating in the face-to-face consensus meeting when asked at completion of the survey (being informed that travel and accomodation costs would be funded). As such, it would not be feasible or methodologically appropriate to include all participants from round 3 in the face-to-face consensus meeting.

Thank you for your comment. Table 5 reports that 3 participants were researchers, 3 participants were clinicians and 4 participants were clinician/researchers. While having a larger number of researchers may contribute to bias, there is currently no consensus on who should be involved in the face-to-face meeting (COMET Handbook). Table 5 also reports the multiple roles by the 11 participants (including participants who were patients in addition to belonging to other stakeholder group(s)). We have addressed the text to be more explicit about the multiple roles of these participants (page 14 and 18).

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PLoS One. doi: 10.1371/journal.pone.0247466.r005

Decision Letter 2

Kathleen Finlayson

8 Feb 2021

A Core Outcome Set for Research and Clinical Practice in Women with Pelvic Girdle Pain: PGP-COS

PONE-D-20-18595R2

Dear Dr. Remus,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Additional Editor Comments (optional):

Thank you for addressing the reviewers' comments and clarifying the queries on methods.

Please consider adding an edit to address the query about 'anthropometric outcome' definition in Table 1 - (e.g. add BMI in brackets?, or the reference)

Reviewers' comments:

PLoS One. doi: 10.1371/journal.pone.0247466.r006

Acceptance letter

Kathleen Finlayson

16 Feb 2021

PONE-D-20-18595R2

A Core Outcome Set for Research and Clinical Practice in Women with Pelvic Girdle Pain: PGP-COS

Dear Dr. Remus:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

S1 Table. List of potential PGP-COS outcome measures.

(DOCX)

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S2 Table. Delphi results.

(DOCX)

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Data Availability Statement

All relevant data are within the manuscript and its Supporting information files.

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PERMALINK

A core outcome set for research and clinical practice in women with pelvic girdle pain: PGP-COS

Alexandria Remus

Valerie Smith

Annelie Gutke

Juan Jose Saldaña Mena

Siv Mørkved

Lena Nilsson Wikmar

Birgitta Öberg

Christina Olsson

Hilde Stendal Robinson

Britt Stuge

Francesca Wuytack

Roles

Abstract

Background

Methods

Results

Conclusion

Core outcome set registration

Introduction

Methods

Fig 1. PGP-COS study phases.

Phase 1: Preliminary list of outcome measures

Table 1. Preliminary outcomes.

Phase 2: An international Delphi study

Participant selection and recruitment

Delphi procedure

Table 2. Rating scales.

Consensus meeting

Results

Delphi study

Table 3. Delphi study participant characteristics.

Table 4. Preliminary PGP-COS and consensus meeting voting results.

Consensus meeting

Table 5. Consensus meeting participant characteristics.

Discussion

Strengths and limitations

Protocol deviation

Future work

Conclusion

Supporting information

Acknowledgments

Data Availability

Funding Statement

References

Decision Letter 0

Kathleen Finlayson

Roles

Author response to Decision Letter 0

Decision Letter 1

Kathleen Finlayson

Roles

Author response to Decision Letter 1

Decision Letter 2

Kathleen Finlayson

Roles

Acceptance letter

Kathleen Finlayson

Roles

Associated Data

Supplementary Materials

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

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