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Abstract
Objective To provide an overview of barriers and facilitators that healthcare professionals (HCPs) perceive regarding the implementation of lifestyle interventions (LIs) in patients with hip and/or knee osteoarthritis (OA).
Design Scoping review.
Data sources The databases PubMed, Embase, CINAHL, PsycINFO and the Cochrane Library were searched from inception up to January 2021.
Eligibility criteria Primary research articles with a quantitative, qualitative or mixed-methods design were eligible for inclusion if they reported: (1) perceptions of primary and/or secondary HCPs (population); (2) on implementing LIs with physical activity and/or weight management as key components (concept) and (3) on conservative management of hip and/or knee OA (context). Articles not published in English, German or Dutch were excluded.
Data extraction and synthesis Barriers and facilitators were extracted by two researchers independently. Subsequently, the extracted factors were linked to a framework based on the Tailored Implementation for Chronic Diseases checklist.
Results Thirty-six articles were included. In total, 809 factors were extracted and subdivided into nine domains. The extracted barriers were mostly related to non-optimal interdisciplinary collaboration, patients’ negative attitude towards LIs, patients’ low health literacy and HCPs’ lack of knowledge and skills around LIs or promoting behavioural change. The extracted facilitators were mostly related to good interdisciplinary collaboration, a positive perception of HCPs’ own role in implementing LIs, the content or structure of LIs and HCPs’ positive attitude towards LIs.
Conclusions Multiple individual and environmental factors influence the implementation of LIs by HCPs in patients with hip and/or knee OA. The resulting overview of barriers and facilitators can guide future research on the implementation of LIs within OA care. To investigate whether factor frequency is related to the relevance of each domain, further research should assess the relative importance of the identified factors involving all relevant disciplines of primary and secondary HCPs.
PROSPERO registration number CRD42019129348.
- orthopaedic & trauma surgery
- hip
- knee
- musculoskeletal disorders
- rehabilitation medicine
- sports medicine
Data availability statement
Data sharing not applicable as no datasets generated and/or analysed for this study.
This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.
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Strengths and limitations of this study
To our knowledge, this is the first scoping review to classify barriers and facilitators for implementing lifestyle interventions by healthcare professionals as conservative treatment for hip and/or knee osteoarthritis in which qualitative and quantitative data were combined.
The study population consisted of all primary and secondary healthcare professionals involved in hip and/or knee osteoarthritis care.
Given the broad definition of ‘implementing lifestyle interventions’, the identified barriers and facilitators provide insight into the full spectrum of influencing factors rather than being applicable to every single way of implementing lifestyle interventions.
Grey literature was not included in the search and selection process.
Introduction
Regular physical activity and weight management are recommended by national and international clinical guidelines for the conservative management of hip and/or knee osteoarthritis (OA).1–5 Previous studies have demonstrated that lifestyle interventions (LIs) focusing on exercise, alone or combined with dietary weight loss, are able to reduce hip and/or knee OA-related disability and to postpone or even prevent total joint arthroplasty.6–10 However, these positive results are not always transferred from research settings to daily practice, which means that LIs are underused.11 This suboptimal implementation of LIs as treatment for hip and/or knee OA can result from factors related to the patient, the healthcare professional (HCP) or the societal context.12 Research on adhering to LIs has so far focused mainly on identifying barriers and facilitators at the patient level. However, these studies have also shown that HCPs can have a facilitating role in the lifestyle behaviour of their patients, for example by providing advice, education, encouragement and instructions.13 14
Some research has already been conducted investigating the perspective of HCPs and the implementation of LIs in their daily practice. This knowledge is needed in order to enhance the implementation of LIs. As far as the authors know, no (systematic) literature review has previously been performed that identified and/or classified barriers and facilitators for implementing LIs in the conservative treatment of hip and/or knee OA from the perspective of all HCPs involved. One systematic review focused on the views towards OA management based on recommendations in clinical practice guidelines of HCPs working in primary care.15 However, HCPs working in secondary care are also involved in the treatment of patients with OA, which draws attention to the importance of collaboration and communication between primary and secondary care practitioners.16 Therefore, a scoping review was conducted aiming to provide a comprehensive overview of barriers and facilitators perceived by primary and secondary HCPs regarding the implementation of LIs in patients with hip and/or knee OA. The Tailored Implementation for Chronic Diseases (TICD) checklist was used to guide data synthesis.17 Within the context of this review, implementation was defined as the use of LIs as conservative treatment for hip and/or knee OA by individual HCPs.
Method
Study design
A scoping review has been defined as follows by Colquhoun et al: ‘a form of knowledge synthesis that addresses an exploratory research question aimed at mapping key concepts, types of evidence and gaps in research related to a defined area or field by systematically searching, selecting and synthesising existing knowledge’.18 Therefore, a scoping review was considered a suitable methodology to summarise existing literature on barriers and facilitators for implementing LIs in hip and/or knee OA and to identify potential gaps in the current literature on participation of primary and secondary HCPs. We conducted this scoping review according to the framework developed by Arksey and O’Malley.19 Five stages were followed successively: (1) identifying the research question; (2) identifying relevant studies; (3) study selection; (4) charting the data and (5) collating, summarising and reporting the results.19 The Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews checklist was used as reporting guideline.20
Data sources and searches
A search strategy was developed consisting of four components: search terms related to: (1) primary and secondary HCPs; (2) hip and/or knee OA; (3) LIs and (4) barriers and facilitators. This search strategy was applied in five bibliographic electronic databases (ie, PubMed, Embase, CINAHL, PsycINFO and the Cochrane Library) to identify relevant articles from inception up to 19 January 2021. A detailed search strategy for each of the databases can be found in online supplemental file 1. Reference lists of included articles were manually searched for additional relevant articles. Primary research articles with a quantitative, qualitative or mixed-methods design were eligible for inclusion; study protocols, reviews, abstracts and commentaries were excluded. Articles written in English, German or Dutch were eligible for inclusion. No restrictions were applied regarding publication period.
Supplemental material
Study selection
Eligibility criteria were described according to the population–concept–context framework.21 First, the study population was defined as all primary and secondary HCPs who are involved in the conservative treatment of patients with hip and/or knee OA. This definition includes, respectively, HCPs providing general medical care and HCPs providing more specialised care (with or without a referral). Articles focusing solely on the perspective of patients with hip and/or knee OA were excluded. Second, the concepts central to this review were barriers and facilitators for implementing LIs. Barriers and facilitators were defined as any belief, experience, factor, opinion, reason or view reported by an HCP that potentially influences (either impedes or facilitates) implementation of LIs in patients with hip and/or knee OA. These barriers and facilitators were extracted from both quantitative (eg, survey) and qualitative (eg, interview) data. Implementing LIs was broadly defined, ranging from mentioning or discussing a healthy lifestyle to recommending or running specific lifestyle programmes, as long as it was clearly described that physical activity and/or weight management were key components. This definition includes physiotherapeutic exercise interventions (aerobic, functional or strengthening programmes), dietary interventions and self-management programmes. Physiotherapeutic modalities such as acupuncture, manual therapy, and massage, and self-management programmes whose content was not specified were not considered LIs and were therefore excluded. Physical activity was also broadly defined, ranging from physical activity during activities of daily living to participation in supervised or non-supervised exercise therapy or sports. Articles not primarily focusing on implementing LIs (eg, development and evaluation of clinical guidelines, general management of hip and/or knee OA, general patient–practitioner relationship or shared decision making) also fell outside the scope of this review. Lastly, the context of this review was the conservative treatment of hip and/or knee OA in both primary and secondary healthcare settings. Articles focusing on preoperative or postoperative treatment of hip and/or knee OA were excluded. Two researchers (SB together with AJ or JvB) independently assessed the eligibility of the identified articles based on the above criteria in three consecutive rounds: (1) based on title; (2) abstract and (3) full text of the article. Any disagreements among the researchers were resolved in consensus meetings.
Data extraction and quality assessment
A data extraction form was created and pilot-tested in order to systematically record study characteristics (first author, year of publication, country of origin, aims/purpose, study design, data collection method, data analysis method, theoretical basis, study population, setting, recruitment method, type of LI, patient population) and outcomes (barriers, facilitators and/or unclear factors (ie, an influencing factor, but not clearly defined as barrier or facilitator)). Study quality was assessed with the Mixed Methods Appraisal Tool (MMAT). The MMAT is a critical appraisal tool that can be used in reviews of mixed studies to assess the methodological quality of different study design categories: mixed-methods, qualitative and quantitative studies (randomised controlled trials, non-randomised studies and descriptive studies).22 23 Since calculating a total score is discouraged,23 it was chosen to present the ratings of the individual criteria.
Data extraction was performed in two stages. The first stage consisted of filling in the data extraction form and the MMAT for each article, done by two researchers (SB/JvB) independently. Regarding barriers and facilitators, both researchers extracted the relevant units of text and/or descriptive statistics from the Results sections. Any discrepancies between the researchers in this first stage were resolved in consensus meetings. During the second stage, the extraction of barriers and facilitators was discussed among the research team (SB/MS/IvdA-S) and the process was further refined for both quantitative and qualitative data. Regarding quantitative data, factors were only extracted if ≥50% of participants indicated that the factor influenced the implementation of LIs.24 25 For close-ended questions or attitude statements with multiple answer options, participants were classified as being ‘in agreement’ or ‘not in agreement’. If this classification had not yet been made by the authors of the original article, it was made based on the possible answer options, with ‘(strongly) agree’, ‘to a reasonable/large extent’ and ‘yes’ indicating agreement, and ‘neither disagree or agree’, ‘don’t know’, ‘neutral’, ‘a little bit/not at all’, ‘(strongly) disagree’, and ‘no’ indicating not in agreement. Next, the factor was classified as barrier or facilitator depending on the formulation of the question and which of the two groups (‘in agreement’ vs ‘not in agreement’) comprised ≥50% of the participants. In case of open-ended questions, all mentioned factors were extracted. Regarding qualitative data, if the authors of the original study did not explicitly identify a factor as barrier or facilitator, the description in the text or the participants’ quotes were used to classify the factor as barrier (ie, impeding/negative/problem/lack), facilitator (ie, facilitating/positive/solution/need) or unclear (ie, insufficient information). In addition, all unclear factors were rediscussed with a third researcher (IvdA-S) to assess whether these factors could nevertheless be classified as barrier or facilitator. At the end of the second stage, final data extraction based on the above criteria was performed by one researcher (SB), who also checked the consistency of the entire data extraction process.
Data synthesis and analysis
A narrative synthesis of the data was undertaken, based on the TICD checklist developed by Flottorp et al.17 This checklist aims to assist in identifying key determinants of professional practice, defined as factors that might prevent or enable healthcare improvements, and is intended for use in research on implementation and quality improvement in healthcare. It consists of seven domains: (1) guideline factors; (2) individual health professional factors; (3) patient factors; (4) professional interactions; (5) incentives and resources; (6) capacity for organisational change; and (7) social, political and legal factors. The authors of the current study have previously used the TICD checklist in the analysis of focus group data on the same topic, revealing two additional domains: (8) patient and HCP interactions; and (9) disease factors.26 One researcher (SB) assigned all extracted factors to one of these nine domains and then inductively developed different categories and subcategories of factors per domain. The resulting classification of factors and corresponding conclusions were subsequently discussed among the research team (SB/MS/IvdA-S).
Patient and public involvement
Patients or the public were not involved in this study as the study aim did not concern patients but HCPs.
Results
Study selection
A flow chart of the study selection process is presented in figure 1. A total of 8338 articles were retrieved. After removal of duplicates and exclusion of articles based on title or abstract, 93 potentially relevant articles remained for full-text screening. Ultimately, 36 articles were included in the qualitative synthesis.27–62
Flow chart of the study selection process.
Study characteristics
General characteristics of the included studies are presented in table 1. The majority of studies were conducted in Australia (36%), the Netherlands (19%), the UK (19%) and Canada (11%). Qualitative data were extracted in 26 studies (72%), quantitative data in 7 studies (19%), and both qualitative and quantitative data in the remaining 3 studies (8%). Individual interviews were most commonly used as qualitative data collection method, while the quantitative studies were all based on cross-sectional surveys. Most studies included physiotherapists or general practitioners (or physicians) as study population. Other participants were dieticians, exercise professionals, a nurse practitioner, an occupational therapist, orthopaedic surgeons, practice nurses, programme instructors, rheumatologists, telephone coaches and triaging clinicians.
Overview of included studies
Quality assessment
Findings of the quality assessment of the included studies based on the MMAT are shown in online supplemental file 2. Regarding the qualitative data assessments, only one study had the maximum of five positive ratings. Seven studies had a negative rating for the item on substantiating the interpretation of results, as no or a limited number of participant quotes were presented. In addition, many unknown ratings were given due to a lack of information about the applied qualitative approach and/or data analysis methods and their rationale. Regarding the quantitative data assessments, most studies had a negative or unknown rating for the risk of non-response bias due to low response rates or a lack of information about the response rate and/or reasons for non-response. In addition, the item on representativeness of the sample was often given an unknown rating because insufficient information about the sample and/or non-responders was presented. Finally, all three mixed-methods studies had a negative rating since the qualitative and quantitative components did not adhere to their specific quality criteria. For the other four mixed-methods criteria, only one of these three studies obtained positive ratings.
Supplemental material
Synthesis of results
A total of 809 factors were extracted from the 36 included articles. Table 2 presents the distribution of factors from the individual studies across the aforementioned nine domains, which were largely based on the TICD checklist. The highest number of factors was assigned to intervention factors (n=315), followed by individual HCP factors (n=144), and patient factors (n=137). The lowest number of factors was assigned to capacity for organisational change (n=7), followed by social, political and legal factors (n=9), and patient and HCP interactions (n=19). In table 3, the content of the nine domains is further explained by presenting an overview of the created categories and subcategories of factors that potentially influence the implementation of LIs by HCPs within each domain. A full overview of all extracted factors can be found in online supplemental file 3 (presented per domain) and online supplemental file 4 (presented per article).
Supplemental material
Supplemental material
Distribution of the extracted factors per included article across the domains, which were largely based on the Tailored Implementation for Chronic Diseases checklist
Overview of barriers, facilitators and unclear factors that influence the implementation of LIs as perceived by HCPs for all domains, which were largely based on the Tailored Implementation for Chronic Diseases checklist*
Categories
The distribution of barriers and facilitators across the various categories is presented in figure 2. The highest number of barriers was assigned to the following five categories: telehealth (n=40), collaboration (n=32), expertise (n=32), accessibility (n=32) and treatment expectations and preferences (n=31). The highest number of facilitators was assigned to the following five categories: telehealth (n=60), collaboration (n=46), design (n=45), effectiveness (n=41) and role (n=28).
Overview of the number of barriers and facilitators per category. The domain numbers indicated in brackets refer to the domains as presented in table 3: (1) intervention factors; (2) individual HCP factors; (3) patient factors; (4) professional interactions; (5) incentives and resources; (6) capacity for organisational change; (7) social, political and legal factors; (8) patient and HCP interactions and (9) disease factors. Unclear factors were not included in this figure due to the low number (n=11).
Subcategories
Tables 4 and 5 present the rankings of the ten largest subcategories of barriers and facilitators respectively. The first place in both rankings was assigned to a subcategory related to interdisciplinary collaboration or healthcare provision.
Ranking of the ten largest subcategories of barriers
Ranking of the ten largest subcategories of facilitators
Discussion
The aim of this review was to provide an overview of barriers and facilitators that primary and secondary HCPs perceive for implementing LIs in patients with hip and/or knee OA. By linking the identified factors to a framework that was largely based on the TICD checklist,17 a comprehensive overview of influencing factors was created that could serve as a basis for improving the implementation of LIs within primary and secondary OA care. The variety of domains shows that multiple levels (ie, both the level of the individual HCP and several environmental levels) should be considered in order to achieve this. Within this framework, the extracted barriers were most frequently related to non-optimal interdisciplinary collaboration, a negative attitude of patients towards LIs, low health literacy of patients, and a lack of knowledge and skills of HCPs around LIs or promoting behavioural change. The extracted facilitators were most frequently related to good interdisciplinary collaboration, a positive perception of HCPs’ own role in implementing LIs, the content or structure of LIs, and a positive attitude of HCPs towards LIs.
A relatively large number of studies were included, a majority of which was published in recent years. From these 36 studies, a total of 809 influencing factors were extracted. Although all nine domains were covered, the total number of factors identified within each domain differed greatly, ranging from 7 (capacity for organisational change) to 315 (intervention factors). In addition, a large variation was found in the number of barriers and facilitators between the various categories and subcategories. However, we do not know yet whether the established factor frequency is directly related to the importance of the domain, category or subcategory in question. So the fact that we found the highest number of factors within certain domains, categories or subcategories does not necessarily mean that these are the most important or relevant in the context of implementation. It could also be an indication that studies to date have mainly focused on these aspects, and that the others are still underexposed in the available literature. Therefore, we recommend to take all domains into account in future research in order to avoid missing factors that might be highly relevant for the implementation of LIs. The quality assessment of the included studies showed many unknown ratings due to a lack of information about, for example, the applied methods and their rationale. This finding does not have to mean that the studies are of low quality, but it does emphasise the importance of accurate and complete reporting of research using design-specific reporting guidelines.
Our results reflect those of a previous systematic review conducted by Egerton et al,15 in which the authors synthesised qualitative evidence only on primary care clinicians’ views on providing recommended management of OA up to August 2016. In addition to exercise and weight loss, recommended management included education, self-management support, and medication. The authors identified four barriers as main themes (1): ‘OA is not that serious’; (2) ‘clinicians are, or perceive they are, underprepared’; (3) ‘personal beliefs at odds with providing recommended practice’ and (4) ‘dissonant patient expectations’. A few system-related factors (eg, time, payment system) were mentioned, but these were not found to be themes across multiple studies. The added value of the current review in comparison to the review by Egerton et al is that factors related to interdisciplinary collaboration and the organisational and societal context were in fact identified. Although these domains were relatively small in terms of number of factors, the current review shows that these factors can also influence the implementation of LIs and thus offers an even broader perspective on the implementation status of LIs within OA care. Besides an expansion of the review’s scope (ie, the inclusion of quantitative data and the perspectives of secondary HCPs), this broader perspective of our review most likely arises from the date of the search. The vast majority (72%) of the included articles were in fact published in the past 5 years (after Egerton et al had conducted their review), which shows that there is growing attention for the role of lifestyle as treatment for hip and/or knee OA. Very recently another scoping review has been published, conducted by Nissen et al,63 which focused on clinicians’ beliefs and attitudes about physical activity and exercise therapy as treatment for hip and/or knee OA. The authors thematically analysed qualitative data from four types of HCPs (physiotherapists, general practitioners, orthopaedic surgeons and rheumatologists). Their main finding is that many clinicians perceive OA to be a low priority ‘wear and tear’ disease. In addition, they identified a relative lack of knowledge about and interest in physical activity and exercise management among many clinicians. These findings are also reflected in our results (especially in the domains disease factors and individual HCP factors). In addition, even more barriers and facilitators have been identified in the current review. Compared with this review by Nissen et al, our review again has a broader scope (ie, the inclusion of weight management, quantitative data and the perspectives of more types of HCPs) and can therefore be seen as relevant addition to the existing literature on this topic.
In addition to summarising the existing literature on barriers and facilitators for implementing LIs, this review aimed to identify potential gaps in literature on the participation of HCPs. Although we aimed to include perceptions of various primary and secondary HCPs, the results show that studies to date have mainly focused on the views of physiotherapists and general practitioners. These primary HCPs may well be the first point of contact for patients within the care pathway, yet we recommend that other relevant disciplines—like dieticians, lifestyle counsellors, practice nurses and orthopaedic clinicians—be more involved in follow-up research, allowing for a more complete understanding of the patient journey in OA care. Special attention should then be drawn to potential differences in perceived barriers and facilitators between types of HCPs, so that implementation strategies can be tailored as much as possible to the various types of HCPs and their clinical practice.
The resulting overview of barriers and facilitators can be used to improve the implementation of LIs in daily practice. This overview presents factors that are relevant for individual HCPs, as well as for policy-makers, who can facilitate the organisational and societal context in which primary and secondary HCPs work. When developing implementation strategies, possible interactions between the various domains should also be considered. For instance, more time (domain 5) can be used in various ways by HCPs: for their own education (domain 2), provision of information to patients (domain 3), or interdisciplinary consultation (domain 4). Another example is that societal changes in health insurance or payment structures (domain 7) can lead to increased accessibility of LIs (domain 1), and that limited financial resources might be less of an obstacle for patients (domain 3). Hence changes related to the established factors can have positive effects on multiple levels.
Within the domain of intervention factors, a separate category was created for factors specific to delivering LIs via telehealth. Attention for this modality of healthcare provision has been growing for some time.64 In addition, during the course of the current review the COVID-19 pandemic emerged, which meant that many HCPs actually had to use telehealth in their daily practice.65 Although telehealth was not a specific focus of this review, it could be interesting to further investigate the experiences with telehealth and its value for long-term counselling of patients with hip and/or knee OA on behavioural change.66
To the best of our knowledge, this is the first review to focus specifically on the implementation of LIs as conservative treatment for hip and/or knee OA while taking into account the perceptions of all primary and secondary HCPs involved. Both qualitative and quantitative data were included, providing broad insight into the topic. All included studies were conducted in North America, Europe and Oceania. Given that the majority of these studies were conducted quite recently, our results are expected to be representative of the current situation in these continents.
There are also a few limitations to acknowledge. First, ‘implementing LIs’ was defined very broadly and can be seen as an umbrella term, ranging from mentioning a healthy lifestyle to running specific lifestyle programmes. Due to the heterogeneity of the included studies in terms of study design and evaluated LIs, no distinction was made between the different ways of implementing LIs during data analysis. Consequently, the identified barriers and facilitators may not fit with every single way of implementing LIs, but may rather provide insight into the full spectrum of influencing factors. Although data synthesis has not been performed separately for physical activity and weight management either, the created overview gives us the overall impression that barriers and facilitators related to these two lifestyle components are quite similar. One barrier that seems to be unique to weight management is the perception of it being a difficult or sensitive subject to discuss. Regarding physical activity, the perception that it is unsafe or has negative effects seems to be a unique barrier. Second, although data extraction and quality assessment were performed by two researchers independently, data analysis was performed primarily by one researcher. By discussing the resulting classification of factors and any doubts during the process with members of the research team, we aimed to increase the reliability of our findings. Third, the chosen cut-off percentage for extracting quantitative data was based on other scoping reviews combining the results of quantitative and qualitative studies.24 25 Therefore, there is a chance that factors that would have been extracted when using a lower cut-off percentage are missing. However, it is also possible that these factors were already extracted from the other included studies and therefore still included in our results. Lastly, as we did not search grey literature there is a slight chance that relevant studies may have been missed.
The comprehensive overview of barriers and facilitators for implementing LIs in patients with hip and/or knee OA by HCPs resulting from this review can serve as a basis for further research and the development of implementation strategies that focus on both the individual and the environmental context of HCPs. However, what the relative importance of the identified factors is and whether differences exist between the various types of primary and secondary HCPs with respect to these factors are not known yet. Further research is required to provide more insight into this relative importance and therewith the most relevant targets for change in daily practice.
Conclusion
This review has shown that multiple factors influence whether or not HCPs implement LIs when treating patients with hip and/or knee OA. Data analysis has resulted in a comprehensive overview of influencing factors, where barriers and facilitators have been subdivided into nine domains, both at an individual and at several environmental levels. The review contributes to existing knowledge about the implementation of LIs by identifying multiple factors related to the intervention, interdisciplinary collaboration and the organisational and societal context. The broad inventory created in this review can be a first step towards an improved implementation of LIs by HCPs in OA care. Future research in this area should focus on determining the relative importance of the identified factors involving all relevant disciplines of primary and secondary HCPs.
Data availability statement
Data sharing not applicable as no datasets generated and/or analysed for this study.
Ethics statements
Patient consent for publication
Ethics approval
This study does not involve human participants.
Acknowledgments
The authors would like to thank Truus van Ittersum for her advice on search strategies and Annemarie Jenks for her contribution to the study selection process.
References
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
MS and IvdA-S contributed equally.
Correction notice This article has been corrected since it was first published. Table 2 and 3 has been updated.
Contributors Conception and design: SB, RD, LHVvdW, MS and IvdA-S. Collection and assembly of data: SB and JvB. Analysis and interpretation of the data: SB, MS and IvdA-S. Drafting of the article: SB. Critical revision of the article for important intellectual content: SB, JvB, RD, LHVvdW, MS and IvdA-S. Final approval of the article: SB, JvB, RD, LHVvdW, MS and IvdA-S. Obtaining of funding: SB, RD, LHVvdW, MS and IvdA-S. Guarantor: SB.
Funding This study is supported by a scholarship from the University of Groningen/University Medical Center Groningen (grant/award number: not applicable).
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.