Introduction

Some sections of this report have been reproduced from the study protocol (www.fundingawards.nihr.ac.uk/award/17/17/02). This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) licence, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: https://creativecommons.org/licenses/by/4.0/. The text below includes minor additions and formatting changes to the original text.

Background

Pilonidal disease is a common condition that affects around 26/100,000 of the population – predominantly young, working people.1 The term ‘pilonidal’ derives from the Latin words for hair (pilus) and nest (nidus). It is an acquired disease resulting in obstruction of hair follicles in the natal cleft (the anatomical groove between the buttocks). Subsequent rupture of the follicles leads to abscess and sinus formation. Risk factors for development of the condition include male gender, extensive body hair, young adulthood, family history, local trauma, sedentary lifestyle, poor hygiene, an anatomically deep natal cleft and obesity.1–3 Once established, the condition persists and progresses through insertion of ingrown or loose hairs into the sinuses.2,3 The term pilonidal sinus disease (PSD) encapsulates a wide spectrum of abnormalities ranging from relatively asymptomatic simple sinuses to complex abscess cavities with multiple sinus tracks that persist despite repeated surgical intervention. Individuals present either as an emergency with a painful abscess between the buttocks or electively with a chronic cycle of pain and discharge from the sinuses, causing significant disruption to employment, relationships and quality of life (QoL).4

The ideal management of PSD should be simple, safe, cost-effective, easy to perform and lead to a rapid return to normal activities, with low rates of acute wound complications (including infection, seroma, haematoma), recurrence and rapid wound healing. These aims are not reliably delivered by current surgical practice and there is no consensus on how to manage based on disease characteristics.

Pattern of disease and management options

Patients often present with acute infection and abscess formation. Abscesses usually require hospitalisation with incision and drainage of the abscess cavity. One in five patients present with recurrent symptoms following emergency surgery.5 This picture of relapsing and remitting infections is typical of chronic PSD.

Treatment of chronic PSD is surgical, usually using two essential components: excision and closure. The exceptions are phenol injection and fistuloscope/diathermy as stand-alone treatments (which aim to induce fibrosis and obliterate the tracks) and seton insertion which may induce fibrosis, allowing the possibility of a simpler subsequent surgery. There is no clear consensus as to which approach for each component is superior. For those procedures that involve excision, the tissue removed may be minimal (e.g. curettage or excision of the ‘pit’) or there may be substantial excision of the affected area and surrounding tissue to ensure complete removal of disease. The resultant wound may be left open to heal slowly by secondary intention, or it is closed with glue6–8 or sutures. The skin closure technique may be midline or off-midline. In the off-midline technique, the wound is positioned adjacent to the natal cleft, rather than in the natal cleft itself, in order to theoretically aid healing.8,9 Examples include: the Karydakis flap, Bascom cleft closure (Bascom II), rhomboid and Limberg flaps.

Monetary and humanistic burden

Pilonidal disease is relatively common and represents a significant burden to primary and secondary care in the NHS. The 2012 hospital episode statistics (HES) data reported 13,239 hospital admissions for PSD.10 At present, both emergency and the most common elective excisional surgical treatments leave large open wounds that may take months to heal.6,7 Patients consequently require prolonged wound care from community healthcare services. As the disease tends to affect young otherwise healthy adults, this prolonged need for dressings and general wound care impacts on education, work, intimacy and social life, pain, recurrent infection and fear of wound deterioration, all severely affecting QoL.11,12 Alternative techniques including minimally invasive interventions that aim to close the wound away from the midline may reduce the burden to the patient, but their efficacy outside the care of dedicated enthusiasts is not clear.

Current evidence base

The optimum treatment that is both easy to perform and results in rapid healing and minimal complications is not clear. This is reflected in varied practice throughout the UK with a perceived random selection of the procedure techniques detailed above. Some of these procedures result in lengthy healing times and long periods of incapacity. The literature on PSD is large but mainly consists of single-centre cohort studies looking at individually favoured techniques. Many of these have reported very low recurrence and infection rates for almost all procedures.13 It has proven difficult to replicate these results in ‘real life’. In addition to the literature being mainly from single-centre cohorts, most studies make no attempt to stratify patients or detail the extent of disease or the adjuvant management (antibiotics, anaesthetic, postoperative care). There have been numerous randomised controlled trials (RCTs), and nearly 40 systematic reviews that focus on management – including two Cochrane Reviews. Most of these systematic reviews include meta-analyses of cohort studies only or analyse comparative RCTs and non-RCTs (often combining these data) for numerous interventions with varied controls. The methodological flaws of many individual studies and systematic reviews, coupled with the uncertainty of front-running interventions and an absence of a universally accepted control, make the value and interpretation of the data difficult.14

The first Cochrane Review demonstrated that healing through secondary intention had lower overall recurrence rates compared to primary closure but at the expense of longer healing times.14 Another systematic review reached the same conclusion but also compared two types of closure, suggesting off-midline to be preferable to midline.15 The authors also concluded that outcome measures, such as time to healing, were poorly analysed, and health economic data were lacking. They proposed that future trials should be adequately powered, multicentric and include valid methods of assessing surgical outcomes. A systematic review of wound care after excision found no best practice guidelines and only one clinical pathway.16

The second Cochrane Review focused on fibrin glue (FG) in the treatment of PSD.17 The authors concluded this was a promising and appealing option as monotherapy given the non-invasive nature and that it could be performed as a day-case procedure, under local anaesthesia. These conclusions echo the conclusions of a previous meta-analysis, both suggesting a need for further research.18 Nevertheless, the research to date has largely considered FG as an adjunct to surgery and although small, single-centre observational studies6,7,19–21 have been published, there is no RCT of FG as monotherapy in treatment of PSD.

Rationale

Currently, there is a lack of evidence regarding classification of disease, what are the front-running interventions, whether there is clinical equipoise for these interventions and whether comparative studies for these interventions are feasible in terms of recruitment, and finally what outcome measures are relevant to patients, can be easily and reliably measured and are sufficiently sensitive to change. Given the efficacy uncertainty surrounding a multitude of operative techniques, compounded by the reported negative implications for recovery, there is a need to improve the evidence base to guide future pilonidal management.14

Research objectives

The aim of the PITSTOP study is to answer the following research questions:

1. What are the different subtypes of pilonidal disease for which the various treatment options are indicated?
2. What combinations of excision and closure techniques are used?
3. Which outcomes do patients value and which interventions do they prefer?
4. What further research is needed?

To answer the research questions posed, we aimed to complete the following:

1. Conduct a survey of clinicians to assess management preferences.
2. Follow patients with symptomatic pilonidal sinus referred to each collaborating site, prospectively record details of their pit/track anatomy, surgical management, medical events and health-related QoL until 6 months after their operation.
3. Describe the combination of interventions currently in use and quantify clinical and patient-reported outcomes (PROs) associated with each.
4. Identify patient-specific disease features that might predict poor outcome in each treatment group by risk-modelling methods.
5. Derive a case mix-adjusted estimate of the risks associated with common treatment options, using causal inference methods to provisionally rank the optimal management strategies among patients for whom more than one treatment is considered appropriate.
6. Provide an overview of patient views and experiences.
7. Collect the views of patients on which interventions they would rather avoid and which outcomes they most value.
8. Validate a classification system.
9. Reach a surgeon-based consensus on which subtypes of pilonidal disease may benefit from which treatment options.
10. Reach a surgeon and patient-based consensus on research priorities.