This protocol article is generated following the PRISMA-P guidelines. A completed copy of the PRISMA-P checklist is provided (Additional file 1).
A systematic literature search will be conducted in EMBASE.com, PubMed.com, Scopus and Web of Science bibliographic databases from their inception to January 17th 2020, alongside a search for published studies and Epubs ahead of print in journals with relevance to spine surgery, such as Spine, The Spine, EuroSpine, Global Spine, the Spine Journal, International Orthopedics and Journal of Bone and Joint.
Furthermore, reference-lists and citations of included studies will be searched in order to identify other relevant papers. Finally, a cohort of non-published data from DaneSpine will be included in the review.
The search will be conducted using index-words related to the coccyx and coccydynia. Examples of such are attached (Additional file 2). An experienced librarian, affiliated to the Faculty of Health at Aarhus University, will be consulted for guidance in designing the search.
Articles will be screened using both EndNote- and Covidence software for duplicates, following a screening using Covidence software including or excluding articles according to the inclusion- and exclusion criteria. The inclusion and exclusion criteria are created according to the eligibility criteria (Additional file 3).
Studies to be included are any original, peer reviewed randomized control trial, cohort study or case-series, both retrospective and prospective, containing more than five patients with coccydynia. Reviews, meta-analyses, opinions and commentaries are excluded, as well as studies involving less than six patients with coccydynia, which will be classified and excluded as case reports.
Interventions of interest, as noted in the eligibility criteria, are those of any conservative, interventional or surgical nature described in any eligible article. The interventions of interest are not further specified, due to the risk of excluding novel treatments not widely investigated. Papers excluded as case reports will be noted and commented in the discussion section if these concern an intervention of a newer date, not otherwise addressed in the articles included for data analysis.
The inclusion criteria are:
- Publications of original peer reviewed randomized control trials, cohort studies or case-series, available in full text.
- Papers in English, Danish, Norwegian, Swedish, Serbian, Croatian, Bosnian and Spanish language.
- Studies addressing treatment of patients with coccydynia with any available treatment option.
The exclusion criteria are:
- Animal studies and studies addressing evaluation of technical equipment.
- Studies including patients of less than 16 years of age.
- Studies without treatment outcome (e.g. studies of etiology).
- Acute coccydynia or patients with coccydynia reported with a duration less than two months.
- Studies solely concerning secondary coccydynia as a complication to another condition (mimics of coccydynia, e.g. cancer-derived pain and infectious-derived pain).
- Systematic reviews, meta-analyses, opinions, commentaries and studies involving less than six cases.
Secondary coccydynia also includes pain derived from previous surgery in the ano-rectal area. This includes prior coccygectomy, surgery for pilonidal cysts, ano-rectal surgery, as well as any other surgical intervention in the area. This is due to the risk of developing granulation tissue, adhesions, chronic inflammation and possibly a change in elasticity of the tissue surrounding the os coccygis, which, over the course of time, can lead to secondary coccydynia.
The screening will be done by two authors independently, involving a third author in case of disagreement. Addressing possible inclusion bias, a pilot test of 50 articles will be conducted. Articles will primarily be excluded based on title and abstract only, followed by a full text screening. In cases where initial screening cannot be performed due to the abstract not being available, the full text article will be obtained. In order to do full text screening, a thorough search for available full texts will be conducted, should an article not already be accessible through the reference managing tool.
To assess article quality and bias, two authors will independently evaluate all eligible articles, followed by an attainment of consensus, using Covidence software. Data extraction will likewise be performed using Covidence, independently in duplicate, and compared when completed.
The included articles will be divided into groups based on treatment strategy, in order to perform meta-analysis. The meta-analysis will be performed using STATA software, in each separate group, if the amount of studies included for each treatment strategy is adequate. In case of inadequate data for meta-analysis, or if data is not suited for meta-analysis, a qualitative estimation will be made, by summarizing the study findings. In the case of several eligible studies on a given treatment option, a study will be included in data synthesis corresponding to the applicability of its reported outcome measure.
The primary outcome measure for comparing and evaluating the efficacy of the different treatment options are validated pain-scores, e.g. VAS-score. Secondary outcome measures are measures of disability, e.g. Oswestry Disability Index (ODI), quality of life, e.g. EuroQol-5-Domain (EQ-5D), work absenteeism, complications to the treatment and patient reported effect of treatment.
If any relevant data is missing, the respective authors of the study will be contacted, concerning assessment of the data. If data is inaccessible or insufficient, an estimate will be conducted.